SECTION VII

DISEASE IN CAPTIVE WILD MAMMALS AND BIRDS

INCIDENCE, DESCRIPTION, COMPARISON

BY

HERBERT FOX, M.D.

PATHOLOGIST TO THE ZOOLOGICAL SOCIETY OF PHILADELPHIA, DIRECTOR OF THE

WILLIAM PEPPER CLINICAL LABORATORY, UNIVERSITY OF PENNSYLVANIA

WITH A FOREWORD BY

CHARLES B. PENROSE, M.D.

PRESIDENT OF THE ZOOLOGICAL SOCIETY OF PHILADELPHIA

[Illustration: ZOOLOGICAL SOCIETY OF PHILADELPHIA. INCORPORATED 1859]

PHILADELPHIA, LONDON & CHICAGO

J. B. LIPPINCOTT COMPANY

COPYRIGHT, 1923, BY HERBERT FOX

THIS BOOK

IS DEDICATED TO

CHARLES BINGHAM PENROSE, M.D., PH.D., LL.D.

IN GRATEFUL APPRECIATION OF HIS FRIENDSHIP

AND OF HIS GUIDANCE AND ENCOURAGEMENT

IN ALL MATTERS PERTAINING

TO THIS LABORATORY.

CONTENTS

PAGE

FOREWORD—DR. CHARLES B. PENROSE 1

SECTION

I. INTRODUCTION 17

Zoological Classification

Numerical List of Autopsies Upon Which the Work is

Based.

II. DISEASES OF THE HEART 48

III. DISEASES OF THE BLOOD VESSELS 66

IV. DISEASES OF THE BLOOD AND BONE MARROW 83

V. DISEASES OF THE LYMPHATIC TISSUES INCLUDING SPLEEN 114

VI. DISEASES OF THE RESPIRATORY TRACT 134

VII. DISEASES OF THE ALIMENTARY TRACT

The Tube Proper 166

The Liver 222

The Pancreas 244

The Peritoneum 260

VIII. DISEASES OF THE URINARY TRACT 263

The Kidney

IX. DISEASES OF THE FEMALE REPRODUCTIVE ORGANS 287

X. DISEASES OF THE MALE REPRODUCTIVE ORGANS 313

XI. DISEASES OF THE DUCTLESS GLANDS.

The Thyroid 316

The Thymus 336

The Suprarenal 336

XII. DISEASES OF THE SKELETON AND ITS JOINTS 343

XIII. DISEASES OF THE CENTRAL NERVOUS SYSTEM AND SPECIAL SENSES 372

The Eye 402

XIV. CONSTITUTIONAL DISEASES 410

XV. THE RELATION OF DIET TO DISEASE BY E. P. CORSON-WHITE,

M.D. 415

XVI. NEOPLASMS 462

XVII. THE INFECTIOUS DISEASES.

Tuberculosis 483

Mycosis 558

Streptothricosis 567

Miscellaneous Infections 596

XVIII. ANIMAL PARASITES, THEIR INCIDENCE AND SIGNIFICANCE, BY F.

D. WEIDMAN, M.D. 614

LIST OF TABLES

PAGE

1. The incidence of degenerative and inflammatory changes in the

heart 51

2. The incidence of hypertrophy and dilatation of the heart with

principal associated lesions 57

3. A condensation of the important features of Tables 1 and 2 63

4. The heart-to-body-weight ratios 63

5. The incidence of arteriosclerosis 71

6. The differential percentage of the circulating leucocytes in a

number of different animals 84

7. The various types of splenitis 126

8. The incidence of the various types of bronchitis and of

pulmonary parasites 142

9. The incidence of the various forms of pneumonia 150

10. An analysis of cases of abscess and gangrene of the lung 156

11. The incidence of gastroenterocolitis, its distribution and an

analysis of the causes 182

12. An analysis of the inflammations of the alimentary tract in

Ungulata 196

13. An analysis of the inflammations of the alimentary tract in

Marsupialia 200

14. An analysis of the cases of pancreatitis, the associated

pathology and the details of the anatomy of various orders 252

15. The weight of the thyroid body in relation to body weight 318

16. The incidence of the various enlargements of the thyroid body 326

17. The incidence of cases of degenerative bone disease in the

various orders 357

18. The weight of the brain and the relation of this to the body

weights in 196 animals 388

19. An analysis of pathological conditions in terms of diet 423

20. An analysis of the diets used in the Philadelphia Garden 426

21. The incidence of tumors 464

22. An analysis of the breeding, captivity and visceral

distribution of neoplasms, of tumor-bearing animals 466

23. An analysis of the incidence, character and distribution of

tuberculosis 486

24. The incidence of parasites in the zoological orders 630

25. The incidence of heterakis in pheasants 635

26. The incidence of various parasitic orders and families 636

27. The visceral distribution of parasites 639

28. The occurrence of blood parasites in zoological classes 651

FOREWORD

BY

CHARLES B. PENROSE

The work on which this book is based was begun in November, 1901. From

that date, systematic autopsies were made on animals dying in the

Philadelphia Zoological Garden. Previously autopsies had been made very

rarely and only on animals of especial importance and interest.

Pathological conditions were occasionally noted in animals subjected to

anatomical study. The work was strictly volunteer, for there was no one

on whom the Society had the right to call. Dr. Henry C. Chapman, a

former Director, whose interest was in physiology and comparative

anatomy, made nearly all the autopsies that were made before the

beginning of the present work. In the annual reports from the foundation

of the Garden in 1872, very few such examinations are recorded. In some

reports there are lists of important deaths, but no record of the cause

of death.

This state of things was not peculiar to the Philadelphia Garden. It

existed in every zoological garden in the world. It exists in most of

them to-day. When an animal died it had no interest or value except for

its hide and bones. Rare specimens were sent to the Academy of Natural

Sciences from the Philadelphia Garden. The great majority, however, were

immediately destroyed, and thus during the twenty-nine years from the

foundation of the Garden, preceding this work, there have been lost many

opportunities—some of which will never recur—of increasing our knowledge

of pathology.

This book gives results of the study of animals that have not been

subjected to experimental procedures and conditions, and though their

mode of life has not been that strictly natural to them, yet they have

not been influenced by any of the artificial procedures of the

laboratory which are usually followed in investigations on animals.

Though the object of the work was the pursuit of knowledge for its own

sake, yet results of practical value have followed: hygiene has been

improved; disinfection has been made scientific; epidemics have been

arrested; some diseases, notably tuberculosis in monkeys, and

spiropteriasis in parrots, have been practically eliminated.

The value of the work is recognized by the keepers. Their interest has

increased and their morale has improved. The frequent deaths in a large

collection of animals are discouraging, and a good animal man must have

courage and optimism—traits that are stimulated by the knowledge that

every animal that dies is studied to determine the cause of death, and

to prevent its recurrence.

Some results of this study are to be considered as “raw material,” while

others permit cautious or tentative conclusions. The first include—

visceral weights, incidence of certain lesions like anemia and hepatic

cirrhoses, occurrence of calculi and observations on weak hind quarters,

convulsions and constitutional diseases. The second include—eradication

of tuberculosis and spiropteriasis, the response of the mammalian and

avian heart to strain and disease viruses, the origin of pneumonia in

birds, the genesis of bronchiectasis, the nature of osseous degeneration

with relation to diet and alimentary tract, the comparative anatomy,

physiology and pathology of the female genitalia, the occurrence of

lesions in the thyroid comparable to those in man, the character of

kangaroo disease.

Great praise is due Dr. Herbert Fox and his assistants Drs. F. D.

Weidman and E. P. Corson-White, for the splendid scientific spirit and

thoroughness with which they have done this work, with no adequate

remuneration, except the intangible reward appreciated only by the real

research worker.

It is a mistake to think that all animals in the wild state are healthy.

The healthy wild animals that we see are the survivors, the sick and the

weaklings having died. Undoubtedly diseases are fewer than in captive

animals; but on the other hand wild animals are exposed to dangers to

which captive animals are not exposed—such as lack of care in sickness

and old age, starvation, and attacks of enemies that feed on them. The

maximum longevities in some species are probably in captive animals. It

is doubtful if a wild animal ever reaches the greatest age possible to

it.

Many kinds of parasites have been found in wild animals captured only a

short time before arriving at the Garden, so that they must have existed

in the wild. Thirteen wild cats received from South Carolina within a

few days after capture were infested with intestinal, muscular, and

pulmonary parasites. Several years ago there were received from the

Island of Chincoteague, off the coast of Virginia, a number of native

birds recently captured, all of which had mould disease of the air sacs.

This happened on several occasions, so that it became necessary to

reject all birds from this locality. Among the birds were meadow larks

and cardinals.

Hunters not infrequently kill animals with disease, and if more hunters

knew enough to recognize the disease there would be more recorded cases.

Sick animals are not as likely to be killed by the hunter as healthy

ones, as sick animals seek seclusion and do not move about. In many

localities of the United States white-tailed deer are infested with the

liver-fluke. Trout and other fish in remote mountain streams are found

with tapeworms. Round worms and other parasites infest the white

rhinoceros in the African forest.

In many instances the parasites and the host, when in health, get on

very well together; but when the host weakens the parasites may give him

the finishing stroke.

Though some morbid conditions described in this book are peculiar to

captivity, yet it seems reasonable to assume that many of the diseases

found in captive animals occur also in the wild. Some of the extinct

races of animals may have been wiped out by disease.

Captivity causes numerous physical and mental disarrangements.

Unaccustomed, unnatural and unvaried food, change of climate and

environment, physical and mental degeneration from disuse of muscle and

brain, fear, ennui, nostalgia, lack of the exhilaration of chasing and

being chased, unsatisfied sexual feeling—all react harmfully on the

captive.

No captive animals get their natural food; and though some, like the

carnivora, may get approximately their natural food, yet they do not get

it in the natural way. They have but little variety and may miss

elements important to their well-being. They get only certain cuts—

muscle and bone; they do not get blood, guts and glands. The lion’s meat

is handed to him. He does not tear down his prey; and one result is that

the jaws of the captive-bred lion differ decidedly in shape from the

jaws of the wild-bred lion. He gets his food regularly, with awful

monotony—twelve pounds of meat at 3.30 p.m. day after day; there is no

alternation of feasts and fasts, with consequent change in the balance

of the body reserves.

Some animals, such as caribou, the moose, the black cock, the hoatzin,

the koala, do not long survive captivity, because it is impracticable to

obtain their natural food. Gastrointestinal disease is the commonest

disease of wild animals. Twenty-five per cent. of sick humans in

civilized communities also suffer from it. On the other hand, many

animals become accustomed to the new diet and thrive on it.

Animals also often thrive in a climate very different from that of their

natural habitat. Some animals from warm countries, though kept outside

without any artificial heat, get on very well during the severe weather

of Philadelphia winters, when the temperature often drops to zero

Fahrenheit. For the past two years it has been the custom to put

outdoors all monkeys—of value—that are suspected of having tuberculosis.

The cheap monkeys are killed. The outdoor monkeys are kept in fair sized

cages—five feet square and six feet high—usually singly, though

sometimes two are together. The vervet, the grivet, the leonine macaque,

the yellow baboon, the Hainan gibbon and many others, have not only

survived the climatic conditions but have not succumbed to tuberculosis.

South American monkeys do not stand cold as well as Old World monkeys,

and cannot be kept out in severe winter weather.

The monkeys that are kept indoors during winter have free access to the

outside through swinging doors and they often go out voluntarily in the

coldest weather. The same is true of other animals. A note made several

years ago (February 12, 1914) states: “Temperature last night was 1° F.

At 2 P.M. outside temperature 13° F., in carnivora house 25° F.,

elephant house 38° F., giraffe house 39° F., monkey house 42° F. Two

Bengal tigers were voluntarily outside. Monkeys that have been out all

winter are: two Barbary apes, Hainan gibbon, lion-tailed macaque, yellow

baboon, grivet monkey, pigtailed macaque, and eleven rhesus macaques.

All the animals appeared comfortable.”

The physical condition of the animal and the kind of cold—damp or dry—

have much to do with its ability to stand low temperatures. Monkeys have

passed through very severe winters without damage, and subsequently in a

less severe winter have had frozen fingers, toes or tail.

The size of the cage or pen has not as much effect upon the well-being

of the animal as might be expected. Reptiles, birds and mammals do as

well in cages and pens of medium size as in very large ones. A deer or

antelope in a large enclosure does not use all its domain. It usually

has a favorite corner near the food, water and shelter, and stays there.

Nor has a large enclosure been found perceptibly to diminish mortality

from cage-mates. The stronger will follow the weaker until he gets him,

no matter what the enclosure. Even in the large flying cage for birds it

is necessary to keep out those of a scrappy disposition. From the point

of view of the public small enclosures are more satisfactory.

Mental disease in captive animals offers a fascinating field for study—

now chiefly speculative. Many conditions are present to produce it—all

the conditions that cause prison psychoses in man. And many if not all

the insane and perverted acts of animals have their counterpart in the

human. Masturbation is very common in mammals. Eating of their own

feces, coprophagy, is not infrequent, and is especially notable in one

of the highest types—the Chimpanzee. Perhaps occasionally coprophagy may

be due to some defect in diet. There is no instinctive disgust at

excrement in the lower animals any more than there is in the uneducated

child. Nevertheless, eating feces cannot be healthful, and probably does

not occur in nature; and occurs only in the human with mental disease.

Some of the insane acts of animals if prevalent in the wild would

probably cause the extinction of the race. Such are killing of the young

by the father and by the mother; killing of the female by the male,

usually during rutting time, in some instances reminding one of Sadism

in man. This kind of sexual killing does not often occur in the wild.

The female has a better chance to escape, and the male probably does not

feel so inclined to damage her when he chooses her himself as when she

is chosen for him by his gaoler. When the mother devours her young it is

usually shortly after birth. I have, however, the record of a Jungle cat

(_Felis chaus_) who ate two of her kittens when they were seven weeks

old. Some of the domestic animals devour their young; the sow often does

it, and occasionally the bitch.

Sucking, gnawing and eating parts of itself or of a cage-mate is not

uncommon in a variety of animals. Bears lick their paws until they are

sore; a monkey may gradually gnaw away its tail from the tip to the

body; an ocelot (_Felis chibigonazon_) bit open his scrotum and devoured

his testicle; a Tasmanian devil (_Sarcophilus ursinus_) bit off one of

his front feet at the wrist; a monkey may gradually gnaw away its

fingers; and numerous other self-inflicted mutilations occur. Often

there is a local irritating cause, as skin disease, lice, or freezing.

But in many cases no local cause can be found, as no local cause can be

found for thumb-sucking or nail-biting in the human.

The surgery done by monkeys on their frozen fingers and toes is

interesting. After the flesh has sloughed the monkey bites off the

protruding phalanges, apparently without pain, so that satisfactory

well-covered stumps are made.

Animals often mutilate their cage-mates in an amicable way as

distinguished from fighting. A bear may lick its mate’s ears until the

hair and skin are gone. A monkey may eat its mate’s tail or patches of

its skin, the victim lying placidly while the process goes on. Many

animals are addicted to perverted acts on their own or their mate’s

sexual organs.

It is probable that the phenomena just mentioned are due to confinement,

idleness and ennui, and that they do not often happen in nature where an

animal is kept busy seeking his food, fighting and avoiding his enemies,

attending to his mate or mates, and meeting the various vicissitudes of

his environment.

It should be remembered, however, that the members of a wild species

vary in intelligence and temperament, as humans do. There are morons and

perverts among animals in the wild; but not being coddled by the normal

members of the species, they have a poorer chance than has the subnormal

human of surviving and of transmitting their peculiarities.

Fear, ennui, loneliness and nostalgia, by affecting the minds of captive

animals, react on their physical condition. Some animals have the fear

of man bred in them. The young often show it from time of birth. This is

especially common in animals that have survived for generations in

proximity to man. It is one reason for their survival. The mother and

father may have become tame and gentle in captivity and yet the young

one may be a wild thing from birth. Such fear is sometimes

uncontrollable, an apparently slight cause making the animal dash itself

against the fence of the enclosure. It is not mere speculation to

discuss the physical effects of the emotions on the animal body. It has

been shown that fear, anger, and grief bring about distinct measurable

physical changes. Dr. Corson-White has found that the red corpuscles are

increased by over two million per cubic centimetre in the blood of a cat

frightened by a dog barking at it. The amount of blood sugar is also

increased.

Such observations are suggestive in a consideration of the changes that

may occur in a captive animal subjected to acute and chronic fear.

The monotony of a captive animal’s life is broken only by feeding, the

sight and sounds of others in the same building or nearby, and by

visitors. Many animals show their appreciation and pleasure when

visitors approach, and some of the more intelligent animals, bears and

monkeys and some birds, “show off” apparently to keep the visitors

there. When there is nothing doing, some stand swaying their heads, like

a weaving horse, or pacing the cage, inanely tagging at each turn the

side of the cage with the head or other part of the body—often so

persistently that a sore is produced. Nearly all animals are social and

suffer from loneliness when kept by themselves. This is true even of the

lowly forms. The keeper of the reptile house reported that a giant

tortoise became despondent and refused to eat when his companion, a

leopard tortoise, was taken from him, and that he braced up as soon as

the leopard tortoise was returned. It is not necessary that the

companion be of the same species, or even of the same family. A lion or

a tiger may be satisfied with a little dog for a companion, and there

was an African rhinoceros at the Philadelphia Garden that was very

discontented and unhappy when alone and became perfectly satisfied when

she was given a domestic goat as a cage-mate; and the huge rhinoceros

stood for a good deal of butting and bullying from the goat without

retaliating. A sympathetic keeper may do much to relieve the loneliness

of the animals in his care.

Nostalgia, or homesickness, has been felt by all men. Some have died of

it. The tradition among writers is that it affects young people and

those who have been living nearest to a state of nature. In this country

the American Indian and the negro are affected more than the whites.

Much was written of it after the Franco-Prussian War and the American

Civil War. It is a real condition, capable in extreme cases of causing

death and of so weakening the sufferer as to make him more susceptible

to the invasion of other diseases. At the present day we hear less of it

among civilized people than formerly, perhaps because the conception of

home has been broadened by modern methods of intercommunication. The

wild animal’s conception of home is narrow; he comes directly from it

into an environment where he may see many other animals, but not one of

his own kind. Predisposing causes of nostalgia are stronger with him

than with the human. That home means a great deal to animals is shown by

the migration of birds—the return of the carrier pigeon, and of the lost

dog, and of the swallow, which returns every year to the same nesting

place.

All animals long for the things of nature—open air, earth, grass and

water. They are thrilled when their feet touch the sod. Even the

hippopotamus gambols when he leaves his concrete house and his feet

touch earth and grass.

The face and carriage of many animals cannot express feelings as in the

human, though it is not unreasonable to assume that animals may indicate

feelings by expression understood by their mates, though not understood

or even noticed by man. When they can express it in a human way their

feelings may be read. The dejection of nostalgia is especially shown by

anthropoid apes. Gorillas have been noted for it from the earliest

writers. The orang is prone to it, shows it by his attitude and

expression, and sometimes dies of it.

It is stated in _A Handbook of the Management of Animals in Captivity in

Lower Bengal_, p. 130, that elephants have been observed to shed tears

abundantly if forced to leave their old home and surroundings. How much

other animals who cannot express homesickness may feel it, and how often

it is a cause of unhappiness, depression and predisposition to disease,

it is impossible to say.

Most wild animals in captivity are sterile. The reason is not known. It

shows the profound effect of captivity. It would be difficult to

determine whether the sterility of a mating is the fault of the male or

the female.

There is no apparent rule for sterility. Some families are always

sterile in captivity, others are fertile, even with very unfavorable

surroundings. The deer, horses, hippopotamuses, pigs, goats, sheep and

oxen, are good breeders; while antelopes, rhinoceroses, giraffes,

elephants, are poor breeders. Some members of a family may be good,

others poor. The lion and puma breed fairly well; the tiger, leopard and

jaguar, very poorly. Bears breed well, but the mother usually destroys

her young.

We cannot mate wild animals and birds simply by putting males and

females together in the same cage. Domestic mammals and birds usually

mate under such conditions, but wild ones often refuse. Many mammals and

probably all birds that are not polyandrous or polygamous reserve the

right to select their mates, and if the sexes are put together by man

they may view each other with indifference or with animosity. There are

many males and females of the same species of mammals at the Zoological

Garden that will not consent to live together. A male monkey in a cage

with several females will very often select one female for his mate and

will have nothing to do with the others.

Among monkeys fertility varies greatly. It is not practical to determine

the ratio among the various kinds, as some kinds are much commoner in

zoological collections than others. I think that in general the Old

World monkeys (_Cercopithecidæ_) are better breeders in captivity than

those of the New World (_Cebidæ_). The anthropoid apes are very poor

breeders indeed; of the many gibbons, orangs, and chimpanzees, that for

years have been captive in Europe and America, it is probable that only

the chimpanzee has bred, and that very rarely.

Refusal to mate, sterility, infanticide by father and mother, and sexual

killing keep down reproduction in zoological gardens; and the number of

young ones is a good indication of the character of a garden and of the

provisions made for the happiness, comfort and health of the animals.

With the birds in a zoological garden the conditions for nesting and

laying are not good. Caged birds have no material for a nest, no privacy

and rarely lay an egg. The outdoor water birds and the outdoor upland

birds with natural surroundings, with secluded retreats, lay and hatch

very well. Birds like mammals apparently are indifferent to publicity

when copulating, but seek seclusion for laying and nesting—from maternal

fear for the safety of the young.

The sexual instinct in indoor caged birds in a zoological garden is

dormant. Very few copulate and very few lay eggs; pigeons and Mexican

conures (_Conurus holochlorus_) are exceptions to this general rule.

Probably because the sexual instinct is dormant the males never fight

over the females among perching birds, and very rarely kill each other.

In some species of finches, however, as the chestnut-eared (_gn.

Amadina_), the females fight among themselves if there are not enough

males.

Ovoviviparous reptiles breed more often in captivity than one would

expect; and egg-laying snakes often lay eggs, which of course are only

hatched artificially.

Birds suffer less than mammals from the psychological effect of

captivity. The mental development of a bird is much lower. With few

exceptions, like the ruffed grouse, the bird accepts captivity easily

and becomes tame, though he will not stand being touched. He views his

keeper and visitors with indifference or friendliness. If a bird house

is bright, cheerful and sunny, all the inmates thrive and appear to be

happy. These conditions undoubtedly affect the health of the bird, as is

evidenced by their plumage; bright colors that are lost in a dark and

gloomy house are retained and developed when the house is cheerful and

sunny. There are some birds, however, that never retain their colors in

the captivity of a zoological garden. Among them are the scarlet ibis,

the American flamingo, and the roseate spoonbill. It has been suggested

that the loss of color is due to the lack of something in the diet,

mineral or organic, that the bird gets in its natural habitat. Tame

scarlet ibises living with the chickens about the dwellings of natives

in Venezuela retain their brilliant color. The material of the beautiful

red color on the under surface of the wings of the touracou contains

copper, yet these birds retain this color very well in captivity, even

after several moultings.

The source of the copper has long been uncertain. In nature the birds

are fruiteaters, and their diet in captivity consists of bone meal,

zweibach, corn meal, white potatoes, eggs and carrots—foods that are

usually assumed to contain no copper; and no copper utensils are used in

the preparation of the food. Dr. John Marshall, however, writes me that

all the common cereals contain minute quantities of copper; and Dr. Leon

A. Ryan, _University of Pennsylvania Medical Bulletin_, June, 1907,

states that copper may be found in animal tissues. Dr. E. P. Corson-

White has found traces of copper in the bone meal used at the

Philadelphia Zoological Garden. The copper in the red color of the

touracou’s wing therefore comes from the food.

It is probable that a bright and cheerful bird house does not influence

the color of birds by the direct action of light on the color as much as

indirectly by improving the health and spirits of the birds. Coloration

in birds is a very complicated proposition. It depends upon age, sex,

season, health, light, heat, moisture, mode of life, and food. No one

bird house can combine all the conditions necessary for the retention of

natural colors in every species. The desert species from a habitat of

intense light and dryness require for their color a different

environment from the forest species, from a habitat of shade and

moisture. The suppression of sexual feeling in captive birds may

influence color. In nature the finest colors are attained by mating

birds.

It may be said that all animals—except those of nocturnal habit—have a

feeling of joy and well-being in fine weather and bright surroundings

that reacts favorably on the general health.

The variability of the breeding period induced by captivity in many

animals may be mentioned with sterility. It was shown some years ago in

the Philadelphia Garden by the European brown bear which in one year

gave birth on January 16th, and in the following year on July 25th. It

is another evidence of the profound effect of captivity on the captive

animal. I know of no observations of the effect of captivity on the

period of gestation.

There is considerable mortality among captive animals from killing of

cage-mates. I do not refer to sexual killing, already mentioned, or to

fights over a female. Often males, with no females near, cannot be kept

together; probably sexual jealousy is at the bottom of it. Antelope and

deer are especially inclined to scrap. Even a large enclosure will not

save the weaker male; the stronger follows him with horrible

persistency, sometimes for days, around and around the enclosure, often

at a walk, but always on the offensive, at least during the day; until,

careless from weariness, the weaker is caught unawares and finished by a

horn-thrust in the side.

Both birds and mammals often kill their mates when the mate is sick, or

“down” from injury or disease. All animals hate sickness and death, and

show their dislike by attacking or shunning it. Birds may get on happily

together for months until one becomes sick, and as he crouches in a

corner with ruffled feathers the others pick on him and finish him. The

same is true of mammals, the sick one being horned or tramped to death

by the mate with whom he had formerly been on most friendly terms. The

keeper often reports an animal “killed by its mate,” whereas the mate

has only given the _coup de grace_.

This brutality is not universal. Rarely a parrakeet will stand guard

over his sick and dying mate; and we have seen a ratel—of a ferocious

family—stand guard over and resist the removal of his sick companion.

The diagnosis of disease in wild animals is unsatisfactory; usually

impossible; clinical study as we know it in the human is impossible. We

know that the animal is sick, but not why. A certain group of symptoms

accompanies all diseases—dull, rough coat or feathers, refusal to eat,

weakness in the hind quarters, and finally getting down. They rarely

show symptoms of pain—or at least we cannot read the symptoms. The pain

of acute pancreatitis in man is violent, yet many animals die with it

and we cannot tell that they suffer. Animals do not suffer as much as

the human, and they stand the ravages of disease better than the human.

At autopsy we often wonder how the animal could have lived with the

conditions that are found. A monkey may be apparently well until a few

days before his death, though his lungs and abdominal organs may be a

mass of tubercle. A small red howler monkey (_Alonata seniculus_) was in

apparent good health, playful and lively until twenty-four hours before

his death from acute pancreatitis, though his stomach and intestines

contained fifty-one nematode worms, some of which were eight inches in

length.

As diagnosis is unsatisfactory, so is treatment. Usually all we can do

is to treat symptoms; and by the time disease has advanced to the point

of becoming externally noticeable, it has usually gone beyond the reach

of medical treatment. It must also be remembered that drugs vary very

much in their action in different families of animals. Nux vomica will

not kill the gallinaceous birds of North America, and Tenant says that

in Ceylon the hornbill feeds on the fruit of strychnos nux vomica. The

pigeon is immune to opium. The _Felidæ_ are said to be unusually

susceptible to carbolic acid; veratrum viride is harmless to sheep and

elk, but poisonous to the horse; dogs can take with impunity large

quantities of cyanide of potassium. These statements are true when the

drugs are administered by mouth—the usual way of giving them to wild

animals. The action may be different if the drugs are administered

intravenously or subcutaneously. Variations in effect when they are

administered by mouth are often due to chemical variations in the

digestive secretions. It is probable that the action of cyanide of

potash on dogs depends on the amount of hydrochloric acid in the

digestive tract.

When worms or their eggs are found in the stools vermifuges are used,

and with some animals especially liable to infestation by intestinal

worms, periodic doses of vermifuges are given as a prophylactic.

Turpentine is given to the zebra at fixed intervals for the round worm;

santonin, male fern and areca nut to the carnivora for the various worms

that are so common in the intestinal tracts of these animals.

The work of the Laboratory of Pathology is throwing light on the subject

of diagnosis, and though from the character of the clinical material

diagnosis can never be as satisfactory as in the human, yet we may

fairly hope for improvement. Prophylaxis is our chief reliance, and

always will be.

DISEASE IN CAPTIVE WILD

MAMMALS AND BIRDS

SECTION I

INTRODUCTION

“We have also parks and enclosures of all sorts, of beasts and birds;

which we use not only for view and rareness, but likewise for

dissections and trials, that thereby we may take light what may be

wrought upon the body of man.”

The purpose of a menagerie under the auspices of a zoological society

can scarcely be put into better words than those found in this quotation

from Sir Francis Bacon’s _New Atlantis_. Apt as this description of the

mythical island’s collection may be, it is but a reflection of the

teachings of Plato’s original legend of a perfected community, and the

practical applications of these teachings by Aristotle in his _Anatomy

and Physiology of Animals_. The history of human study shows a constant

investigation of lower forms of life, ever broadening in its scope, ever

more satisfying in its explanation of biologic problems and ever

increasing in value from an economic standpoint.

If, however, all animals are to be subjected to “dissections and trials”

there inevitably will come under observation many specimens presenting

variations from the accepted mean or standard or even from an average

for their kind and therefore approaching what may be called

pathological.

The desire to explain the abnormal has had the effect, during the half

century since Virchow defined cellular pathology and Darwin systematized

the world’s knowledge of comparative biology, of directing attention to

comparative pathology and of stimulating the study of veterinary

medicine. Moreover in the past twenty-five years much work has been done

and many isolated publications have appeared upon the diseases of wild

animals, notably Bland-Sutton’s work, _Evolution and Disease_ (1895), a

thoroughly scientific and most charmingly written book, but rather

elementary in its approach of the subject of pathology, and Wood

Hutchinson’s _Diseases of Animals_, a more or less popularly presented

treatise. I am unaware, however, of any systematic monograph upon the

subject wherein we may find data showing the character of pathology in

the various animal groups or the incidence of the various lesions. The

reports of some zoological gardens contain the result of medical and

pathological data collected for the report period. The publication of

greatest merit and value is that from the Zoological Society of London,

whose huge collection studied by a large official personnel makes it

possible to present valuable data. The New York Zoological Park uses its

material in a similar manner and has been able to explain some of the

knotty problems so frequently met in wild animal collections.

Here at Philadelphia it has been our practice now for twenty years to

perform an autopsy upon every mammal and bird that dies, and upon all of

the large or important reptiles. There is no aquarium connected with the

Garden. The office of the society keeps a record of the arrival and a

general description of every animal so that a brief history of the

specimen is usually available. The keepers are required to observe their

charges regularly and closely and to report any abnormalities to the

officials of the Garden. Somewhat detailed discussions upon signs of

sickness will be given at appropriate places, where also a few remarks

upon treatment will be included, but as this work is not intended to be

a treatise on therapy and since this subject does not differ from that

referable to domesticated animals, little space will be devoted thereto.

Upon death a complete autopsy is performed and the findings are recorded

upon a printed form from which, when the histological, bacteriological

and parasitological studies have been completed, a set of cross index

catalogue cards are typed; these are divided into the principal

diagnoses and determinations. The report of the Zoological Society,

appearing at the end of their fiscal year, February 28th, contains a

résumé of the observations for the year, together with notes of

interesting cases and experimental work.

There have accumulated the records of nearly six thousand autopsies and

upon them as a basis has been founded the following report of the

incidence and nature of pathological manifestations in the various

animal groups, using also as additional data, published reports from

other gardens. The book might be described as a collection of our

studies, parts of which have appeared as separate articles, but most of

which are entirely new, put together with as much connection as the

subject matter will permit. The zoological and pathological literature

has been consulted very extensively, but except for the reports of

zoological societies and the publications of special students, it

usually represents isolated notes by travellers and veterinarians so

that many articles may have been overlooked. Therefore no claim of

perfect completeness of reference is made, the statements resting

chiefly upon our own records. The subject will be approached from the

standpoint of description and incidence, but it is inevitable that

comparisons and contrasts must be noted.

Into the realm of evolution[1] I shall not venture because I appreciate

a lack of adequate preparation for such an attempt, and because, even if

such were not the case, the material at hand is lacking in data upon

fishes, many kinds of reptiles and invertebrates.

A direct and practicable application of these data will be in the

direction of explaining some of the pathological states in domestic

animals and man. There are indeed many disease entities or syndromes in

these groups for which no useful hypothesis has been advanced, while for

others a partial explanation has been offered, usually, however,

inadequate wherewith to form the basis of rational prevention or

therapy. Thus, for example, essential emphysema seems to be limited to

the animals of civilization; on the other hand, the anatomical basis of

exophthalmic goitre may be seen throughout nearly the whole animal

kingdom yet the clinical phenomena belong characteristically to man, and

are occasionally seen atypically in the dog. While it may be impossible

to give a complete comparative anatomy and physiology for each of the

pathological states, the attempt will be made to treat all subjects

analogically through the zoological orders.

The experimental pathologist may find the records of the Garden useful

in his work. For example, he can know that rodents are not prominent

among the orders showing spontaneous arteriosclerosis, but that

nephritis occurs among them in about a quarter of natural deaths; or he

may learn that the Primates have a good cardiac reserve while the

Marsupialia have not. Too often experimental work is not based upon

facts including natural probabilities.

A collection of pathological data such as is presented in the following

pages may be of assistance to veterinarians and managers of zoological

gardens in the diagnosis of sickness in animals, both wild and

domesticated. We do not presume to offer a system of veterinary

medicine, but it is possible to introduce certain objective findings of

practical hygienic and therapeutic value. Such observations are,

however, limited and in our experience at the Philadelphia Garden the

diagnosis of disease in a wild animal, excepting of course those which

are perfectly self-evident, is more often speculation and conjecture

than at all well grounded. It is not uncommon for animals to come to

autopsy presenting a perfect galaxy of abnormalities, yet the closest

antemortem observation failed to reveal unusual conduct or appearance.

On the other hand specimens are frequently opened whose organs fail to

contain any lesions discoverable even by careful study. Dr. Henry

Chapman, sometime prosector to the Society, once made a remark in this

connection—“Why do they die or how can they live so long.” Space is

given to this phase of the observation of wild animals in order to

emphasize the difficulties of interpreting their conditions, but of

course it should be understood that certain data of value may be gained

by close attention to the details of their normal behavior and to

changes which occur indicating that something is wrong.

The naturalist and the trained animal keeper are, in our opinion, better

judges of a wild animal’s condition than is the veterinarian, unless he

be at the same time a zoologist and have long experience with a

menagerie. My own observation of dogs and horses leads me to think that

more acumen is needed to interpret the actions of wild animals since

they seem to have greater natural reserve, and of course in regard to

them there are many more variables since we see fewer specimens of each

species than we know familiarly among domestic varieties. The principal

objects for observation are, as in veterinary medicine, the eyes, the

hair and skin, the mucous surfaces, the droppings, the condition of the

abdomen, the appetite and the desire for water. Physical examination is

limited to tractable beasts and those which can be caught and handled

without danger to the personnel or unusual fright and damage to

themselves. In the interpretations of physical signs in tractable

animals, such as many ungulates and some monkeys, the experience of the

trained veterinarian is of the greatest value, but this fails amongst

carnivores and birds. It might be said that anesthetics could be used

for a thorough examination, but this would be undesirable for a

seriously sick animal and it is, in our experience, none too safe a

procedure although often perfectly practicable. Animals do not like to

be molested much as they may seem to enjoy attention, and when it is

possible it is our practice to avoid handling them.

It might be contended that observations upon diseased states in captive

animals would not represent natural developments, in other words, not

that which occurs in the wild. Such indeed may be true in regard to the

infectious diseases, but since we are imperfectly informed as to the

pathology of the wild state, we are obliged to accept and use the best

substitute at hand. Moreover it seems perfectly fair to consider as

characteristic for an animal or group, the physical and even

physiological expressions of morbid agencies as we know them, even

though the animals be at the time under conditions not natural to them.

It would be perhaps incorrect to say that cirrhosis of the liver occurs

in .6 per cent. of animals in the wild as is the case for our autopsies,

since incorrect food and infections are potent in its causation; on the

other hand, our experience and some few data from naturalists and

pathologists make it conceivable that tumors occur to this number in

native states. The incidence of tumors in wild rodents is quite well

known. Degenerations and fibroses, the result of parasitism, are known

to exist throughout the entire animal kingdom. Further to illustrate how

pathology is distributed in wild life, Plimmer’s experience[2] with 500

rats (_M. decumanus_) might be cited. He found the following: Tubercle 3

times, tape worm cysts 10, Tryp. lewisi 49, empyema 2, tumor of jaw from

old injury 1, pleuritis and hydrothorax 1. Bacteria were found in 71

rats, 40 times in the lungs, 31 times in the spleen; saccharomyces were

found 16 times in the lungs. Dr. W. L. Abbott reports to us personally

that he has repeatedly found coiled exproventricular worms in the wild

specimens he has collected. Not only are we informed of some isolated

and individual pathological states but the existence of epizoötics of

communicable disease among wild life is well authenticated. The simple

citation of the extermination of deer in one section of Colorado by

pleuropneumonia will suffice to illustrate this point. Other examples

are, however, interesting. The occurrence of changes in the jaw bone

almost certainly those of actinomycosis is reported by Blair, the

specimens being shot in the wild and believed never to have been near

civilization. The white-tailed deer of the Swan River Valley in Montana,

are known to be constant carriers of liver-flukes.

It would seem therefore that it is not unfair to use material gathered

from animals under somewhat unnatural conditions as representing the

reaction of the zoological orders to pathogenic agencies. Such

conclusions must however be made very guardedly, for it is probable that

not over ten per cent. of the total number of mammalian and avian

species are to be observed in captivity. Because of the number of orders

and the great variety of genera included in the present study it is

probable nevertheless that the lesions are fairly representative of the

whole animal kingdom.

However, the numbers and percentages given should be read to indicate

the probabilities and should not be interpreted as implying the

mortality relationships since different varieties have differing powers

of resistance to the same pathological state. The margin of safety in

any given group for one or several different disease entities cannot at

present be stated with any degree of precision but this factor is

doubtless very great. The work of physiologists suggests that there is a

reserve power in the human lung sufficient to sustain life until five-

sixths of the functionating organ is useless, and I shall quote a case

of an opossum wherein only one-tenth of the respirable surface seemed to

have remained; we have repeatedly seen both lungs of a monkey apparently

entirely solid. Such physical vital incompatibilities might be

exemplified by many other cases, but when one reviews the physiological

margin of safety, inexplicable and contradictory instances are equally

numerous. I have seen a male deer run a doe against the fence and butt

her, without result, whereas in an apparently similar occurrence the

animal would be dead in a short time. Numerous instances of slight

enteritis of a short stretch of duodenum or ileum have killed, with

almost nothing to be found microscopically, and on many occasions we

have been chagrined in being unable to discover the cause of death. The

capacity of self-healing is a variable one, but seems in direct

proportion to the quietness and seclusion possible for the animal and

inversely to the chance of bacterial infection.

The effect of captivity has been the subject of much speculation. For

the preservation of health it would seem that animals require periods of

rest and activity, thorough elimination, possibly a moderate exercise of

their procreative functions, but most of all, appropriate food obtained

by the physical effort we term chase. All but the very last condition is

supplied in a measure in well managed collections. The degenerating

effect of the absence of chase must be admitted. An interesting and

suggestive example of this was noted by Mr. Jones at the London

Zoological Gardens. He observed the skull of a lion that had been in

captivity thirteen years, in which the canine area of the face and the

part of the skull acting as the insertion for the seizing and holding

muscles had undergone atrophy while the chewing muscles with their bony

bases had remained normal. Numerous examples of disease atrophy are on

record and those of a physical nature must have counterparts in the

realm of physiology. The size to which an animal will attain cannot be

estimated by the examples seen in menageries. Judging by the accounts of

collectors and hunters and upon the more reliable of the moving picture

displays of wild animals in their native haunts, it would seem probable

that under normal conditions of habitat the average size of wild beasts

is considerably in excess of that in park specimens.

The effect of captivity may also be felt in the direction of reduced

resistance to infectious diseases. Brooks, of the New York Park,

expresses the view that captivity increases susceptibility to bacteria

and causes parenchymatous degenerations. In the latter direction it is

interesting to learn that Seligman of London claims to have seen sudden

deaths in wading and struthious birds from myocardial disease, without

valvular or other lesions, for which he holds the enervating effects of

captivity responsible. It is well recognized that a species may be

unusually susceptible to a disease that it has not encountered in its

phylogenic development. Man illustrates this peculiarity very clearly.

Europeans were found exceedingly susceptible to sleeping sickness when

they went first to the part of Africa inhabited by the tsetse fly, and

the American Indians died in hordes when they met the tubercle bacillus

for the first time. Judging by the ravages of tuberculosis in captive

monkeys a similar susceptibility probably explains the matter for there

are no entirely satisfactory records of this disease among them in the

wild state.

In so far as general susceptibility to infection is concerned, it may be

in part due to one of the artificial conditions of captivity, that of

inbreeding. This influence is undoubtedly very great, both by chance in

families, and by intention on the part of dealers as well as the mating

which occurs in menageries. However, it is not known how far inbreeding

may go in the wild state so that one must be very careful about drawing

conclusions in this particular. Several years ago, at the time we

reported the neoplasms found at the Garden, discussion arose as to the

effect of inbreeding, and thereafter some observations were made in this

direction. With the exception of the hyperplasias of the thyroid, not

certainly of neoplastic nature, in a much mixed-up family of wolves, we

could find no evidence that inbreeding was responsible for tumors.

Plimmer and Murray of London, seem to imply that some of their inbred

animals are likely to have tumors; reference to this matter will be made

later in this book. In so far as diseases of the organic systems are

concerning those of the bones seem to be the only ones in which

inbreeding is significant.

The individual resistance will be reduced of course by the unsanitary

surroundings incident to trapping, shipping and storage, but this need

not affect the figures or pathological tendencies of classes or orders.

The effect of captivity is felt in another way. A very large percentage

of wild life perishes during the first weeks or months after its

capture, and in gardens the heaviest mortality occurs among the recent

arrivals. The London Garden figures that from thirty-three per cent. to

fifty per cent. of their total mortality is in animals that have not

been in the garden six months and that die because they are not yet

accustomed to their new surroundings. It seems to us, both from an

academic and a practical standpoint, that this is a long time and should

afford ample opportunity for the garden to study the specimen and for

the specimen to become acclimated. These early deaths are perhaps to be

ascribed in large part to failure of acclimatization but many are

doubtless the result of infection acquired in the wild, in transit while

in the hold of vessels, at quarantine, or in trains, or at the

establishments of dealers. We have seen a few deaths which have followed

behavior that might be likened to homesickness. Perhaps the age at

arrival has an influence upon the morbidity and mortality of wild

animals, for it is easily conceivable that the young and the very old

might adapt themselves to new surroundings with much less readiness than

the sturdy middle-aged adult. The age of animals upon arrival is very

rarely known, and can only be recorded as “young,” “fully developed,”

and “old.” This will have an effect upon statistics and when possible is

noted in the text, but this is not practicable to the extent we desire.

The meaning of “young,” “adult,” and “old” is not the same throughout

the animal orders nor even within orders.

Mitchell[3] has attempted to gain concrete ideas of the expectancy of

life among animals by analyzing the records of the London Gardens. This

gentleman bases his figures upon known ages and the length of time in

captivity, from a combination of which data the specific viability and

the potential longevity may be estimated. Such results, he admits, can

only be approximate and they show within classes and orders, a decided

lack of uniformity. The terms “specific” and “potential” longevity,

coined by Sir Ray Lankester, apply, for the first, to the average length

of life as it is affected by external conditions and those incident to

procreation, while, if an animal be under ideal conditions it will

attain the potential longevity which is longer than the former. These

considerations have a biological and economic importance, while a

knowledge of the pathology shown by the various groups may help to

explain these durations of life. Contrariwise figures of the expected

longevity may assist us in evaluating youth and senility in the causes

of death but can hardly affect the comparative nature of the lesion.

A résumé of Mitchell’s studies indicates that the higher apes have a

potential longevity and a hardihood much less than man but still upwards

of thirty years. As one investigates lower in monkeys, life periods

become shorter, while in the next order, Lemures, the length of life

rises. Carnivora have a reasonably good vitality, their potential

periods varying from ten years in the foxes to thirty-three years in

bears. Insect eating animals are short lived, three years being a

maximum. The Bat family shows great variations, the greatest life being

not over seventeen years. The Rodentia have long lives compared to their

sizes—twenty years in porcupines, fifteen years in squirrels, thirteen

in marmots, nine in agoutis and capybaras, and three in dormice (which

is also about the maximum for the rat). Hyraces live four years on the

average. Proboscidea, although reputed to live to great age, probably

rarely live a half century and may be said to have an expectancy of

twenty to thirty years. Perissodactyla (horses, tapirs and rhinoceroses)

while they may live half a century, have an average life of between

fifteen and thirty years. The closely related Artiodactyla fall into two

groups, a first comprising antelopes, sheep, goats and deer which rarely

exceed seventeen years, and a second consisting of cattle, camels and

giraffes, which vary in expectancy from eighteen to thirty years. The

smaller members of the Ungulata have in relation to size a relatively

greater viability, the ruminants, however, having on the whole a low

viability. Marsupials vary from a maximum of seven years in the opossum

to eighteen in the wombats, but none of this group has a good viability.

The Aves as a class or if compared according to dietary requirements,

have longer potential ages and better viability than mammals. Passerine

birds average twenty years and many live to sixty, while the Picariæ

approach the former figure but do not have such good viability. Psittaci

and Striges may live a half century but the resistance of the latter is

much reduced by any unfavorable surroundings. The raptatory birds live

fifty years, but their viability is variable. Herodiones have a maximum

expectancy of thirty years and good resistance, while their relatives,

Steganopodes, may live fifty years, and Odontoglossæ have a good

viability, up to twenty years. Anserine birds may live to be fifty, and,

unless conditions are quite unfavorable, have a good resistance. Columbæ

may under good conditions live to be fifty. Gallinaceous birds may only

be expected to survive twenty years, a figure also given for Fulicariæ.

Alectorides may live up to fifty years. Limicolæ, though they do not

thrive in captivity, may live thirty years. Impennes live poorly under

artificial conditions, the greatest record being twelve years, a figure

also holding for Crypturi. Struthiones, if the conditions be right, may

live fifty years.

Because of the variable specific longevities, it is frequently difficult

to decide when an animal is senile. Man is said to be as old as his

arteries, and his span of life nowadays is in the neighborhood of half a

century. Parrots exhibit lesions of the vascular system comparable to

the arteriocapillary fibrosis of human beings, and their expected

longevity is about the same or a little greater. From a study of our

cases of this lesion in parrots it can be said to appear quite early in

life and not to lead to organic disease as it is alleged to do in man.

It is, however, interesting to note that in those animals which are

supposed to have the longest specific lives—elephants, snakes, anserine

and raptatory birds, parrots—there is relatively low mortality and fewer

infectious diseases are encountered. The last part of this statement

should be qualified by stating that anserine birds and parrots are quite

susceptible to mycoses, in all probability from musty food, which raises

their death rate, but as this is accidental and artificial, it can be

excluded from consideration.

In a rough way there is a direct relationship between the size of an

animal and its longevity, but this is not close enough to be a reliable

guide; whales and elephants live a long time, but so do snakes and

parrots. Within orders this relation of size and expected longevity is

more easily seen but is not absolute. I cannot state, according to my

present studies, that there is an unqualified relationship between the

size and expected longevity of an animal and its pathological lesions.

The immediate surroundings and the management of captive animals have a

very direct and important bearing upon the mortality and perhaps upon

the incidence of morbid processes but probably not upon the character of

the latter. A full knowledge on the part of the personnel of a

zoological society concerning the habits and habitat of every animal in

their keeping is essential, to which must be added a group of interested

keepers. In engaging the last, it should not be forgotten that certain

men have “a way” with animals and that others cannot manage themselves.

The enormous literature at the disposal of the naturalists permits

executive officers to formulate a plan of housing and feeding with fair

accuracy for each kind of animal, but of course it is rarely possible to

obtain in sufficient quantity the natural food (_e.g._, ants for

anteaters). In so far as food is concerned it seems that with a few

exceptions like the one just mentioned, the substitutions made at the

zoological gardens are nearly satisfactory. The elements in which the

captive diet is poor are the inorganic salts and vitamins since Dr.

Corson-White, some of whose work is included in a later chapter, has

shown that for those animals which our statistics indicate as most prone

to have rickets and osteomalacia, the available phosphorus and calcium

are low, and one vitamin was also below the desired quantity. In this

regard, however, I am not at all convinced that diet alone will suffice

to explain these degenerative osseous diseases; I shall take this up

more fully later. Careful inspection of all food should be made and

cleanliness (sifting of cereals, protection of meat from flies, etc.),

is indispensable. The mortality among our carnivora has materially

decreased since the horse meat after butchering was placed in covered

galvanized iron pans. There are many problems of feeding, too numerous

to be covered in a survey of this sort, which must be solved, and it is

a credit to superintendents that this they have studied carefully.

There are two problems in the management of animals upon which much

difference of opinion exists, namely the heating of houses and the

material of which cages are made. It seems to be the practice in many

gardens to keep animals very warm. Dr. Chalmers Mitchell states

unqualifiedly that adult animals do not have to be kept warm, and that

even an equable temperature is not demanded, variations in temperature

having a distinctly stimulating effect. However he maintains that they

should be kept dry and must be supplied with a shelter. This is in

accord with the experience at the Philadelphia Garden, since for many

years we have allowed access to the open air all winter to every animal

that could stand it. A large group of macaques has now lived entirely in

an open “band stand” cage for nine years with a lower mortality than in

the rest of the monkey collection, which is permitted to go indoors some

of the time. Occasionally one in poor health is frozen to death, and

healthy ones may lose fingers, toes, or a part of the tail, but the

general condition is so much improved that they present an attractive

exhibit to visitors. Unless a storm be of great severity, wild animals

are usually indifferent to it although they may seek their shelter. Snow

apparently is no source of fear to them, and many enjoy playing in it.

The general principles of the enclosure should be proper lighting, free

access of air, dryness and shelter in time of storm, the last so

arranged that the sleeping place is well protected. Appropriate

arrangements should be made for nocturnal animals, regardless of their

visibility to visitors, if their preservation is of importance.

The hygiene of communicable disease has influenced everyone to use

concrete and metal for cages. These substances are without doubt most

simply kept clean, but they are heat-conducting and remain cold or damp

longer than wood or the ground. It may be claimed that the latter two

cannot be disinfected so well, but this need not militate against their

use. Wood can be disinfected by sunlight or by mechanical cleaning plus

disinfectants, by a blast lamp and by paint. The ground will disinfect

itself if allowed to lie fallow for a time, or it may be turned over

after sprinkling with lime. It is fair to note that the New York

Zoological Garden reduced their mortality, especially from verminous

pneumonia, by changing some deer herds to concrete paved enclosures; if

that were the only change made the result would be very significant, but

it should not be forgotten that another clean ground range might have

served as well to a herd from which the infected ones had died. My own

observations with guinea-pigs, rabbits, mice and dogs lead me to believe

that they thrive and breed better on wooden floors than on metal or

stone.

I have tried to work out figures to show that more animals die when

housed in enclosures of stone and metal than when upon the earth or on

wood, but the attempt has been unsuccessful chiefly because of the

presence of epidemics and parasites, principally among the birds. The

attempt was further embarrassed because some members of an order are

housed on both floorings. However, there was no great advantage for the

metal and concrete floors even after the epidemic had been discounted.

This Garden does not have a great number of pneumonias, a disease said

to be favored by dampness and cold, but those that occur are chiefly

among the small mammals, on wooden floors and in the large bird house in

cages of concrete and metal. However, the construction of both these

houses permits the visitors to approach very close to the cage, a factor

that doubtless explains the disproportionate incidence of inflammation

of the lungs. In so far as outdoor fowl and ungulate ranges are

concerned, they should be changed frequently under the best conditions

since occasionally one will find groups doing badly until moved.

Moreover the ground becomes contaminated with parasites such as

esophagostomum and heterakis, infestation with which while not very

serious in itself, may lead to fatal infection with bacteria.

The effect of animal parasites upon the morbidity and mortality of wild

beasts and birds in captivity is by no means clear, and Doctor Weidman

and I are inclined to be sceptical, with certain reservations of course,

of their great importance in the death rate. Doctor Weidman has kindly

agreed to contribute a chapter upon the general distribution of

protozoal and metazoal parasites with a summary of their probable

pathogenic importance.

The groups known to have a decided pathological power might be divided

into the toxic, the tumor formers and the mechanically obstructive;

certain parasites have properties placing them in two of these classes.

The first group comprises the hemosporidia and hemogregarines, the

uncinaria and some of the cestodes, forms which produce hemolysis and

hemorrhages with varying grades of anemia. The importance of this group

is shown chiefly among the Aves, in which high grades of anemia are

occasionally met from malarial infections, but cats and dogs or even

herbivores also frequently suffer from hookworm. The tumor-producers are

chiefly echinococcus worms, the cysts of which may grow large enough to

occupy nearly the entire abdomen. A certain grade of anemia and general

ill health accompany this hydatid disease, partly the result of a toxin

and partly by damage to important viscera. Those parasites which

obstruct mechanically do so by their own bulk or by an accompanying

inflammation, incited by them as foreign bodies or by bacteria which

have gained entrance at the irritated point. This is exemplified by the

enormous collection of nematodes sometimes found in reptiles (a pailful

was removed from a python) and by the tightly coiled or tangled thread

and tape worms frequently found in birds. The effect of swelling by the

mucous membrane under the influence of worms is illustrated by the

infestation of the proventricle in parrots. Here spiroptera penetrate

into and under the glandular layer which swells and pours out mucus, the

total mass of nematodes, mucus and tissue obstructing the passage.

Very many animals show parasitic infestation at postmortem, but the

percentage in which they can be said to be principal causes of death is

quite small, while that in which they play a rôle as activator of the

terminal condition is also small but indeterminate. The latter group

comprise, together with the anemias mentioned above, certain forms of

pneumonia, of hepatic and vascular lesions. Inflammations of the lungs

from ascaris and paragonimus are fairly well known; fortunately we have

been troubled less with this than have most gardens, possibly because we

do not have such large herds of herbivora susceptible to it. Hepatic

diseases from flukes, from coccidia and from amœbæ we have always with

us in small numbers, but they are unimportant excepting enterohepatitis,

a condition which appears in nearly all orders. This last disease, be it

purely amœbic as in dysentery of man and monkeys, or like blackhead of

turkeys and chickens or in the forms of quail disease, arrests the

attention at once and evokes a desire to explain the association of

large intestines and liver. Parasitic vascular lesions are relatively

unimportant.

Taking parasitic infestations by and large, there are close similarities

throughout the entire animal kingdom, and the effects produced by a

given genus will be repeated almost exactly in several others. The

pathological pictures of anemia, of hepatic degeneration, of cystic

degeneration, of colonic ulceration or of fibroses are similar in

different hosts, only slight variations in the type of inflammation

being noted, for instance in reptiles and birds as against the mammals.

We have made rather close observations upon the effect of parasites in

the production of neoplasms, incited by Fibiger’s discovery of nematodes

in the rat’s stomach cancer, but, with the possible exception of a

papillomatous growth in the stomach of opossums from the action (?) of

physaloptera, we have been unable to establish such an etiological

relationship. A decision of the importance of parasites in any given

case is not without its difficulty, and we are inclined to reserve

judgment pending further analysis unless the effect of the invaders is

unequivocal. Leiper[4] does not seem to credit animal parasites with a

great effect on the mortality after a specimen has been in the

collection six months since all the intestinal varieties he studied came

from animals dying in that period. On the other hand the forms which

invaded the internal organs and tissues were, in his series, from

specimens resident several years in the garden. He seems to think the

conditions of life at the garden favor the expulsion of intestinal

worms. To what extent some intestinal worms may be commensal remains as

uncertain as the value of certain bacteria in the gut tract. In man

considerable importance has been ascribed to certain fermentative and

putrefactive germs in the maintenance of a reaction unfavorable to

strict pathogens and some observers have looked at them as possessing a

digestive power. In the digestive tract of the animals eating large

quantities of carbohydrate as cellulose, nature provides for its use by

rumination and by supplying a large hind-gut, by which means secondary

mastication and bacterial decomposition of the cellulose capsule insures

its full use. Possibly a similar usefulness may be finally ascribed to

some animal microbes or even larger metozoa.

The rôle of vegetable parasites in the causation of disease among wild

animals seems as undoubted as it is in the human being and the

pathologic results are usually as clear, at least for the entities of

which we have exact data, based upon comparisons with man and domestic

animals.

There seems to be no essential difference among mammals between the

pathological pictures of infectious septicemias, the mucous and serous

membrane inflammations and tuberculosis for example. They are

characterized by fibrinous, purulent or infiltrative inflammations which

may go on to necrosis or repair, by fever, by leucocytosis and by

evidences of resistance—all of these things occurring in a similar way

throughout the class. Of course not all animals are receptive to all

infections since specific racial and generic immunities exist, but the

basic response in terms of pathology is similar. There are no normal

means of judging the susceptibility of wild animals on their native

heath to the important pathogens of civilization, pneumococci,

streptococci, staphylococci, cholera bacilli, the typhocolon group, the

Friedlander group and others, but it is interesting to note that in

captive conditions they evince some receptivity to these germs or their

congeners. The pneumococcus takes a fairly heavy toll in zoological

collections every year and the Friedlander bacillus, not a very common

cause of human pneumonitis, has been seen here and at London.

Among the birds, however, quite distinct differences in some

pathological processes occur, not only from the mammals but also within

the class. As a whole birds do not produce pus as we know it in man,

probably because of the absence from their leucocytes of a protein-

splitting ferment; their leucocyte-producing organs do not seem to

respond as readily to a virus, the place of purulent exudate being taken

by a coagulum or necrosis. The former varies from a clear gelatin-like

material seen upon serous surfaces to a thick mat or mass of coarse but

short fibrinous strands. Necrosis may succeed upon the latter or occur

so promptly as to appear like the original form of degeneration. It is

usually rapid, accompanied by a circumferential congestion but not

associated with active phagocytosis. Giant cell production is variable,

but when developed the appearance is like that of large syncytia.

Hemolysis is not marked in the simple infections but a hyperplasia of

the mononuclear nodes of the liver is the rule. The function of this

nodal increase is not quite clear. It has been always thought that the

scanty bone marrow would supply the necessary erythrocytes, but we have

seen these mononuclear areas full of pale red cells fitted with round

nuclei and without pigment. The fibrin mentioned above does not have the

delicate interweaving that we know in a fibrinous exudate in man. This

is interesting when we consider the composition of the blood and its

coagulation in the Aves. The cell upon which human coagulation seems to

depend, the platelet, is represented in birds by the thrombocyte, which

appears only up to about 50,000 per cubic millimetre. Coagulation time

is relatively short and the resulting clot is firm and irregular.

Perhaps this may have something to do with the nature of an inflammatory

exudate.

The response to infection on the part of birds may to some extent depend

upon differences in anatomy, which are quite distinct, not only from the

mammals within which class the anatomy is more uniform, but also from

one avian order to another. These differences among the birds may be

exemplified by the large foramina between lungs and air sacs in the

water birds, a passage which permits infection, notably mycosis, to

spread from the first to the second. Again the close apposition of the

pancreas to the duodenum over a long stretch permits easy infection of

the former from the latter. Still again the large renal-portal vein in

the gallinaceous birds explains some of the infections of the liver

secondary to intestinal disease. The position of the lungs, deep in the

thorax and fitted into recesses made by the sharp anterior border of the

ribs and overlaid anteriorly by a rather firm air sac wall, makes it

difficult for these organs to expand and therefore renders even a simple

congestion a dangerous thing. The position of the ovary subjects the

shell-less egg to much danger from the intestinal area.

These and many other peculiarities of anatomy affect the pathological

picture in birds. To be sure there are also noteworthy differences among

the Mammalia, notably in the intestinal and genital tracts, but the

pathologic response is not so varied as in the birds. When due allowance

is made for the kind of stomach and absorptive area, apparent

differences can be reconciled. For example, there is little confusion

experienced in comparing acute erosive gastritis or the follicular

enteritis of an omnivorous intestinal tract (man or pig), of a

sacculated stomach and absorptive tract (the marsupial), of a

carnivorous gut (cat) or a herbivorous compound stomach with its long

digestive and water-absorbing surface (cow or camel) and an expansive

muscular organ with a very extensive digestive area (seal). The type of

lesion seems the same, in that inflammation, pus, necrosis, granulation

tissue and cicatrices are comparable throughout the series. The size of

the hind-gut has been taken by Metchnikoff as an indicator of the

possibility of intoxication by degradation products of digestion. He

believes that the capacious colon of herbivora and the short small one

in carnivora explain the relatively greater life in the latter, because

here less stagnation and absorption can take place. A reference to the

expected lengths of life given before hardly substantiates this, and in

our later chapters there will be found no strong indication that animals

with large colons suffer with degenerative visceral changes more than

those with small ones; nay even the reverse may be found true.

In regard to epizoötics the behavior of man and lower animals is similar

except perhaps that during an outbreak a smaller percentage of the

latter give evidence of individual immunity and whole groups are apt to

be carried off. Occasionally hygienic measures stay the ravages, at

other times nothing seems to avail. Fortunately it is sometimes possible

to sacrifice infective specimens and remove contagion. We have had few

serious outbreaks, unless one might call our former heavy infection with

tuberculosis in monkeys an epizoötic. The principal ones were an

unexplained water fowl disease which carried off one hundred and forty-

six birds, an imported epizoötic of quail disease which killed about the

same number, a few cases of blackhead among wild turkeys, and a small

group of cases of amœbic dysentery in monkeys and of thrush in passerine

birds, and a small number of tuberculous pneumonias in snakes.

Pathology may be difficult upon an anatomical basis, but when we engage

to explain functional physiological defects we are surely embarked, with

a poor compass and weak rudder, upon an uncharted sea. One knows, of

course, that all animals require the same amount of food elements per

kilo of body weight, that man eliminates his nitrogen as urea and uric

acid, that monkeys do the same, that most other mammals destroy uric

acid and excrete allantoin, that birds and reptiles form uric acid but

chiefly urates, that there is an adaptation of alimentary tract and

diet, that herbivores have a high threshold for carbohydrates, that

there is a variable quantity of enzyme present in different organs and

in different animals, that vitamins, whatever they may be, are necessary

for the growth of young animals, that hormones exist whereby

correlations of parts are kept normal—but these things, rather than

being learned thoroughly from animals, have merely been substantiated by

comparisons with man. Constitutional diseases so-called, from which the

necessity to investigate much of this physiology originated, are little

known in the wild animal. Many cases of so-called gout have been

encountered and we have seen an instance of diabetes in a fox, but more

extensive experience is needed for definite practical comparisons. This

applies to thyroid and pituitary disorders and to the vague conditions

we have at times been obliged to call marasmus or inanition.

Some attention has been given to the study of diets for the wild

specimens of our Garden, but no systematic observations have been made

or records kept upon purely physiological subjects. Reference will be

made at appropriate places to accepted comparative physiological facts,

but our statistics permit additions to such knowledge only in a limited

manner and in isolated instances. Doctor Corson-White has very ably

summarized the diet, alimentary tract and physiology of the zoological

groups with the pathology as found in our records.

A word might be added here as to the destruction of animals by injury

from fighting and harassment by others in the cage. Fighting doubtless

causes death, especially when males are together, but it is our

experience that in cases of traumatic death search should always be made

to see if the resistance of the dead animal had not been reduced by some

disease. This is well illustrated in birds. Very frequently a specimen

will come to autopsy with its head feathers plucked out, or with a

billthrust in the wing or pelvic region. Such birds are not infrequently

suffering from malaria, or heavy intestinal parasitism or from organic

disease whereby the resistance and self-preservatory power has been

decreased.

The foregoing survey of the approach to our subject reveals the

multiplicity of factors which affect the study of comparative pathology.

No one of them can be entirely omitted, no one is without some effect

upon the origin and expression of disease, and no one is fully

understood. Yet it is to be hoped that a study of our material,

accumulated under routine conditions and uninfluenced by any

experimental procedures, will demonstrate the natural response of

various zoological groups to morbific agencies. Perhaps reactively some

of the modifying conditions may thus be understood. It is also not

unreasonable to expect that alterations observed as natural responses in

a large number of specimens in nearly normal surroundings would serve as

more reliable guides to investigative speculation than would changes in

a few animals under artificial technical experimentation. We hope that

the few facts we have been able to record may afford someone a basis for

further biological studies. It is also to be hoped that something has

been learned which in the end will afford an explanation of the diseases

of man. Too great optimism in this direction should be guarded against

because the human being is indeed an animal _sui generis_ and, from the

standpoint of normal conditions of nature, a wild animal.

The zoological classification found on pages 43–46 was compiled in 1903

by Dr. A. E. Brown on the basis of the British System. With a few

exceptions the computations in the text are made on the basis of

zoological _orders_ since the number of specimens in families is often

too small and the complications of so many different figures would be

confusing. The tables will be found to correspond to the sequence of the

classification. Dr. Corson-White has, however, used for her analysis the

dietary groupings. A carnivore in her chapter implies strictly a meat-

eater, in the rest of the book one of the zoological group Carnivora.

The Laboratory of Comparative Pathology at this Garden speaks for the

earnest desire on the part of the Directors to use the material to its

fullest extent, and I, acting for myself and my associates, wish to

record our appreciation of the facilities offered to us for study, and

for the broad-minded, scientific coöperation the Board has always

displayed. The President, Charles B. Penrose, M.D., Ph.D., LL.D., was

the active originator of the plan whereby this department was started,

and he has given to it continuously the support of his rich experience.

I wish to express for myself the deepest appreciation of his personal

interest in my studies, and assistance which has been constructive and

stimulating. Whether or not this present work prove useful to the extent

that is hoped, the results from the Laboratory are such as to make the

scientific world debtor to this gentleman.

It is a duty, and a pleasant one, to record, though unfortunately in

memoriam, my association with Arthur Erwin Brown, A.M., Sc.D., Ph.D.,

C.M.L.Z.S., for many years the Secretary of the Society and Executive

Officer of the Garden. Doctor Brown as teacher was ever ready to help in

the broad subject of biology, and I am proud to recall that he guided me

also as a friend.

The first director of the Laboratory was Courtland Y. White, A.M., M.D.,

who served from 1901 to 1906, retiring then to accept a position in the

City Laboratory. The foundation of the recording system is still in use

essentially unchanged from his plan, and is a credit to his foresight.

Our clerk and technician, Miss Harriet M. Phelps, has served the Garden

faithfully and well since 1906. The condition of the museum is very much

due to her interest and watchfulness. Thanks and appreciation for her

work are felt by every one, the author most of all. Dr. F. D. Weidman

has been our first assistant since 1911, and his work on parasitology

has been of the greatest value, practically and scientifically. It is to

be hoped that we shall be able to retain him indefinitely. Dr. E. P.

Corson-White has in recent years taken an assistant position with us,

armed for the work with a thorough knowledge of applied organic

chemistry and immunology, and has already obtained useful results.

ZOOLOGICAL CLASSIFICATION

│

MAMMALIA

PLACENTALIA

PRIMATES

_Simiadæ_ Anthropoid apes

_Cercopithecidæ_ Old World monkeys (macaques, baboons).

_Cebidæ_ New World monkeys (capuchins, howlers,

spiders).

_Hapalidæ_ New World monkeys (marmosets).

LEMURES

_Lemuridæ_ Lemurs, Loris, Galagos.

CARNIVORA

_Felidæ_ Cats

_Viverridæ_ Civets, Genets, Paradoxures, Ichneumons.

_Hyænidæ_ Hyena.

_Canidæ_ Dogs, Wolves, Foxes, Jackalls, Etc.

_Mustelidæ_ Marten, Skunk, Weasel, Otter, Badger, Etc.

_Procyonidæ_ Raccoon, Bassaris, Coati, Kinkajou.

_Ursidæ_ Bear.

_Otariidæ_ Eared Seal, Sea Lion.│These are grouped

│separately as suborder,

│PINNIPEDIA, illustrating

│water carnivores.

_Phocidæ_ Common Seal, Walrus. │ „

INSECTIVORA

_Tenrecidæ_ Tenrec.

_Solenodontidæ_ Solenodon.

_Talpidæ_ Moles, Shrews.

_Erinaceidæ_ Hedgehog.

CHIROPTERA

_Pteropodidæ_ Fruit Bats, “flying foxes.”

_Vespertilionidæ_ Common bats.

_Emballonuridæ_ Snouty Bats, Free-tailed Bats.

RODENTIA

_Sciuridæ_ Squirrels, Spermophiles, Marmots.

_Castoridæ_ Beaver.

_Muridæ_ Rats, Mice.

_Geomyidæ_ Pouched Rats, “Gophers.”

_Dipodidæ_ Jumping Mice, Jerboas.

_Heteromyidæ_ Kangaroo Rats.

_Octodontidæ_ Capromys, Coypu.

_Hystricidæ_ Porcupines.

_Chinchillidæ_ Viscacha, Chinchilla.

_Dasyproctidæ_ Agouti, Spotted Cavy.

_Caviidæ_ Guinea-pig, Capybara.

_Leporidæ_ Rabbits, Hare.

PROBOSCIDEA Elephant.

HYDRACOIDEA Cape Hyrax.

UNGULATA

PERISSODACTYLA (odd toed)

_Rhinocerotidæ_ Rhinoceros.

_Tapiridæ_ Tapir.

_Equidæ_ Horse, Ass.

ARTIODACTYLA (even toed)

_Bovidæ_ Oxen, Antelopes, Sheep, Goats.

_Cervidæ_ Deer, Moose, Elk.

_Antilocapridæ_ Prong-horned Antelope.

_Giraffidæ_ Giraffe.

_Tragulidæ_ Chevrotains, Muis Deer.

_Camelidæ_ Camels, Llama.

_Hippopotamidæ_ Hippopotamus.

_Suidæ_ Swine, Warthogs.

_Tayassuidæ_ Peccaries.

SIRENIA Sea-cow, Manatee, Durong.

CETACEA Whales, Porpoises.

EDENTATA

_Bradypodidæ_ Sloths.

_Dasypodidæ_ Armadillo.

_Myrmecophagidæ_ Anteaters.

MARSUPIALIA

MARSUPIALIA

_Didelphyidæ_ Opossums.

_Dasyuridæ_ Dasyures, Tasmanian “Devils.”

_Peramelidæ_ Bandicoots.

_Phascolomyidæ_ Wombat.

_Phalangeridæ_ Phalangers.

_Macropodidæ_ Kangaroo, Wallabies.

MONOTREMATA

MONOTREMATA

_Echidnidæ_ Echidna, Ornithorhynchus.

AVES

PASSERES

_Turdidæ_ Thrushes, Robins, Etc.

_Sylviidæ_ Warblers, Kinglets.

_Paridæ_ Titmouse.

_Troglodytidæ_ Wrens, Mockingbirds, Catbird, Etc.

_Pycnonotidæ_ Bulbul.

_Crateropodidæ_ Babblers, Jay-thrushes.

_Oriolidæ_ Oriole.

_Motacillidæ_ Wagtails.

_Dicruridæ_ Drongos.

_Mniotiltidæ_ Chats, Warblers, “Woodwarblers,” Etc.

_Cœrebidæ_ Sugarbirds.

_Vireonidæ_ Vireos.

_Laniidæ_ Shrikes.

_Ampelidæ_ Waxwing.

_Hirundinidæ_ Martins, Swallows.

_Meliphagidæ_ Honeyeaters.

_Tanagridæ_ Tanagers.

_Ploceidæ_ Weavers, Whydah birds, Waxbills, Finches, Etc.

_Fringillidæ_ Finches, Sparrows, Buntings, Grosbeaks, Etc.

_Icteridæ_ Hangnests, Troupials, Grackles, “Blackbird,”

Etc.

_Sturnidæ_ Starlings, Mynahs.

_Corvidæ_ Crows, Jays, Magpies, Jackdaws.

_Alaudidæ_ Larks.

_Tyrannidæ_ Tyrans.

_Cotingidæ_ Bellbird, Cock-of-the-rock, Etc.

PICARIÆ

_Upupæ_ Hoopæ.

_Trochilidæ_ Hummingbirds.

_Cypselidæ_ Swifts, “Chimney Swallow.”

_Caprimulgidæ_ Night hawk, Whip-poor-will.

_Coraciidæ_ Roller.

HALCYONES

_Alcedinidæ_ Kingfisher.

_Momotidæ_ Motmots.

BUCEROTES

_Bucerotidæ_ Hornbill.

TROGONES

_Trogonidæ_ Trogons.

SCANSORES

_Picidæ_ Woodpeckers.

_Rhamphastidæ_ Toucans.

_Capitonidæ_ Barbets.

COCCYGES

_Cuculidæ_ Cuckoos.

_Musophagidæ_ Touracous.

PSITTACI

_Loriidæ_ Lories, Lorikeets.

_Cacatuidæ_ Cockatoos.

_Psittacidæ_ Macaws, Conures, Amazons, Parrots, Parrakeets.

STRIGES

_Strigidæ_ Barn owl.

_Bubonidæ_ All other owls.

ACCIPITRES

_Falconidæ_ Buzzards, Hawks, Falcons, Eagles, Etc.

_Serpentaridæ_ Secretary Vulture.

_Catharidæ_ Vultures.

COLUMBÆ

_Treronidæ_ Fruit pigeons.

_Columbidæ_ All other pigeons and doves.

PTEROCLETES

_Pteroclidæ_ Sand grouse.

GALLI

_Tetraonidæ_ Grouse, Ptarmigans.

_Phasianidæ_ Pheasants, Fowls, Turkeys, Quail, Etc.

_Cracidæ_ Curassows, Guans, Etc.

_Megapodidæ_ Brush turkey.

HEMIPODII

_Turnicidæ_ Hemipodes.

FULICARIÆ

_Rallidæ_ Rails, Porphyrios, Gallinules, Coots, Etc.

ALECTORIDES

_Aramidæ_ Courlan.

_Eurypygidæ_ Sun bittern.

_Gruidæ_ Cranes.

_Cariamidæ_ Cariama “Crane.”

_Psophiidæ_ Trumpeters.

LIMICOLÆ

_œdicnomidæ_ Thicknees.

_Charadriidæ_ Plovers, Sandpipers, Curlews, Woodcocks, Etc.

_Chionidæ_ Sheathbills.

GAVIÆ

_Lariidæ_ Gulls, Terns.

_Stercorariidæ_ Jaeger Gull.

PYGOPODES

_Colymbidæ_ Loons, Grebs.

_Alcidæ_ Auks, Murrs, Puffins.

IMPENNES

_Spheniscidæ_ Penguins.

STEGANOPODES

_Sulidæ_ Gannets.

_Pelicanidæ_ Pelicans.

_Phalacrocoracidæ_ Cormorants.

_Anhingidæ_ Darter “Water turkeys.”

TUBINARES

_Procellariidæ_ Petrels, Fulmars.

HERODIONES

_Ardeidæ_ Herons, Bitterns, Egrets.

_Ciconiidæ_ Storks, Ibises.

_Plataleiidæ_ Spoonbills.

ODONTOGLOSSÆ

_Phœnicopteridæ_ Flamingoes.

PALAMEDEÆ

_Palamedeidæ_ Screamers.

ANSERES

_Anatidæ_ Swans, Geese, Ducks.

STRUTHIONES

_Apterygidæ_ Kiwis, Apteryx.

_Casuariidæ_ Cassowaries.

_Struthionidæ_ Ostriches.

_Rheidæ_ Rheas.

CRYPTURI

_Tinamidæ_ Tinamous.

_List of Animals subjected to

Autopsy giving the number of

each. These Figures are used to

obtain the percentages quoted

in the Tables and Text._

MAMMALIA

Primates 498

Lemures 86

Carnivora 481

Pinnipedia 20

Insectivora 6

Chiroptera 5

Rodentia 198

Ungulata 365

Proboscidea 3

Hyracoidea 7

Edentata 16

Marsupialia 175

Monotremata 0 1860

————

AVES

Passeres 1355

Picariæ 87

Striges 133

Psittaci 689

Accipitres 196

Columbæ 157

Pterocletes 0

Galli 299

Hemipodii 2

Fulicariæ 35

Alectorides 37

Limicolæ 6

Gaviæ 20

Pygopodes 0

Impennes 5

Steganopodes 21

Tubinares 0

Herodiones 98

Odontoglossæ 6

Palamedes 5

Anseres 317

Struthiones 32

Crypturi 5 3505

———— ————

5365

SECTION II

DISEASES OF THE HEART

The heart is an organ whose duty, throughout the two classes considered

in this study, remains entirely identic, purely a physical one in

driving the blood through the corresponding vascular system. The physics

involved naturally differs between mammals and birds, but energy is

derived from the automatic power lodged in the cardiac musculature.

Whether this be neuromyogenic, as seems to be the case in all mammals,

or purely myogenic, as is probably the case for the birds in which

MacKenzie and Robertson[5] say there is no atrioventricular bundle, the

result is the same, since in both classes there is some continuity of

muscle fibres from auricle to ventricle. The gross anatomy varies little

if any more than the physiology, albeit there is proportionately greater

auricular capacity in the mammals than in the birds, and indeed there

are differences within the classes which cannot now be readily

explained; certain minor variations of valvular arrangement exist, such

as the absence of the membranous light tricuspid in Aves.

When, however, one considers the cardiac power available for various

animals, the subject becomes one of greater breadth and complexity, for

no consistency obtains even within families, since the demand for

cardiac strength will vary more with habits than with zoological

relationships. Thus for example the domestic rabbit has a small heart

volume while the wild hare has a great one. Although, of course, the

size of an organ may not be an absolute measure of its efficiency (a

flea’s leg muscle has relatively greater power than a man’s), yet size

is the only physical gauge one has for estimating nature’s preparation

for expected demand. Perhaps this will be shown later when after

discussing the pathological anatomy of the heart in the wild mammals and

birds, we can study these changes in light of statistics upon the

relative size of the heart.

EXPRESSION OF CARDIAC DISEASE.

The diseases of this organ are known only by their physical effects,

chiefly by causing physical or functional defects in other organs and to

a minor degree by purely physiological irregularities in the heart

itself (tachycardia, arrhythmia). All the latter and most of the former

are subjects discovered by observation during life and unfortunately

cannot be included in the study at hand. Both states are well known to

the veterinarian who diagnoses them with reasonable ease in animals that

can be handled; I saw one case of arrhythmia in a monkey for which no

adequate gross morbid explanation was found postmortem. Some of these

functional abnormalities are certainly caused by myocardial disease and

cardiac failure has occurred among many orders. An interesting

observation was made by Plimmer[6] on several large birds (ostriches,

storks, cassowaries) which apparently died from this condition; at

autopsy he found myocardial degeneration, or epicardial edema or only a

flabby heart. Lack of exercise was held responsible by this observer.

Such cardiac deaths have probably been encountered at this Garden but we

have accounted them to shock, or gastrointestinal disease; this matter

will be discussed on a later page.

CORONARY ARTERY DISEASE.

If a degenerative sclerosis of coronary vessels be the cause of angina

pectoris then perhaps paroxysms of this kind occur, for we have seen

such anatomical changes in the heart of three widely separated varieties

of animals, a Nylghaie, a Hamadryas Baboon, a Macaque, and a Brown

Pelican. The history of these animals does not register anything

resembling the clinical picture of angina pectoris in man, and they did

not come to their death from the arterial changes in the heart alone

since sufficient other pathology also existed.

KINDS OF PATHOLOGICAL CHANGE.

As an introduction to the strict pathology of the heart it might be well

to outline the headings of the scheme upon which it seems desirable to

study the subject. It is hardly profitable to take up seriatim the

ordinary general pathological processes as discussed in systems of

pathology for it is our purpose to show the distribution of basic

aberrations from the normal in terms of zoological position. To this end

one must consider the response of the heart (a) to damaging influences

and (b) to a demand for increased work. In the first group come

degenerations and inflammations, upon which may succeed an incompetency

in the form of dilatation. The response of the normal heart to any

physical demand greater than customary has usually been thought to lie

in the direction of hypertrophy, but on occasion it has seemed to be in

the form of dilatation, especially if the strain has been sudden and

severe. Starling thinks that the primary and normal reaction of the

heart to physical strain is always dilatation. The idea of hypertrophy

must not be confused with an understanding of the relatively large

hearts in animals whose habits demand great cardiac power, for then it

is their norm and might be called “physiological cardiac hyperplasia.” I

shall use the terms “increased muscle bulk” and “increased chamber

space” as preferable to hypertrophy and dilatation; this also focuses

attention upon the two features of an enlarged heart.

DEGENERATIONS AND INFLAMMATIONS.

Degenerative changes in disease are recorded in our system as amyloid,

hyaline, fatty metamorphosis, granular and cloudy degeneration. While

there is perhaps between some of these conditions and true myocarditis a

matter only of degree, the records have been analyzed as filed and

perhaps some lessons can be learned from the responses of the various

zoological orders. In the accompanying Table 1 will be found the

distribution of degenerative and inflammatory lesions through the

zoological orders. The percentages speak for themselves but deserve as

well some consideration from the standpoint of normal heart value; this

will be taken up later after the other lesions have been discussed.

TABLE 1.

_Table Showing Incidence, in the Orders, of Degenerations and Inflammations,

or in Other Words the Response to Infectious and Toxic Agencies._

════════════╤════════╤═══════╤════════╤════════╤════════╤════════╤══════════

Heart of │Degener-│Myocar-│Pericar-│Endocar-│Total[7]│ Cases │Percentage

│ ations │ ditis │ ditis │ ditis │ │followed│in deaths

│ │ │ │ │ │ by │per order

│ │ │ │ │ │dilation│

────────────┼────────┼───────┼────────┼────────┼────────┼────────┼──────────

Primates │ 8│ 12│ 18│ │ 38│ │ 7.6

Lemures │ 1│ │ │ │ 1│ │ 1.2

Carnivora │ 19│ 14│ 11│ 10│ 54│ 5│ 11.

Pinnipedia │ 2│ 1│ │ │ 3│ │ _15._

Rodentia │ 5│ 7│ 6│ │ 16│ │ 8.

Insectivora │ │ │ │ │ │ │

Chiroptera │ │ │ │ │ │ │

Proboscidea │ │ 1│ │ │ 1│ │ _33._

Hyracoidea │ │ │ │ │ │ │

Ungulata │ 3│ 9│ 8│ 2│ 20│ │ 5.4

Edentata │ 2│ 3│ 1│ │ 7│ │ _44._

Marsupialia │ 12│ 5│ 6│ 12│ 33│ │ 19.

Monotremata │ │ │ │ │ │ │

│ │ │ │ │ │ │

Passeres │ 4│ 4│ 9│ 2│ 19│ │ 1.4

Picariæ │ 2│ 1│ 3│ │ │ 6│ 6.7

Striges │ │ │ 1│ │ 1│ │ .8

Psittaci │ 10│ 7│ 7│ │ 24│ │ 3.4

Accipitres │ 2│ 19│ 8│ 7│ 36│ 1│ 18.3

Columbæ │ 2│ 1│ │ │ 3│ │ 2.

Pterocletes │ │ │ │ │ │ │

Galli │ 4│ 10│ 13│ 1│ 28│ 1│ 9.3

Hemipodii │ │ │ │ │ │ │

Fulicariæ │ 2│ │ 1│ │ 3│ │ 8.6

Alectorides │ │ 1│ 1│ │ 2│ │ 5.4

Limicolæ │ │ │ │ │ │ │

Gaviæ │ 1│ 1│ │ │ 2│ │ 10.

Pygopodes │ │ │ │ │ │ │

Impennes │ │ 1│ │ │ 1│ │ 16.

Steganopodes│ │ 1│ 2│ 1│ 4│ │ _20._

Tubinares │ │ │ │ │ │ │

Herodiones │ 1│ │ 1│ 2│ 4│ │ 4.1

Odontoglossæ│ │ │ │ │ │ │

Palamedes │ │ │ │ │ │ │

Anseres │ 16│ 17│ 11│ 6│ 50│ 1│ 15.7

Struthiones │ 2│ 3│ 5│ 1│ 11│ │ _34._

Crypturi │ │ │ │ │ │ │

────────────┼────────┼───────┼────────┼────────┼────────┼────────┼──────────

Total │ 98│ 118│ 112│ 44│ 367│ 8│

════════════╧════════╧═══════╧════════╧════════╧════════╧════════╧══════════

In this and subsequent tables, figures in italics are for small groups

of animals coming to autopsy, usually less than one hundred, and from

which percentages may be misleading. The number of autopsies upon such

groups may be found by consulting the list given on page 47.

ENDOCARDITIS, MYOCARDITIS.

Romberg said in his classical work on the heart that there is always

some form of myocardial disease with endocarditis. The 44 cases of

valvular disease detected at this Garden are 15 of chronic nature, 29 of

acute or subacute character. In the former, the chronic, 9 showed some

grade of muscular involvement, while 21 of the 29 acute cases of

valvular inflammation were accompanied by myocardial damage; the

percentages are 60 for chronic and 72 for acute, a relation that would

be expected if one credit the theory that many valvular inflammations

start at the root of the valves, but, at all events, they indicate that

after the acute stages have passed the myocardial damage may be

repaired.

[Illustration:

FIG. 1.—VEGETATIVE AND ULCERATIVE ENDOCARDITIS OF AORTIC VALVE.

OSTRICH (STRUTHIO AUSTRALIS). ORGANISMS ISOLATED CORRESPONDED

CLOSELY TO BAC. AFANASIEFFICHESTER.

]

The large number of cases of endocarditis among the Carnivora,

Accipitres, Anseres and Marsupialia is noteworthy and can hardly be

explained by other argument than a special vulnerability of this organ

in these groups. However, the unusual number of cases in our only native

marsupial, the opossum, seems worthy of a special note since ten of the

twelve instances in the order Marsupialia affected this particular

animal. When seen these ten cases were acute in five instances, subacute

in three and chronic in two. The Streptococcus pyogenes was isolated in

three of the five acute cases; bacteriology of the others was negative

or not done. All of the acute and one of the subacute cases were

combined with some evidence of general septicemia. The type of lesion

was in no way peculiar, unless the facts that all were vegetative when

acute and markedly deforming when chronic, be noteworthy. In two chronic

aortic cases the valvular orifice was almost closed, yet the left

ventricle could not be considered as greatly hypertrophied and no

dilatation existed. In one acute aortic and mitral case, general

dilatation existed. The mitral was involved nine times, three times

alone, four times with the aortic, once each with the tricuspid and

pulmonary. Once the vegetations were limited to the mural endocardium.

Nine of these animals came from one enclosure over a period of two and a

half years, during which time other opossums died from similar bacterial

infections (pneumonia) despite repeated cleansing of the place. No

unusual number of cases of this or similar kinds occurred elsewhere in

the Garden at this time, but it would seem that we had in this cage a

continued bacterial infection.

UNUSUAL PERICARDIAL CHANGES.

The appearance of a stiff gelatinous exudate in the pericardial sac has

attracted our attention on ten occasions (8 birds, 2 mammals). The

substance seems quite homogeneous and almost entirely acellular. One

specimen became solid on heating and another became turbid when put into

Kaiserling’s fluid. In two cases bacterial cultures were made; nothing

grew. It has not been associated with tuberculosis or tumors nor has any

one pathological lesion more than another appeared to accompany it.

A peculiar lesion occasionally seen in birds is “uratic pericarditis” a

process not infectious at all, according to Plimmer, but due to renal

disease. It has been seen here in association with retention of urates

in the kidney, with gout of birds, and apparently quite independent of

any renal or constitutional disease. Both layers of the sac are pearl

gray or irregularly salted with a whitish granular material so that they

are entirely opaque; occasionally the distribution is spotty. The

deposit does not seem to penetrate the myocardium. There is at times

some involvement of other serosæ, but this is usually much less marked

than around the heart. It does not seem that this of itself should be

fatal, but it has been the most decided pathological factor in some of

the autopsies.

Aside from pericarditic exudates, twenty-one instances of pericardial

effusion have been encountered. They offer little that is peculiar in

etiology, chemistry or cytology, but as there has been some question of

the position of the accumulation of the fluid in human beings, it might

be well to note the position in our material. It is recognized in

veterinary medicine that the cardiac dullness is increased especially to

the right, and that most of the fluid will be on that side and

posteriorly. At our autopsies on mammals this is the position usually

occupied by the fluid, the apex being covered by pericardium, unless the

quantity be great enough to make the sac taut, and this position is

retained whether the animal be laid upon the one side or the other; nor

does the fluid all leave the base of the heart when the body is placed

prone. The crown of the heart is nearly always well covered. In birds,

on the other hand, the fluid occupies the apical part of the sac,

probably due to the fact that this membrane is attached by its tip to

the transverse air sac wall which takes the place of a diaphragm, so

that the tip of the heart is always free and the pericardium of the base

fairly closely applied to the epicardium. This holds good even for the

birds whose cardiac apex is normally attached to the pericardium by a

fibrous band.

HYPERTROPHY AND DILATATION.

The response of the heart to a continued demand upon its working

capacity will, as already indicated, lead to increased muscle bulk or to

larger chamber size. Whether hypertrophy be purely the building of a

bigger engine or be accompanied by, or due to, muscular disease as had

been suggested by certain authors, was a question to which an answer was

hoped, but it would seem that the solution is no nearer than can be

obtained in human pathology. Fifteen of the 34 cases showed some degree

of myocardial damage. Some of the other cases may have been instances of

so-called essential hypertrophy, enlargements due to hard work or to low

grade hidden infection. Aubertin[8] ascribes such cardiac muscle

increase to overwork under the stimulus of intoxication from intestinal

sources or from irregular constitutional functions. For information

concerning this and pathological enlargements one may consult the Table

(2) of Hypertrophies and Dilatations; in advance the method of charting

must be known. Since it is usually impossible to decide what may be the

single important factor in the cardiac disease, all of the accredited

factors have been listed with the hope that the resulting figures would

be significant. Thus an animal may have recorded pericarditis, nephritis

and arteriosclerosis—who shall say which was primary or most potent in

the cardiac change.

Essential hypertrophy is limited to those cases for which there was no

concomitant pathology that might have been responsible for the

overgrowth. There was one in a carnivore (fox) and one in a raptatory

bird (buzzard). Idiopathic dilatations on the other hand are much more

common, but they still bear a relation to the apparent vulnerability of

the heart. Their distribution is as follows: Primates 1, Carnivora 1,

Pinnipedia 1, Ungulata 1, Marsupialia 4, Anseres 1. These may be cases

such as Plimmer described, of cardiac failure, indicated by dilatation,

the result of inactivity. Besides these special instances and the ones

accounted for in the list, there were three acute dilatations apparently

due to shock, two ungulates and one marsupial, probably incidental to

fright when being caught by the keepers.

The association of secondary dilatation with hypertrophy is only evident

in three instances. One case and perhaps the most interesting, is that

in which the principal antecedent pathology was thyroid hyperplasia and

nephritis; the dilatation was perhaps agonal or shortly before the last

struggles. It would seem that all of the dilatations occurred shortly

before death because long standing passive congestions and dropsies of

cardiac origin are exceedingly rare; only one certain case is recorded

(carnivore).

Let us now examine the Table (2) according to orders and then as to

causation. The Primates’ heart is apparently well able to increase in

size in response to increased work, a demand most often made by

pulmonary, pleural and pericardial diseases. Two of these cases occurred

in animals suffering with pulmonary tuberculosis sufficiently extensive

to impede cardiac action while in another case the tuberculous lesion

was mild but a pericarditis existed. When the right hand columns are

inspected it would seem that on occasion dilatation may occur; one of

the tuberculous pulmonary cases had a dilated heart. The slothful lemurs

apparently have no call upon their cardiac mechanism.

Carnivora with their large organ, which, it would seem, should be

prepared for excess work either simply as a reserve or as an inherent

ability to grow, present in about equal numbers, hypertrophy and

dilatation. It is admitted that there are within this order, genera of

differing habits, but analysis of the canidæ, felidæ and ursidæ for

examples, in the first place, offer too few specimens for conclusions

and, secondly, have upon trial actually shown nothing definite, so that

we are forced to use the larger group, the order. It is interesting to

note that long continued infection is in this order the most potent

factor in enlargements of the heart. Four of the ten cases show

myocarditis. Nephritis does not seem very important in relation to

cardiac muscular increase, but occurs with great frequency in

association with dilatation. Three of the cases of hypertrophy were

associated with thyroid disease and two of these showed dilatation as

well. The general causes of chamber distention are more diverse, and we

see associations that do not appear with hypertrophy, namely

arteriosclerosis and diseases of the chest.

TABLE 2.

_Table Showing Incidence per Order of Hypertrophy and Dilatation, and

the Principal Associated Lesions Believed to Have Etiological

Importance._

═════════════╤═════════════════════════════════════════════════

Heart of │ Hypertrophy

─────────────┼─────┬────────┬────────┬────────────────┬────────

„ │Total│Percent.│Valvular│Arteriosclerosis│Diseases

│ │ for │Disease │ │ of

│ │ Order │ │ │Thoracic

│ │ │ │ │ Serosæ

─────────────┼─────┼────────┼────────┼────────────────┼────────

Primates │ 4│ .8│ │ 1│ 3

Lemures │ │ │ │ │

Carnivora │ 10│ 2.1│ 1│ │

Pinnipedia │ │ │ │ │

Rodentia │ │ │ │ │

Insectivora │ │ │ │ │

Chiroptera │ │ │ │ │

Proboscidea │ │ │ │ │

Hyracoidea │ │ │ │ │

Ungulata │ 4│ 1.2│ │ │ 1

Edentata │ │ │ │ │

Marsupialia │ 1│ .6│ 1│ │

Monotremata │ │ │ │ │

Total Mammals│ 19│ │ 2│ 1│ 4

│ │ │ │ │

Passeres │ │ │ │ │

Picariæ │ 1│ 1.1│ │ 1│

Striges │ │ │ │ │

Psittaci │ │ │ │ │

Accipitres │ 8│ 4.1│ │ 4│ 1

Columbæ │ │ │ │ │

Pterocletes │ │ │ │ │

Galli │ 2│ .7│ │ 1│

Hemipodii │ │ │ │ │

Fulicariæ │ │ │ │ │

Limicolæ │ │ │ │ │

Gaviæ │ │ │ │ │

Pygopodes │ │ │ │ │

Impennes │ │ │ │ │

Steganopodes │ │ │ │ │

Tubinares │ │ │ │ │

Herodiones │ │ │ │ │

Odonotoglossæ│ │ │ │ │

Palamedes │ │ │ │ │

Anseres │ 2│ .6│ │ │

Struthiones │ 2│ _6.2_│ │ │ 2

Crypturi │ │ │ │ │

Total Birds │ 15│ │ 0│ 6│ 3

─────────────┼─────┼────────┼────────┼────────────────┼────────

Total │ 34│ │ 2│ 7│ 7

─────────────┴─────┴────────┴────────┴────────────────┴────────

═════════════╤════════════════════════════════════════════════════════

Heart of │ Hypertrophy

─────────────┼─────────┬───────┬─────────┬─────────┬───────┬──────────

„ │Pulmonary│ Renal │ Chronic │ Acute │Thyroid│Myocardial

│ Disease │Disease│Infection│Infection│Disease│ Disease

│ │ │ │ │ │

│ │ │ │ │ │

─────────────┼─────────┼───────┼─────────┼─────────┼───────┼──────────

Primates │ 3│ 1│ 1│ 1│ │

Lemures │ │ │ │ │ │

Carnivora │ │ 2│ 6│ 1│ 3│ 4

Pinnipedia │ │ │ │ │ │

Rodentia │ │ │ │ │ │

Insectivora │ │ │ │ │ │

Chiroptera │ │ │ │ │ │

Proboscidea │ │ │ │ │ │

Hyracoidea │ │ │ │ │ │

Ungulata │ │ 4│ │ │ │ 2

Edentata │ │ │ │ │ │

Marsupialia │ │ 1│ │ │ │ 1

Monotremata │ │ │ │ │ │

Total Mammals│ 3│ 8│ 7│ 2│ 3│ 7

│ │ │ │ │ │

Passeres │ │ │ │ │ │

Picariæ │ │ 1│ │ │ │

Striges │ │ │ │ │ │

Psittaci │ │ │ │ │ │

Accipitres │ │ 3│ 1│ 1│ │ 5

Columbæ │ │ │ │ │ │

Pterocletes │ │ │ │ │ │

Galli │ │ 1│ │ 1│ │ 1

Hemipodii │ │ │ │ │ │

Fulicariæ │ │ │ │ │ │

Limicolæ │ │ │ │ │ │

Gaviæ │ │ │ │ │ │

Pygopodes │ │ │ │ │ │

Impennes │ │ │ │ │ │

Steganopodes │ │ │ │ │ │

Tubinares │ │ │ │ │ │

Herodiones │ │ │ │ │ │

Odonotoglossæ│ │ │ │ │ │

Palamedes │ │ │ │ │ │

Anseres │ │ │ 1│ 1│ │ 1

Struthiones │ │ │ 1│ 1│ │ 1

Crypturi │ │ │ │ │ │

Total Birds │ 0│ 5│ 3│ 4│ 0│ 8

─────────────┼─────────┼───────┼─────────┼─────────┼───────┼──────────

Total │ 3│ 13│ 10│ 6│ 3│ 15

─────────────┴─────────┴───────┴─────────┴─────────┴───────┴──────────

═════════════╤═════╤═══════════════════════════════════════════

Heart of │ │ Dilatation

─────────────┼─────┼────────┬────────┬────────────────┬────────

„ │Total│Percent.│Valvular│Arteriosclerosis│Diseases

│ │ for │Disease │ │ of

│ │ Order │ │ │Thoracic

│ │ │ │ │ Serosæ

─────────────┼─────┼────────┼────────┼────────────────┼────────

Primates │ 4│ .8│ │ 1│

Lemures │ │ │ │ │

Carnivora │ 11│ 2.2│ │ 1│ 2

Pinnipedia │ │ │ │ │

Rodentia │ 8│ 4.2│ │ │

Insectivora │ │ │ │ │

Chiroptera │ │ │ │ │

Proboscidea │ │ │ │ │

Hyracoidea │ │ │ │ │

Ungulata │ 11│ 3.│ │ │ 4

Edentata │ 2│ _12.5_│ │ │

Marsupialia │ 8│ 4.5│ │ │

Monotremata │ │ │ │ │

Total Mammals│ 44│ │ 0│ 2│ 7

│ │ │ │ │

Passeres │ 1│ │ │ │

Picariæ │ │ │ │ │

Striges │ │ │ │ │

Psittaci │ 1│ .1│ │ │

Accipitres │ 1│ .5│ │ │ 1

Columbæ │ │ │ │ │

Pterocletes │ │ │ │ │

Galli │ 2│ .7│ │ 1│ 1

Hemipodii │ │ │ │ │

Fulicariæ │ │ │ │ │

Limicolæ │ │ │ │ │

Gaviæ │ │ │ │ │

Pygopodes │ │ │ │ │

Impennes │ │ │ │ │

Steganopodes │ │ │ │ │

Tubinares │ │ │ │ │

Herodiones │ │ │ │ │

Odonotoglossæ│ │ │ │ │

Palamedes │ │ │ │ │

Anseres │ 5│ 1.5│ │ │ 1

Struthiones │ │ │ │ │

Crypturi │ │ │ │ │

Total Birds │ 10│ │ 0│ 1│ 3

─────────────┼─────┼────────┼────────┼────────────────┼────────

Total │ 54│ │ 0│ 3│ 10

─────────────┴─────┴────────┴────────┴────────────────┴────────

═════════════╤════════════════════════════════════════════════════════

Heart of │ Dilatation

─────────────┼─────────┬───────┬─────────┬─────────┬───────┬──────────

„ │Pulmonary│ Renal │ Chronic │ Acute │Thyroid│Myocardial

│ Disease │Disease│Infection│Infection│Disease│ Disease

│ │ │ │ │ │

│ │ │ │ │ │

─────────────┼─────────┼───────┼─────────┼─────────┼───────┼──────────

Primates │ 1│ │ │ 1│ │ 1

Lemures │ │ │ │ │ │

Carnivora │ 2│ 4│ 1│ 2│ 3│ 2

Pinnipedia │ │ │ │ │ │

Rodentia │ 3│ 2│ 2│ 4│ │

Insectivora │ │ │ │ │ │

Chiroptera │ │ │ │ │ │

Proboscidea │ │ │ │ │ │

Hyracoidea │ │ │ │ │ │

Ungulata │ 1│ 2│ 2│ 2│ │ 1

Edentata │ 1│ │ 1│ │ │ 1

Marsupialia │ 1│ 3│ 2│ 2│ │ 1

Monotremata │ │ │ │ │ │

Total Mammals│ 8│ 12│ 7│ 11│ 3│ 10

│ │ │ │ │ │

Passeres │ │ │ │ 1│ │

Picariæ │ │ │ │ │ │

Striges │ │ │ │ │ │

Psittaci │ 1│ │ │ │ │

Accipitres │ │ │ │ 1│ │ 1

Columbæ │ │ │ │ │ │

Pterocletes │ │ │ │ │ │

Galli │ │ │ │ 1│ │ 1

Hemipodii │ │ │ │ │ │

Fulicariæ │ │ │ │ │ │

Limicolæ │ │ │ │ │ │

Gaviæ │ │ │ │ │ │

Pygopodes │ │ │ │ │ │

Impennes │ │ │ │ │ │

Steganopodes │ │ │ │ │ │

Tubinares │ │ │ │ │ │

Herodiones │ │ │ │ │ │

Odonotoglossæ│ │ │ │ │ │

Palamedes │ │ │ │ │ │

Anseres │ │ 2│ 1│ 2│ │ 1

Struthiones │ │ │ │ │ │

Crypturi │ │ │ │ │ │

Total Birds │ 1│ 2│ 1│ 5│ 0│ 3

─────────────┼─────────┼───────┼─────────┼─────────┼───────┼──────────

Total │ 9│ 14│ 8│ 16│ 3│ 13

─────────────┴─────────┴───────┴─────────┴─────────┴───────┴──────────

For meaning of italics see foot note Table 1.

The rodents seem to have no power to increase muscle bulk, but a

sufficient number of cases of dilatation occur to make one conclude that

this is their method of response to unusual strain. Pulmonary disease,

mostly of infectious nature, and myocardial degenerations are the

principal causes.

The next order to show cardiac enlargement is the Ungulata where

nephritis is the most frequent association with hypertrophy and disease

of the pleura and pericardium with dilatation, or the reverse of the

factor value in the Carnivora. These animals, fairly well prepared for

flight, with moderately large hearts, seem more often to show dilatation

than hypertrophy.

Two Edentata (armadillo) showed dilatation but no hypertrophy.

Marsupials behave somewhat like rodents in that the heart does not seem

to increase muscle bulk, but our records do not explain this clearly. As

already mentioned four cases had no sufficient internal reason for

dilatation, but as one was probably the result of shock three only

remain to be accounted for. Nephritis seemed to exist in all three, but

two of them had kangaroo mycosis of the jaw and a general chronic

infection.

If now our attention be given to the Aves we find the highly specialized

Passeres and Striges not represented and their closely related well-

organized orders Picariæ and Psittaci with only an isolated single case.

This is the more interesting since the last order suffers reasonably

often with arteriosclerosis. Accipitres, the birds of pugnacious habit

and carnivorous diet, seem well able to increase their muscle upon

demand, but do not often suffer dilatation. Vascular and renal diseases

stand out most prominently in the etiology, and one-half of them show

myocardial change. The Galli, which includes both ground and flying

birds, are represented but fail to exhibit any unusual accompanying

disease. Anserine birds apparently have a low power to increase the size

of the heart, but most often allow it to dilate. Struthiones, large

stalking and rapidly travelling birds, apparently have a good margin of

safety in their cardiac mechanism.

SUMMARY OF LESIONS ASSOCIATED WITH HYPERTROPHY AND DILATATION.

Analysis of the associated pathology will reveal that among the mammals,

renal disease, chronic infections and diseases of the thoracic serosa

are most often responsible for hypertrophy, and that something over one-

third of the hearts showed myocardial damage. Among the Aves

arteriosclerosis and renal disease are most important in enlarging the

heart; half of the cases had myocarditis. In so far as dilatation in

mammals is concerned, renal disease and acute infections are decidedly

more important than other influences, even than the next in order—

chronic infections and pulmonary diseases; only one-fifth of the cases

had myocardial disease. Acute infectious disease is the most potent

cause of dilatation in birds; only two of the eight cases had

degeneration of the heart muscle.

COMPARISON OF MAMMALIA AND AVES.

If a comparison of the incidence of increased muscle bulk in the two

classes be made[9] it will be found to occur two and one-half times more

often in mammals, while dilatation occurs nearly ten times more often

among the mammals than among the birds. Hypertrophy is accompanied by

myocardial change in 44 per cent. of the cases, whereas muscular

degeneration was only seen in 24 per cent. of the dilatations; this

change is conspicuously lacking in the Primates, Ungulates and

Marsupials. The usual teaching has been that dilatation, which means

enlargement of chambers and thinning of walls or at least no thickening

thereof, implied an inability on the part of the heart to keep up with

increased demand—a decompensation. If Starling be correct that

dilatation is not a degeneration of pump value but merely one of

adaptations to increased demand, then this method is more characteristic

of mammals than of birds. There is, however, the reserve power to

increase the muscle bulk inherent in the mammalian, not possessed or

needed by the avian heart. The large-hearted class Aves certainly dilate

their blood pump less frequently than mammals and indeed have less

cardiac disease.

An analysis of the incidence of hypertrophy _versus_ dilatation shows

that hypertrophying power resides in the Primates, Accipitres and

Struthiones, their hearts relatively seldom dilatating. Lack of such

power and consequent dilatation resides in Rodentia, Ungulata,

Marsupialia and Anseres. Hypertrophying power lies therefore chiefly in

the heart of average size for its class, dilatation occurring in the

small heart. (See page 63.)

AVIAN HYPERTROPHY.

There is little to be learned from the nature and anatomy of the

hypertrophies and dilatations except perhaps their character among the

birds, in which the physics of the circulation is somewhat peculiar. In

this class both the hypertrophy and distention are predominatingly left-

sided, a state probably explained by the pressure against which the pump

must work in flight because then the lungs and the viscera are somewhat

compressed by the pressure of an excess of air in the pneumatic sacs. At

all events while concentric hypertrophy was mentioned once, it is

difficult to estimate the degree of increase in the right chambers

because they are not uncommonly well filled when diastole occurs at

death. Grober[10] asserts that the normally large heart (or what I have

called “physiological hyperplasia”) shows a “hypertrophy” of the right

ventricle because of the extra work entailed in flying. This is

certainly not the case in the material we have seen under pathological

conditions. Right sided increase might be expected if pulmonary or

serous membrane affections were prominent, but left-sided increase,

following arteriosclerosis and nephritis is the actual finding. The best

examples of concentric hypertrophy are in the dogs with thyroid disease

and the best examples of concentric dilatation in ungulates suffering

shock.

SUMMARY.

The foregoing pathological data can now be summarized by grouping the

facts under the headings of absolute and relative vulnerability of the

heart. By the former is meant the actual number and quality of lesions

in the various orders, but here at once one comes upon the irregularity

of examples of zoological and pathological character, and if one trust

entirely to the percentages, fallacious conclusions might be reached.

Basing judgment upon the incidence of pathological lesions in mammals

and birds, it is evident that the former has greater vulnerability, as

13 is to 6.2. This is noteworthy as we shall learn that the bird has a

larger and apparently better prepared heart than the mammal. Attempts to

discover the order or kind of animal having the greatest or lowest

vulnerability are difficult for the reason given above. Thus, for

instance, Pinnipedia, Proboscidea, Edentata, Gaviæ, Impennes,

Steganopodes, and Struthiones present the highest percentages of cardiac

lesions, but the total specimens examined are so few that these figures

may well be misleading. (See Tables 1 and 2.) If, however, figures mean

anything in such small groups, these are the animals which have the

greatest cardiac vulnerability. They have little in common in regard to

zoological relationships and habits; four of the seven orders are rather

slothful and three are active. It is much better to limit our

observations to those orders from which sufficient examples have been

subjected to autopsy and upon which we have some standards for

comparison in the heart-body weight ratio. It so happens that in the

above seven orders I was unable to obtain any reliable figures of heart

weight. Table 3 is a combination of data from Tables 1 and 2 for the

principal orders from which we have enough material (at least one

hundred autopsies) and for which it is possible to obtain as comparative

standards figures indicating the weight of the normal heart in kilograms

of body weight; Table 4 gives these ratios for normal hearts. The

information about the weights was obtained from some of our own figures

and the references given in the footnote.[11] There are no extensive

data upon weights and measures in exact terms, such as body weight, so

that we are limited to the numbers quoted in parentheses besides the

orders in the table. The ratios might be modified slightly by a greater

number of examples, but they show certain things by comparison of the

classes; in a rough manner the heart ratios correspond to the pathology.

TABLE 3.

_Table Containing a Condensation of the Two Foregoing Tables and

Showing Figures for Degenerations, Hypertrophy and Dilatations for

Orders Having the Largest Number of Autopsies._

═════════════════╤═════════════════╤═════════════════╤═════════════════

│ Degenerations, │ Hypertrophy │ Dilatation

│ &c. │ │

─────────────────┼─────────────────┼─────────────────┼─────────────────

Primates │ 7.6│ .8│ .8

Carnivora │ 11.│ 2.1│ 2.2

Rodentia │ 8.│ 0.│ 4.2

Ungulata │ 5.4│ 1.2│ 3.

Marsupialia │ 19.│ .6│ 5.

│ │ │

Passeres │ 1.4│ 0.│ 0.

Picariæ │ _6.7_│ _1.1_│ 0.

Striges │ .8│ 0.│ 0.

Psittaci │ 3.4│ 0.│ .1

Accipitres │ 18.3│ 4.3│ .5

Columbæ │ 2.│ 0.│ 0.

Galli │ 9.3│ .7│ .7

Herodiones │ 4.1│ 0.│ 0.

Anseres │ 15.7│ .6│ 1.5

─────────────────┴─────────────────┴─────────────────┴─────────────────

TABLE 4.

_Table Showing Weight of Normal Heart in

Relation to Body Weight. Number of Specimens

used to Determine Weight Quoted in Parenthesis._

════════════════╤═══════════════════════════════

Average Heart of│Grams per Kilogram of Body.[12]

────────────────┼───────────────────────────────

Man ( 4)│ 5.67

Primates ( 4)│ 6.56

Carnivora ( 6)│ 6.78

Rodentia ( 5)│ 5.

Ungulata (10)│ 5.8

Marsupialia ( 3)│ 5.1

│ Average 5.82

Passeres (43)│ 19.8

Picariæ ( 9)│ 21.3

Striges ( 4)│ 7.33

Psittaci ( 6)│ 8.89

Accipitres ( 7)│ 12.32

Columbæ ( 4)│ 14.47

Galli (16)│ 11.08

Fulicariæ ( 3)│ 23.82

Limicolæ ( 2)│ 8.78

Anseres (14)│ 11.8

Struthiones ( 1)│ 12.7

│ Average 13.84

────────────────┴───────────────────────────────

For meaning of italics see foot note Table 1.

However, there are many reasons why great caution should be used in

evaluating the relative size of the heart. Welcher showed in his work

that the proportion is greater in small and young animals than in large

and adult ones. All the authors quoted agree that in birds and to less

degree but still clearly in mammals, there is a direct relationship

between the bodily activity of an animal and its cardiac bulk. This is

fairly well shown in the list of avian heart ratios, but not so clearly

in the mammals. What shall be considered the most active mammals—the

monkey, perhaps, with his tendency to be occupied constantly, yet we

find the greatest heart bulk among the Carnivora, animals prepared for

travel and struggle, and the smallest among the Rodentia, quiet and

timid animals. The avian order showing the greatest cardiac ratio, the

Fulicariæ, shore birds, is made up of some quiet hiding varieties, and

of some capable of very prolonged flight; the most constantly active

fliers (Passeres) also have a high cardiac weight proportion. The

inactive owls have the smallest heart bulk.

The contrast between the average heart-to-body weights of mammals and

birds is striking, the latter having two and one-half times as much as

the former, 5.8 _vs._ 13.8. Since this is the most prominent and best

supported statement in the table of weights, it may be used to compare

with the incidence of the pathology as seen in the two classes.

Degenerations and inflammations occur in mammals and birds as 9.5 is to

5.5.[13]

Hypertrophies occur in mammals and birds as 10.3 is to 4.3.[13]

Dilatations occur in mammals and birds as 2.4 is to .28.[13]

In other words, mammals are much more susceptible than birds to

degenerative and inflammatory processes, show an ability to increase the

muscle bulk two and a half times as great and are liable to chamber

distention nearly ten times as often. It might also be put that birds

cannot or do not need to increase their muscle, and that the chamber and

muscle balance is more perfectly arranged.

While in the preceding pages hypertrophy has been discussed rather from

the standpoint of its value as a compensating and reserve capacity, and

dilatation as a degenerative or decompensatory process on the part of

the cardiac mechanism, it may be that dilatation of the mammalian heart

is the usual method employed by the class in response to increased

demand. It seems certain, however, that the originally and normally

larger heart, both mammalian and avian, more often uses an increase of

its muscle to this purpose.

Hypertrophy was accompanied by myocardial disease in 44 per cent. of the

cases, while dilatation showed this change in only 24 per cent. This

supports the theory that dilatation is a normal response of the

myocardium under strain and the belief held in many quarters that the

muscle increases its bulk because some of it is damaged.

The differences between classes are not so conspicuous between orders.

However, the large heart of the carnivores increases both its muscle and

chambers, while the small heart of the rodents and marsupials more often

dilates. Analysis of the avian orders is inconclusive and somewhat

contradictory. Let it suffice to say that the birds which fly most, with

exception of the ducks, have a relatively low vulnerability, and the

soaring carnivorous Accipitres and the largest birds, Struthiones,

apparently have a high susceptibility to damaging influences and enlarge

their muscle bulk in response to increased work.

Aneurysms of the heart are quite rare; only two have been seen. They

were both located at the apex of the left ventricle in birds; they did

not rupture. Myocardial damage is evident in both cases but the cause is

not clear; parasites could not be demonstrated. Plimmer reports a case

of cardiac aneurysm at the apex from infestation of the heart muscle by

sarcosporidia.

SECTION III

DISEASES OF THE BLOOD VESSELS

The gross anatomy of the blood vascular system is constructed upon the

same general scheme throughout mammals and upon a comparable basis in

birds. Microscopically there is little variation throughout the orders

unless it be in the relative proportion of muscular and connective

tissues. The origin of the great vessels at their cardiac base and their

distribution to the pulmonary and to the greater circulations in no way

differ in these two classes in that it always consists of an efferent

pathway to the lung and a root vessel above the aortic orifice. The

former has usually quite a distinct origin on the right side, but in

some birds the posterior wall of the pulmonary artery may overlie the

entire aortic base; this, however, is not the rule for birds. The aorta

in most mammals remains a separate and distinct vessel for some

distance, after which it gives off the innominate and subclavians. In

the birds on the other hand, the stretch immediately above the aortic

valve is usually ballooned out somewhat, into a sort of sac or ampulla

from which the subclavians and descending aorta arise. This forms a

structure of rather trident shape, the lateral prongs being the

subclavians, the middle and posterior being the aorta proper. In some

birds the aorta may have the length of a centimetre or more then

dividing into the left subclavian and right aorta from which the right

subclavian comes off.

There is definitely more support to the heart and vascular roots in

mammals than in birds, in the latter class these structures lying quite

free between the lateral air sacs and well in front of the lungs. Nor is

there the richness of mediastinal areolar and fatty tissue in the winged

creatures.

The vessels of mammalia retain a considerable wall throughout nearly

their entire length. At first the wall is thin compared to the calibre

of the vessel while the arteries smaller in calibre, have a heavy wall.

In birds the arterial stalk at the heart is supplied with very heavy

walls, but after the second branching the relation of wall to calibre

seems to continue about the same. In this class the stalk vessels have

wall to calibre relation of 1 to 3 (measurements in 2 Passeres, 1

Psittaci, 1 Accipitres) whereas in mammals the relation varies from 1 to

5 to 1 to 7 (observations on 2 carnivores, 1 ungulate, 2 rodents). In

mammals the consistency of a normal artery wall remains much the same, a

firm, resilient, yellow-white tissue, quite opaque and standing open

upon cross section. In birds this description covers the main stalk, the

aorta in the abdomen and the first part of the carotid and iliacs. When

these characters are lost, the arteries become semitranslucent bluish

strands so that they are difficult to follow in the muscles of the neck

and extremities. This is particularly true in the Passeres, Picariæ,

Galli and Columbæ while in the Psittaci, Accipitres, and Anseres the

arteries are distinctly whiter than the veins but yet quite soft. In the

Herodiones and Struthiones, thick walled vessels may be followed as far

as the second joint in both extremities. These differences depend in

part upon the grosser construction of the central arteries in Aves and

in part upon the larger amount of elastic tissue in them than in the

secondaries and smaller vessels, and than in comparable mammalian

vessels.

It is impracticable to go into the minutiæ of histology in the different

orders, which indeed varies but little, although attention might be

directed to the facts that in all central vessels the relative amount of

elastica is greater than in smaller ones and that muscular tissue seems

to exceed in the latter. Considerable work has been done upon the amount

and arrangement of muscle bands in isolated genera, but no comprehensive

data are at hand upon orders. The strands of muscle do not seem arranged

so regularly as in mammals; the pulmonary artery of the cat, for

example, has a muscle arranged like an oblique band in waves or festoons

along the length. The mammals as a class seem more richly supplied with

arteries and veins than do the birds, and the square area of the

vascular system is likewise larger. This is distinctly different from

the amount of heart bulk as given in the discussion of kilogram-heart

ratios so that one might say that the birds are “overhearted and

undervesseled.”

In so far as the physiology of the two classes is concerned it is

obvious that a different regulatory system is necessary because, aside

from the variations of pressure incidental to pulmonary, muscular and

visceral work, there remains the altering pressure within the air sacs

of Aves, a force different under states of rest, of running, of deep

water swimming and of flying with or against the wind. Part of the

internal air pressure variation is cared for by the ability a bird has

to respire the air in its sacs and bones, but in prolonged exposure to

the pressure under water or during protracted flight some compensatory

mechanism doubtless exists. This seems to reside in part in the heavy

elastic quality of the arterial stalk and the very rich venous supply of

the abdomen, including the renal-portal system and the distensible

pelvic veins. Just where the governing power for this mechanism resides

is as much a matter of debate as in the case of the human being, but

certain researches would place it in the caudate lobe and pituitary

body.

Having discussed these general comparative data we can now pass to a

consideration of the pathology seen at this Garden. The subject will be

studied from the standpoint of the vessels as a system and the changes

peculiar to it. Naturally the most important lesions affect the great

stalks and the principal trunks, from which the processes may continue

into the smaller vessels. The essential alterations are inflammatory and

degenerative, of which the latter are by all odds the more important.

The former are either involvements of the vessel walls by frankly

infectious processes, or less easily proved to be bacterial in origin,

as is the case with periarteritis nodosa. Acute arteritis and phlebitis

are constantly encountered and present nothing unusual. General nodal

periarteritis has been seen in the lower animals, Lupke having

reported[14] before the German Pathological Society a big outbreak in

cows, but it is less common than among men; we have not discovered it

here.

THROMBOSES.

Thrombosis is practically always a parasitic or an infectious process

although at times considerable difficulty is encountered in explaining

the source of the worms or bacteria. Thus, for example, the iliac or

femoral thromboses which are at the bottom of intermittent claudication,

are frequently quite vague in origin. We have had one such case in a

deer in which a partly occluding thrombangeitis existed in both femoral

arteries and veins. Mesenteric thrombosis, a serious condition in cattle

and horses from infestation with sclerostomum or strongylus, has not

been proven at the Garden, but we have seen one case of numerous

thromboses of the venous radicals in the jejunal wall apparently due to

some nematode larvæ; the specimens were so soft by decomposition that

determination was not attempted. There occurred a thrombosis of the cava

and aorta originating from a necrotizing cloacitis, apparently

streptococcal in nature, in a Demoiselle crane. The clot, while not

totally occlusive, extended nearly as far as the heart in the vein and

the abdominal aorta. There is also on record a thrombosis of the vena

cava and right pulmonary vein in an American beaver, harboring

Hepaticola hepatica in the liver, with a fibrosing pneumonia due to this

parasite. Another case in which parasites seemed to take a hand

concerned a common raccoon with tapeworms (sp.?) in the small intestine

and microscopically discoverable parasitic parts in the lungs; these

organs were the seat of extensive congestion and venous thrombosis, the

latter containing really enormous numbers of diplococci. The parasites

probably paved the way for bacterial invasion. A frank case of septic

thrombotic aortitis was noted in a Rice Grackle, the infectious focus

apparently being a vegetative “tricuspid” valvulitis.

ARTERITIS.

In addition to these cases, productive inflammatory changes were

discovered five times affecting vessels in or near frank inflammatory

processes. The animals affected with this productive process were three

birds, a rodent and an elephant. In the case of two birds and the rodent

the process was associated with chronic intestinal lesions, while in the

elephant it was found as an endarteritis obliterans in large vessels of

the lung of chronic pulmonary tuberculosis occurring in this animal.

These instances serve as examples of the truly productive inflammatory

processes affecting vessels and illustrate the distribution through the

animal kingdom. Pathogenetically there are no essential differences, and

histologically they correspond to the forms seen in man. Had every piece

of tissue been subjected to microscopy wherein such lesions might have

existed, more examples might have been discovered, but these processes

excite no peculiar secondary effects so that attention is not drawn to

them directly. The only noteworthy difference between mammals and birds

is the fragile character of the clots in the latter class. This is

peculiar because the principal response of this class to an infectious

irritant is coagulation necrosis, liquefying enzymes apparently being

absent or small in quantity.

Fatty deposits in the aortic intima are by no means uncommon in the

human subject and are encountered at all ages, even in youth at a time

when progressive arteriosclerosis does not accompany them. There is a

belief in many quarters that this fat may be laid down and then removed.

Such deposits are exceedingly rare in wild animals; when they occur it

is in small indefinite patches and not the bands or rows as found in

man.

TABLE 5.

_Table Showing the Incidence of Degenerative Arterial Disease, the

Percentage in Animals Subjected to

Autopsy and the Principal Associated Pathology._

════════════════╤═════╤══════════╤═════════╤═════════╤══════════

│Total│Percentage│ Due to │Aneurysms│Myocardial

│ │ of order │parasites│ │ disease

│ │ │ │ │

────────────────┼─────┼──────────┼─────────┼─────────┼──────────

Primates[15] │ 3│ .6│ │ │ 3

Carnivora │ 16│ 3.3│ 5│ 7│ 1

Ungulata │ 13│ 3.5│ 2│ │ 1

Marsupialia │ 3│ 1.8│ │ │

Total │ 35│ 1.8│ 7│ 7│ 5

│ │ │ │ │

Passeres │ 3│ .22│ │ 2│

Picariæ │ _2_│ 2.2│ │ │

Psittaci │ 13│ 1.8│ │ 1│

Striges │ 3│ 2.2│ │ │ 1

Accipitres │ 13│ 6.6│ │ 1│ 4

Galli[16] │ 5│ 1.6│ 1│ │ 4

Steganopodes[16]│ _5_│ _25._│ │ │

Herodiones │ 1│ 1.│ │ │

Palamedes │ _1_│ _20._│ │ │ 1

Anseres │ 11│ 3.4│ │ 2│ 4

Struthiones │ _7_│ _22._│ │ │

Alectorides │ _2_│ _5.4_│ │ │ 1

Total │ 66│ 1.8│ 1│ 6│ 15

────────────────┼─────┼──────────┼─────────┼─────────┼──────────

Grand Total │ 101│ 1.8│ 8│ 13│ 20

────────────────┴─────┴──────────┴─────────┴─────────┴──────────

════════════════╤══════════╤═══════╤═════════╤══════════

│Valvulitis│ Renal │ Chronic │ Chronic

│ │disease│pulmonary│infectious

│ │ │ disease │ disease

────────────────┼──────────┼───────┼─────────┼──────────

Primates[15] │ │ │ │ 1

Carnivora │ │ │ 1│ 5

Ungulata │ 1│ 2│ 3│ 2

Marsupialia │ │ │ │

Total │ 1│ 2│ 4│ 8

│ │ │ │

Passeres │ │ │ │

Picariæ │ │ │ │

Psittaci │ │ 6│ 3│ 2

Striges │ 2│ │ │

Accipitres │ 2│ 5│ 2│ 4

Galli[16] │ │ 2│ 1│ 2

Steganopodes[16]│ 1│ 3│ │

Herodiones │ │ │ │

Palamedes │ │ 1│ │

Anseres │ 1│ 4│ 1│

Struthiones │ │ 1│ 2│ 3

Alectorides │ │ 1│ │

Total │ 4│ 25│ 9│ 11

────────────────┼──────────┼───────┼─────────┼──────────

Grand Total │ 5│ 27│ 13│ 19

────────────────┴──────────┴───────┴─────────┴──────────

For meaning of italics see foot note Table 1.

DEGENERATIVE ARTERITIS OR ARTERIOSCLEROSIS.

Whether or not it be exact to speak of the more protracted forms of

vascular disease usually called arteriosclerosis or atheroma as

degenerative, such changes form the most pronounced features of the

lesions, and we have made such a separation at this laboratory. Here is

not the place to engage in the academic discussion of the nature of the

process, but I wish to state that collectively the changes as seen in

such lesions in the lower animals are more degenerative than productive,

and that we have never seen true ulcerative atheroma as it not

uncommonly appears at the autopsy table in any large hospital. This

disease of the vascular walls has long been attributed to alcohol, gout,

syphilis and other such prolonged intoxications to which we might apply

the light term of “toxins of civilizations.” Too little credit, or

discredit has been given to chronic intestinal disorders, overeating,

and overdrinking of ordinary fluids, to entirely incorrect diets, and to

chronic bacterial diseases. Even though the exact counterpart of the

disease in man does not occur in lower animals, we shall see the

probable association with food and with habits, in a manner discordant

with former teaching of the causation of the disease.

The group to which the name degenerative arteritis has been applied is,

as has already been indicated, more productive than the analogues seen

in the human being, but indeed it is questionable whether the lesions

even in the lower animals are not more degenerative than productive.

Since, however, chronic arteritis is always associated with damage to

the elastic and muscular fibres of the media as well as with fatty

change and overgrowth of the intima, all the deforming and degenerative

cases will be classed together.

The general picture in mammals is one of diffuse rather than of plaque-

like thickening, but well outlined raised or depressed areas are

encountered. In the aorta and larger branches one may find irregular

streaking and loss of elasticity with fairly clear, pale yellow or gray,

flat sections of distinct opacity. Rarely these may contain calcareous

matter, a change most often seen in the carnivores. The lesions are very

largely limited to the aorta; 26 or 76 per cent. of the 35 cases had

this distribution alone. The arch seemed never to be affected alone, and

indeed it is rather commoner to find opaque patches stretching along the

thoracic or even abdominal portion; this is especially true of the

Ungulata.

[Illustration:

FIG. 2.—ARTERIOSCLEROSIS AND ATHEROMA. THORACIC AORTA. JACKAL (CANIS

AUREUS). THIS WAS CONTINUED TO THE MESENTERIC AND ILIAC VESSELS.

]

There have been also in mammals five cases of mesial change which have

given rise to the picture described by Mönckeberg and usually entitled

by his name. However, the noteworthy differences between the wild animal

and the human cases are the absence of advanced calcification in the

media under the concavities and the prominence of the changes in the

aorta near the heart to be found in the former. These few cases do not

permit an association of the arterial disease with any particular

pathology in other parts.

Considered minutely, the outstanding lesion in the class Mammalia is the

separation of the elastic fibres by fluid and debris, apparently derived

from the degenerated muscle fibres, associated with a decrease of round

and elliptical nuclei. Globules and hyaline pink staining material are

often collected between split-up elastic strands, which fibres in some

cases seem quite numerous, in others reduced. In the intima heaping-up

of cells and fibres is very moderate in degree while usually one finds

only subendothelial edema. When the process has advanced far, the

microscopy is like that of well developed human lesions. Arterial

degeneration due to parasites gives a different picture in that medial

degeneration is far advanced and some fibrinocellular activity is seen

upon the intima when this tissue remains. When, however, the infestation

has proceeded to weaken the wall sufficient for it to give way into an

aneurysm, little or no vestige of the true arterial wall is left.

In the Aves the distribution and anatomy of this process present some

differences. The aorta is as usual most conspicuously the seat of

change, but it is noteworthy that the dilatation or ampulla immediately

above the aortic valves and from which the main vessels spring, is

practically always free of lesions which are on the other hand most

marked in the thoracic and abdominal sections. One’s attention is

usually attracted to the aortic surface by its roughness although

visibly there may be no plaques, but upon close inspection a mottled

opacity may be detected. This all seems due in the few cases subjected

to tissue section, to hyperplasia of endothelia, with or without fibre

increase. The media may show muscular granularity or no change at all.

At the stage when plaques are formed, fairly well outlined, firm but

rather brittle, raised areas are detected, seated upon a distinctly

opaque gray wall. The remainder of the vessel may be smooth and elastic

but sometimes, in the Accipitres for instance, a general resistance to

pressure and tension is found. Microscopically such a vessel will show a

media the seat of ruptured muscle fibres, split-up or broken elastica

and some debris, while the intima is covered with active and distinct

fibrocellular exudate.

I have for comparison divided the cases into those in which the

superficial productive character was prominent and those seemingly

entirely a degeneration of the media, that is with inactive intima. In

mammals 77 per cent. of the cases were of the degenerative type while in

birds 50 per cent. were of this kind. The exact importance of this

difference is not easy to evaluate, but with the facts that the bird has

a greater elastic supply for its large vessels and a greater wall to

calibre ratio, it is interesting. The aorta alone was affected in half

of the birds, the remainder showing lesions in the carotids and

femorals.

The tendency for the media to degenerate would lay the basis for

concavities on the intimal surfaces after the type seen in Mönckeberg’s

sclerosis. A number of cases of this variety have been encountered, but

instead of being better developed in the vessels of extremities as in

man they have presented more definite pictures in the aorta and

pulmonary vessels. Examples will be quoted under the discussion of the

various orders.

[Illustration:

FIG. 3.—ARTERIOSCLEROSIS, ATHEROMA AND ANEURYSMAL DILATATIONS IN

THORACIC AORTA. WILD CAT (FELIS RUFFUS).

]

Primates are not often affected with degenerative arterial disease, two

of the instances observed showing this change confined to the coronary

vessels. As might be expected the myocardium in both was affected, and

in one animal had a definite concentric hypertrophy. A very interesting

case was encountered in a Lion-tailed Macaque (_Macacus silensis_). His

heart showed distinct fibrosis of the conducting pathways from auricle

to ventricle and of the papillary muscles. No atheroma was present in

the aorta, but in the pulmonary distinct sacculations of the Mönckeberg

type were found. Mesial degeneration was apparently responsible, but no

calcification had occurred. Death was due to acute gastritis.

Carnivora present about half the cases seen in mammals and 16 per cent.

of the total. Five of the sixteen cases owe their origin to parasitic

arteritis and were combined with aneurysms. As will be noted by

consultation of the list there is no outstanding accompanying pathology,

a fact which makes parasites more important. One case of mesial

degeneration, resembling the Mönckeberg type was observed in the

thoracic aorta of a bear.

Ungulata are generously represented, thirteen cases being recorded

distributed rather unevenly between the odd-toed (1 or 8.5 per cent.)

and even-toed groups (12 or 2.9 per cent.). The single case in the first

group occurred in a Zebra (_Equus burchelli_) wherein was found about

the middle of the thoracic aorta a diffuse thickening of media and

intima in a circular plaque approximately two centimetres in diameter;

it was by no means so well developed as similar lesions in the even-toed

ungulates. This recalls the expression of doubt by Zinserling as to the

occurrence in the horse of arteriosclerosis similar to that in human

beings.

The lesions in the Artiodactyla are both in plaques and diffuse, the

aorta and its branches sometimes being quite wrinkled but beset with

firm elevations with and without calcification. These changes are fairly

definite and, although they never attain the development seen in man,

resemble the stage of wrinkling and roughness in the preulcerative stage

of the human analogue. Two of the cases were associated with dilatations

of the mesenteric vessels and with periarteritis, a picture strongly

suggesting parasitic infestation; in one case ineffectual search was

made, in the other no record is made of the parasites. Renal disease

occurred only twice and myocardial damage only once. Chronic pulmonary

disease, present thrice, took the form of tuberculosis twice and pleural

adhesions with atelectasis once.

Marsupialia present three quite interesting cases, a Tasmanian Devil

(_Sarcophilus ursinus_) and two Kangaroos (_Macropus_). The first showed

distinct sacculations in the ascending aorta, suggestive of Mönckeberg’s

sclerosis but equally resembling several small or incomplete aneurysms.

The underlying vessel was opaque and stiff, continuing so to the middle

of the thoracic portion. The other marsupials showed distinct mesial

damage with early calcification and a roughened intima; once the

pulmonary artery was involved.

It will be noticed that the orders Rodentia and Lemures are missing from

those showing arterial disease although we have a reasonable number of

autopsies upon them.

Passeres are hardly good exponents of vascular disease, an interesting

thing in view of their large heart, heavy vessels, and flying habits. It

is, however, striking that two of the three birds of this group had

aneurysms of the aorta, one of which ruptured just above the origin,

partly into and partly outside the pericardium. Despite several

microscopical sections we were unable to find the tiny ends of the

breach and any evidence of parasites. In the other case a vegetative

growth occurred on the intima near the dilatation.

[Illustration:

FIG. 4.—ARTERIOSCLEROSIS IN AORTA. OTTER (LUTRA CANADENSIS). THERE IS

RELATIVELY LITTLE INTIMAL CHANGE, THE MEDIA BEING FIBROTIC AND

ALLOWING THE INTIMA TO BE DEPRESSED IN SMALL CONCAVITIES.

]

The Picariæ were represented by a Hornbill and a Toucan. The former

presented roughened yellowish elevations for two centimetres above the

aortic valve; this seemed the only involvement. The Toucan had a few

small scattered but deep yellow plaques in the same location.

Psittaci, although failing to be accredited with a high percentage of

arterial disease, nevertheless present some striking and interesting

changes. In the first place, the central vessels are not so

conspicuously the principal seat of atheroma as is the case in many

other orders, and the lesions are not so productive. It is usual to find

flat areas of opacity, perceptible as easily by section through the wall

as by holding up the opened vessel to the light, the seat of the density

being in the media. This can be followed into the wing arteries and,

upon microscopic section, these smaller vessels will show mesial

degeneration, thus being comparable to arteriocapillary fibrosis of man.

However frequent this picture may be, there are also instances of

overgrowth in the intima, prominences over opacities or raised plaques

at the points of branching, lesions which correspond to the activity of

the inner coat. It is interesting that renal disease, chronic pulmonary

and general infections occur in a goodly proportion of these birds.

Striges is an order of little importance. The lesions in the two cases

consisted of rather prominent plaques in aorta and large branches.

Accipitres stand out as giving the greatest percentage of any order of

which we have had a fair number upon which to make comparisons. Their

arterial lesions are frequently accompanied by renal, myocardial and

valvular disease. Mesial and intimal alterations are about equal in

degree, irregular patches going on to softening without ulceration, and

early calcification being quite prominent. The sickle at the branching

of the renals is a favorite site of deposit. Like the parrots their

arterial damage is not confined to the aorta, but may be found in the

carotids, femorals or small wing arteries. The most common situation is,

however, in the lower thoracic and renal regions.

Galli, represented by five specimens, seem to have their vascular

disease accompanied very often by myocardial and infectious disease.

Their arterial pathology consists of raised gray patches in the aorta

only.

Steganopodes give the highest percentage among avian orders, but this

must be held _sub judice_ because of the small number of specimens

subjected to autopsy. Renal disease occurred in three cases. Their

lesions are in the form of yellow opaque streakings in the aorta and its

branches, in one case following the carotid half way up the neck.

Plaques are not common, and when they occur are streaky and illy

outlined.

Herodiones, represented only by a heron, are negligible. This bird

showed a diffuse thickening with early thrombotic deposits attached to

the intima.

Palamedes are represented by a Screamer which showed around the orifices

of the renal arteries an early fatty deposit and mesial opacity.

Anseres present a considerable number of cases which are accompanied by

cardiac, renal and general pathology. The character of the lesions is

like that of the Accipitres and the distribution differs in only one

particular. In four of these eleven cases the elevations or opaque areas

were limited entirely to the stretch of aorta which might be compared to

the arch in mammalia, that is the part with which the right subclavian

is in closest contact and which bends almost directly backward to become

the thoracic aorta. This excludes the ampulla just above the aortic

valves. There seems no real reason for this and it may be accidental.

[Illustration:

FIG. 5.—AORTIC ARTERIOSCLEROSIS. SARUS CRANE (GRUS ANTIGONE). THE

LESIONS ARE ELEVATED AND IRREGULAR.

]

Struthiones, with seven specimens having arterial disease in the great

vessels alone, seem to have no especial characters unless these be in

the heavy furrowing and stiffness of the wall, with opaque, elevated,

indefinite patches, seen mostly in the descending aorta; once a long

tough and partly brittle stretch was found in the carotid.

Alectorides, with a relatively high percentage, present irregularly

outlined fatty and finely granular patches in the intima of the lower

aorta and abdominal vessels, and, in two cases, as far as the vessels of

the lower extremities could be followed.

The orders Columbæ and Fulicariæ are missing from the list of Aves

having arterial disease, yet a reasonable number of autopsy records are

at hand.

SUMMARY ON ARTERIOSCLEROSIS.

Having discussed the orders separately, a review of the whole situation

is desirable. Chronic arteritis, or as it is usually called

arteriosclerosis, is common to very many zoological orders, and its

principal lesions are comparable throughout the two classes under

consideration. A statement as to its incidence would best be made by

adopting an arbitrary number of observations as the desired minimum upon

which to draw conclusions, and I shall adopt one hundred as such a

figure. Accepting this as reasonable, a review of the table indicates

that the order of percentage incidence is: Accipitres 6.6, Ungulata 3.5,

Anseres 3.4, Carnivora 3.3, Striges 2.2, Psittaci 1.8, Marsupialia 1.8,

Galli 1.6, Primates 0.6, Passeres 0.22; the other orders have less than

one hundred specimens each. There is no doubt that carnivorous birds

have the highest incidence of chronic arterial disease. Next in order

come three varieties with nearly equal incidence, the ungulates,

anserine birds and carnivorous mammals. These orders have little in

common unless it be that in nature they are often engaged in prolonged

or strenuous effort, as in fight or flight. We possess no measurement of

their vascular supply but by consultation of the table giving heart

weights (page 63) it will be found that three of them have values below

that of the class in which they belong; the Carnivora alone have a

greater heart-to-body ratio than the average for its class Mammalia. Nor

do these orders have any direct dietetic relationship. The expected

longevity of these groups does not permit one to discover any reason for

arterial changes except perhaps that they have a reasonably good

viability under park conditions, and therefore many have a longer

opportunity to develop vascular disease. It so happens, however, that

the first four groups are the most likely to suffer from

gastrointestinal inflammation, of dietetic or bacterial origin.

It is interesting, but not easily explicable that the orders of great

activity, Primates and Passeres, are at the end of the list; their food

is very largely carbohydrate in character. Just why Lemures, Rodentia

and Columbæ should be missing is not quite clear, because orders of

comparative habits and food are included.

A review of the concomitant pathology reveals the fact that nephritis

more often accompanies these processes than any other single condition.

Among the chronic infectious disease in the table is included chronic

enteritis; this group falls well behind the renal diseases. The

relatively small number of cases of valvulitis speaks rather against an

active infectious origin of the vascular lesions.

ANEURYSMS.

Aneurysms have been observed all over the world and in nearly all the

larger orders. The London Garden has had an unusually large number to

report, the most striking being that described by Seligman in the 1906

Report of the Society, in a tiger thirteen years in captivity which had

fourteen sacculations from pea to plum size scattered along the aorta.

Even with the number of cases on record and those collected here it

would be unwise to draw deductions as to their incidence or as to the

possibilities of vascular dilatation in any given order. Horses have

aneurysms occasionally, cows and dogs rarely, according to Rievel. I

can, however, state that there has not occurred in our experience a

large growing pulsating aneurysm in the aortic arch region comparable to

the condition so well known in man. The literature to which we have had

access gives a definite impression that parasitism of vessel walls is

the most important factor in the causation of ectasia, and that simple

non-parasitic arteriosclerosis is relatively unimportant. Two of our

seven cases seem to have been free of parasites but the notes cannot

entirely assure one of this. The distribution of cases at this Garden is

found in Table 5.

[Illustration:

FIG. 6.—PARASITIC ANEURYSM IN THORACIC AORTA. PARADOXURE (PARADOXURUS

LEUCOMYSTAX). PARTLY SACCULAR, PARTLY DISSECTING ANEURYSM WITH OPEN

THROMBOSIS AS INDICATED BY THE GLASS ROD. PIECES OF WORM FOUND IN

WALL. COULD NOT OBTAIN WHOLE SPECIMEN, SPECIES UNDETERMINED.

]

A dilatation of the first part of the arch in a seal to a size which

might be described as an aneurysm caused us to make such a diagnosis,

correctly enough from the size and shape of the vessel but possibly

worthy of reconsideration in light of the fact that no damage to the

wall was found. At the heart and in the descending arch the diameter

measured 4–5 cm., while the first part of the aorta measured 7.5 cm.

This great irregularity in width could not be found in other seals

albeit this section of the arch is usually a trifle larger than its

origin and descending portion. The cava in seals is also large, but in

this particular animal it measured 6 cm. across at the liver where there

is a normal dilatation. These two spaces are looked upon as normal

reservoirs for blood during diving, but the case in question seemed to

have excessive “aneurysmoid” enlargements without mural disease. London

reports an aneurysm of the aorta in a seal.[17]

Aneurysms are not so common in birds, the incidence being in comparison

with mammals as 1 to 2.2. Two seats are prominent for their development:

the sinuses above the aortic valves and the first part of the subclavian

vessels; two of the six cases occupied the first position, two the

second, while one other lay in the arch of the aorta, the last in its

descending thoracic portion. Those developing over the valves seem to

arise from simple degenerative arteritis; those that occupy the other

locations are apt to be surrounded by plaques on the intima. Aneurysms

in birds reveal by microscopy some trace of all the vascular coats and

seem not to construct an adventitia from surrounding areolar tissue. The

veins have presented no peculiar pathology, except in tumors which will

be taken up later. A Derby’s Tyran showed a phlebitis and periphlebitis

of the left subclavian vein, of mycotic nature, which led to death by

rupture and hemorrhage.

SECTION IV

DISEASES OF THE BLOOD AND BONE MARROW

The production and physiology of the circulating blood seem closely

similar in the two classes under consideration, although the anatomy is

not the same in birds and mammals, variations also occurring within the

latter group. Pathological responses follow comparable lines in that

hemolyzing agencies, be they hemosporidia, absorptions from metazoan

parasites or bacterial toxins, produce a reaction in erythropoietic

centres, and positively chemotactic viruses call forth increases in the

colorless elements. We have also observed a decrease of leucocytes in an

Orang Utan suffering from influenza, a finding analogous to that in the

human attack. There is, however, a much less ready response on the part

of birds to any leucocyte-stimulating influence, in this class the

mononuclears seeming to bear much of the burden assumed by the myeloid

cells of Mammalia or at least appearing on the stage very quickly so

that any increase of the latter is overshadowed by them. Perhaps this

apparent difference may be further explained by the greater number of

colorless blood cells, structures which might be called the principal

secondary defences of the body and constantly at the disposal of the

organism, normally present in the birds’ blood; they amount to 25,000

per cubic millimetre in birds, while in the mammals very few varieties

have half this number. On the accompanying Table (6) will be found a few

differential leucocyte counts now known to us.

TABLE 6. _Differential Percentages of Leucocytes._

_The Figures are based upon Counts of Two Hundred Cells upon Two Slides unless

Otherwise Specified. Blood Films were taken from Apparently Healthy Animals in the

Exhibition Cages._

════════════════╤════════════╤═══════╤═══════╤═══════╤══════════╤══════════════════

Animal │ Polymor- │ Small │ Large │Eosino-│ Special │ Notes

│phonuclears.│Lympho-│Mononu-│philes.│ │

│ Per cent. │cytes. │clears.│ Per │ │

│ │ Per │ Per │ cent. │ │

│ │ cent. │ cent. │ │ │

────────────────┼────────────┼───────┼───────┼───────┼──────────┼──────────────────

Potto │ 20.│ 67.│ 7.1│ 5.9│ │

Perodicticus │ │ │ │ │ │

potto │ │ │ │ │ │

Rhesus Macaque │ 30.2│ 61.4│ 5.6│ 2.8│ │

Macacus │ │ │ │ │ │

rhesus. │ │ │ │ │ │

│ (Av. 5 counts) │ │ │ │

Raccoon-like Dog│ 62.2│ 32.│ 2.│ 3.8│ │

Canis │ │ │ │ │ │

procyonoides. │ │ │ │ │ │

Swift Fox Canis│ 65.│ 18.│ 13.│ 1.│ 3 per │

velox. │ │ │ │ │cent. Baso│

Dingo Canis │ 77.│ 15.4│ 3.8│ 3.8│ │

dingo. │ │ │ │ │ │

Timber Wolf │ 76.5│ 15.5│ 3.5│ 4.5│ │

Canis │ │ │ │ │ │

mexicanus. │ │ │ │ │ │

Wild Cat Felis │ 55.8│ 34.│ 7.│ 3.8│ │

ruffus. │ │ │ │ │ │

Gray Ichneumon │ 52.6│ 44.4│ 2.3│ .7│ │

Herpestes │ │ │ │ │ │

mungo. │ │ │ │ │ │

Indian │ 66.│ 20.│ 14.│ 0.│ │

Paradoxure │ │ │ │ │ │

Paradoxurus │ │ │ │ │ │

niger. │ │ │ │ │ │

Large spotted │ 60.│ 31.2│ 1.2│ 7.6│ │

Civet Viverra │ │ │ │ │ │

megaspila. │ │ │ │ │ │

Ocelot Felis │ 79.│ 15.6│ 3.5│ 1.9│ │

pardalis. │ │ │ │ │ │

Texas Skunk │ 44.1│ 46.3│ 4.3│ 5.3│ │_a._ There are

Mephitis │ │ │ │ │ │several grades of

mesomelas. │ │ │ │ │ │eosinophilic

│ │ │ │ │ │granulations,

│ │ │ │ │ │ranging from very

│ │ │ │ │ │fine to very

│ │ │ │ │ │coarse. They are

│ │ │ │ │ │entirely discrete,

│ │ │ │ │ │however, and the

│ │ │ │ │ │eosinophile cells

│ │ │ │ │ │are quite distinct

│ │ │ │ │ │from the

│ │ │ │ │ │homogeneous

│ │ │ │ │ │neutrophiles.

Tayra Felis │ 75.6│ 19.2│ 4.1│ 1.1│ │

tayra. │ │ │ │ │ │

White nosed │ 60.│ 20.│ 18.│ 2.│ │_b._ The

Coati Nasua │ │ │ │ │ │protoplasm of the

narica. │ │ │ │ │ │leucocytes shows

│ │ │ │ │ │practically no

│ │ │ │ │ │stain. Mitotic

│ │ │ │ │ │figures are

│ │ │ │ │ │frequent among the

│ │ │ │ │ │polymorphonuclear

│ │ │ │ │ │cells. The small

│ │ │ │ │ │lymphocytes show

│ │ │ │ │ │basophilic

│ │ │ │ │ │granules.

Crab eating │ 45.│ 42.│ 2.5│ 10.5│ │

Raccoon. │ │ │ │ │ │

Procyon │ │ │ │ │ │

cancrivorous. │ │ │ │ │ │

Ring tailed │ 39.2│ 54.7│ 4.3│ 1.8│ │

Bassaris │ │ │ │ │ │

Bassariscus │ │ │ │ │ │

astutus. │ │ │ │ │ │

Kinkajou Potos │ 47.4│ 42.5│ 6.│ 4.1│ │

caudivolvulus.│ │ │ │ │ │

Common Raccoon │ 46.│ 42.9│ 7.4│ 3.7│ │

Procyon lotor.│ │ │ │ │ │

Texas White │ 67.│ 19.│ 11.│ 3.│ │

footed Mouse │ │ │ │ │ │

Peromyscus │ │ │ │ │ │

leucopus. │ │ │ │ │ │

Kangaroo Rat │ 55.│ 33.│ 6.│ │ 5 per │_c._ Many

Perodipus │ │ │ │ │ cent. x │leucocytes were

richardsoni. │ │ │ │ │ cells. │noted, with deeply

│ │ │ │ │ │staining nuclei

│ │ │ │ │ │filling up most of

│ │ │ │ │ │the cells. The

│ │ │ │ │ │protoplasm was

│ │ │ │ │ │colored a deep

│ │ │ │ │ │brown. These were

│ │ │ │ │ │called x cells

│ │ │ │ │ │pending

│ │ │ │ │ │investigation.

Polecat Mustela │ 42.4│ 54.6│ 2.1│ .9│ │

putorius. │ │ │ │ │ │

Common Opossum │ 44.│ 39.│ 7.│ 9.│ 1 per │_d._ Polynuclears

Didelphys │ │ │ │ │cent. Mast│quite large, with

virginiana. │ │ │ │ │ cells. │deeply staining

│ │ │ │ │ │nuclei which are

│ │ │ │ │ │in many instances

│ │ │ │ │ │entirely separate

│ │ │ │ │ │and distinct.

Bridled Wallaby │ 58.3│ 38.8│ 2.│ 4.2│ │

Onychogalea │ │ │ │ │ │

frenata. │ │ │ │ │ │

Six banded │ 57.1│ 23.2│ 6.3│ 13.4│ │

Armadillo │ │ │ │ │ │

Dasypus │ │ │ │ │ │

sexcinctus │ │ │ │ │ │

Elephant Elephas│ 15.│ 47.4│ 7.6│ 5.8│ (Bilobed │_e._ The ordinary

indicus. │ │ │ │ │ 23.8) │polymorphonuclears

│ │ │ │ │(Basophile│are very few in

│ │ │ │ │ .4) │number, and those

│ │ │ │ │ │seen have nearly

│ │ │ │ │ │all a faint

│ │ │ │ │ │acidophilic or

│ │ │ │ │ │basophilic

│ │ │ │ │ │character. The

│ │ │ │ │ │eosinophiles are

│ │ │ │ │ │quite distinct and

│ │ │ │ │ │their granulations

│ │ │ │ │ │are large and

│ │ │ │ │ │globular. The

│ │ │ │ │ │cells called

│ │ │ │ │ │bilobed are

│ │ │ │ │ │unusual and can

│ │ │ │ │ │probably best be

│ │ │ │ │ │accounted for as

│ │ │ │ │ │directly dividing

│ │ │ │ │ │small lymphocytes.

│ │ │ │ │ │The staining

│ │ │ │ │ │properties and

│ │ │ │ │ │shape of the

│ │ │ │ │ │nuclei of the

│ │ │ │ │ │bilobed cells are

│ │ │ │ │ │most closely

│ │ │ │ │ │related to the

│ │ │ │ │ │lymphocytes. They

│ │ │ │ │ │are not always

│ │ │ │ │ │regular, however,

│ │ │ │ │ │but may be almost

│ │ │ │ │ │as irregular as

│ │ │ │ │ │the polynuclears.

│ │ │ │ │ │In practically

│ │ │ │ │ │every instance,

│ │ │ │ │ │however, a

│ │ │ │ │ │connecting isthmus

│ │ │ │ │ │may be found

│ │ │ │ │ │between the

│ │ │ │ │ │spherical nuclear

│ │ │ │ │ │portions. No

│ │ │ │ │ │mitotic figures

│ │ │ │ │ │seen. The

│ │ │ │ │ │protoplasm is

│ │ │ │ │ │homogeneous and

│ │ │ │ │ │pale blue or lilac

│ │ │ │ │ │in relatively

│ │ │ │ │ │large amount. No

│ │ │ │ │ │granules were ever

│ │ │ │ │ │seen.

────────────────┴────────────┴───────┴───────┴───────┴──────────┴──────────────────

It would seem, from a general observation of simple and infected wounds

and from a few blood counts, that the response of leucocytes in the

lower animals is greater than in monkeys and man. The ease with which

animals endure a wound and the rapid local pus formation about an

infection speak for an easy mobilization of their cellular defenders;

their connective tissue elements seem equally well brought into play. In

so far as birds are concerned perhaps the normally large number of

leucocytes and the participation of local tissue cells in response to

irritation is a preparatory protective mechanism because of their

relatively small amount of bone marrow which may not be able to mobilize

new cells rapidly; many of the birds, notably those prepared for long

flight, have much of their osseous system given over to air space. The

number of red blood cells is also greater in Mammalia, which show a

variation from 4,000,000 per cubic millimetre in some small genera to

12,000,000 per cubic millimetre in some ungulates, while birds vary from

2–5,000,000 per cubic millimetre. Despite these fundamental differences

in the classes, pathological changes of anemia, leucocytosis and

leucemia are comparable; polycythemia in lower animals is unknown to me

but may of course occur.

ANEMIA.

As in human pathology this condition may be divided into the group that

follows some disease which damages the red blood cells or their source,

called secondary, and those cases not preceded by such a condition,

called primary. Formerly this latter group, known as progressive

pernicious anemia, was copiously represented, but study has discovered

that worms, inorganic poisons and infections can produce a picture of

grave anemia so that the formerly large group has dwindled. We now

conceive a primary anemia to be one without discoverable responsible

antecedent pathology, therefore a disease of the bone marrow itself.

There is one variety, hemolytic anemia, which seems to be an

intoxication of the bone marrow with solution of red cells, but the

affected tissue puts up some struggle against the poison. In another

primary, the so-called aplastic anemia, no activity at all is shown by

the marrow, no young cells appearing in the circulation. Clorosis, or

green sickness of young persons, is a primary anemia and presents itself

as a moderate cell reduction with a disproportionately low hemoglobin

percentage. As a disease entity this does not occur in the lower

animals, so far as I am aware, but a very few hemoglobin estimations and

a reference to the literature would indicate that well marked hemoglobin

anemia does occur.

In so far as the pathology of anemia is concerned we are obliged usually

to judge by the appearance of the blood and tissues, the yellowish

pallor of the mucous membranes, the condition of the marrow and the

amount of pigment; severe rapid cases show hemorrhages and prolonged

cases have fatty degeneration of the parenchymatous organs. For a

decision of the primary or secondary nature we must judge the

accompanying pathology and the condition of the bone marrow.

SECONDARY ANEMIA.

Secondary anemia can be laid in general to insanitary housing or

inappropriate diet over a long period, to chronic bacterial infection of

low grade, to the action of blood parasites or those of the bowel which

either suck blood or elaborate an absorbable toxin, or to single great

or repeated small hemorrhages. We shall now consider the cases at the

Garden. Perhaps many other animals have had a substandard blood, but

these are the cases in which the gross appearance attracted close

scrutiny in this direction. London has had much anemia, probably from

their reported heavy infestation with parasites, but this factor has

with us apparently played a small rôle in the production of anemia.

IN MAMMALIA.

In so far as the Primates are concerned the one outstanding cause of

anemia is degenerative disease of the osseous system. In both rickets

and osteomalacia there is an irregular hyperplasia of the marrow, which

is usually more marked in the latter. In osteomalacia one finds

irregular areas of congestion or even hemorrhage besides masses of a

gelatinous fatty tissue while scattered about are pink spots where the

marrow is better preserved. In rickets, on the other hand, the tissue is

more uniformly congested and less sharply separated from the endosteal

osseoid material or the irregular epiphyseal spongiosa. The fibroid or

osteoid growth of osteomalacia seems to be fairly well differentiated

from the marrow tissue although it may send strands into the canal and

across the spongy area. Histologically there is not a distinct

difference in the appearances nor do they differ from the human

analogue. In those cases which develop late in life the red cell centres

are very few in number but usually active. In the blood, one finds a few

nucleated and stippled cells, but not much change in size and shape of

the erythrocytes.

It does not seem that the anemia can be the cause of death, for among

our thirty-nine cases of osteomalacia and rickets, the prosectors have

thought it of sufficient importance to record in the diagnoses but

eleven times. There are usually complications of pneumonitis or

enteritis to finish the animal before the poverty of the blood will do

so, and our records show only a Black Spider Monkey (_Ateles ater_), a

Silky Marmoset (_Leontocebus rosalia_) and a macaque (sp.?) with

osteomalacia and grave secondary anemia. It would seem, however, that

hemoglobin anemia must exist, for, despite one record of 40 per cent.,

Fleischl, no excess of pigment deposit is noted in the spleen, liver or

marrow.

Carnivora have shown a moderate number of diseases of the skeleton but

the occurrence of a marrow involvement seems less frank, although the

anatomical changes are similar. However, there are three grave secondary

anemias recorded in eleven carnivores suffering from osteomalacia and

rickets. Another prime cause of low blood value in this order is

gastrointestinal inflammation; in seventeen cases of anemia, of

secondary nature, five showed gastroenteritis of severe grade or

protracted character. Perhaps the most prolific single cause of this

blood change is parasitism, six of the seventeen cases showing

infestation, five of which are nematodes and two cestodes, one showing

both. The details of these are worth recording. Two young Jungle Kittens

(_Felis chaus_) from the same litter died of enteritis with a noticeable

anemia; they harbored in their upper small intestine ascarids, and one

of them had a few hookworms (sp.?). A Kinkajou (_Potos caudivolvulvus_)

died from a general mild infection, emanating from a pneumonia perhaps,

and showed a heavy infestation with tænia (sp.?). An American Wild Cat

(_Felis ruffus_) died from acute catarrhal enteritis and anemia; the

parasitological findings included Filaria fasciata, adults in abdominal

and gluteal muscles, larvæ in the blood; Dibothriocephalis felis,

Ascaris mystax and Uncinaria canina in the small intestines. While the

blood was thin and pale and some pigmentation existed, the condition

could not be called a picture of grave anemia. A noteworthy finding was

the deep pigmentation of almost the entire intestinal wall. Ascaris

mystax was found in an under-sized inbred gray wolf, killed because of

poor coat; there was a marked anemia and atrophy of the skin. An Ocelot

(_Felis chibigonazon_) gave a picture of anemia due to uncinariasis, but

is not so instructive as the following. A Swift Fox (_Canis velox_)

exhibited clearly a case of progressive secondary anemia from uncinaria,

and the history is worthy of a brief recital.

Muscles atrophic, greenish black over abdomen. Fat absent. Lung is

blotched by darker red markings where parenchyma contains distinct

excess of frothy pink watery fluid. No fluid or adhesions in

pericardium. Heart is contracted, and muscle is pale yellow and firm.

The only abnormality consists of slight yellowing of musculature. The

abdomen shows great omentum firmly adherent to fundus of bladder. No

fluid or other adhesions in abdomen. The liver is normal in size,

smooth in surface and has sharp edges, is friable and bright orange

yellow. The section surface is glistening, smooth and dry. Organ is

poor in blood content, greasy and breaks easily. Bladder is large,

contents fluid green bile; duct patulous. Spleen normal. Kidney is

small and smooth, diminished in bulk, normal location, smooth surface,

and pale yellowish gray, consistency, soft, flabby. Ureters normal.

Mouth and teeth normal. Stomach contains scanty brown fluid. Duodenum—

Mucosa bile-stained, contained a solitary nematode worm. In its lower

portion it becomes filled with a blackish red fluid, and its mucosa

becomes studded by heavily outlined punctate hemorrhages whose

positions are best seen through serosa. Jejunum similar in condition

to duodenum and contains four small nematode worms. At one point,

i.e., where the worm is located at beginning of ileum the blood

staining of mucosa is strictly in neighborhood of the worm.

Capillaries nowhere congested. Ileum contains slight amount of

brownish black material, mucosa normal. Large intestine and rectum

normal. Pancreas normal. Lymphatics normal. This is a case of death by

anemia as result of bites of hookworms. There were certainly more than

four worms present antemortem since no males were found, and this may

be explained by a possible diarrhœa which has flushed them out. This

idea is borne out by empty condition of gastrointestinal tract. Animal

Parasites—Uncinaria canina. The four small nematode worms above

mentioned conform in all respects to the given anatomical points of

uncinaria. All four specimens are perfectly formed females. The

location of the hooks was easily determined and established as being

in the most dorsal portion of buccal cavity, and as projecting forward

and ventrally in two groups of three each in same manner as described

heretofore in similar infestations in foxes. The large nematode worm

found in duodenum is, from its possession of three lips and its

general form, an ascaris. The mustache, however, which is so commonly

seen in ascaris worms from this region is absent. Postmortem blood of

heart shows red cells granulated and almost worthless for histological

study. Nucleated reds, however, are absent but other points valuable

in settling the question of anemia cannot be determined.

Lung.—There are no abnormalities in supporting tissue. Alveolar walls

are markedly congested. Bronchi normal and show no trace of larval

hookworm infestation. Air sacs contain many red blood cells together

with a few heart-failure-cells. Congestion of lung.

Liver.—No excess of fibrous tissue. Finer details of structure cannot

be made out owing to advanced autolytic changes. The only possible

pathological changes consist of localized areas where liver cells have

fused to form notable masses of pink granular material suggesting

local necroses. Autolysis.

Intestines.—Four sections are present and all show essentially the

same character of changes. Interstitial tissue between muscular tissue

and submucosa loosely arranged as though separated by edema.

On luminal side of muscular mucosa is a distinct zone of striking

tawny yellow color with hematoxylon-eosin combination. This zone is

smooth homogeneous and contains a few spindle and stellate cells with

no capillaries and with little or no fibrillation. It abuts upon the

fundi of the crypts. Interstitial tissue of mucosa is loose and

infiltrated with round and spindle cells in its deeper portions. Here

it is also congested but congestion is most marked toward lumen where

masses of free blood cells occur in interstitial tissue, within lumina

of crypts and within lumen of intestine itself; no parasites or ova

are found. Epithelium of crypts has granular cytoplasm; goblet cell

formation frequently seen; cilia well preserved. Edema; Subacute

catarrhal enteritis Hemorrhage.

Six instances of nephritis, four parenchymatous and two diffuse, are

recorded in the total of seventeen cases of secondary anemia in

carnivores. Except in the skeletal disease the marrow is very mildly

affected, some edema and reddening grossly and moderate hyperplasia

minutely, being the only noteworthy changes.

The next order is that of the Ungulata wherein we have found but two

cases of frank anemia, an Isabelline Gazelle (_Gazella isabella_) and an

Aoudad (_Ovis tragelaphus_). The former had several lesions of different

etiology and nature so that an impoverishment of the blood is not

astonishing: parasitic (?) cyst in lung, chronic infective arthritis,

calcareous tuberculosis, congestion and edema of lungs, osteomalacia,

and osteofibroma of maxilla. The condition of the aoudad was too

indefinite to permit conclusions.

The marsupials are represented by two common Opossums (_Didelphys

virginiana_) and a Rufous Rat Kangaroo (_Aepyprymnus rufescens_), two of

which suffered also from rickets. The condition of the bone marrow was

unfortunately not recorded, but in other rachitic marsupials this tissue

follows the changes seen in other orders. One opossum had a hypertrophic

gastritis with numerous Physaloptera turgida, a worm frequently

associated with chronic thickening of the mucosa; there was also an

early portal hepatic cirrhosis with enlargement of the spleen.

Among the Rodentia we have had anemias in a Beechy’s Gopher (_Citellus

grammurus beecheyi_) and a Southern (_Sciurus niger niger_) and Western

Fox Squirrel (_Sciurus rufiventer_). The first had a myeloma also, and

will be discussed later. One of the squirrels had osteomalacia, while

the other suffered with diarrhœa and showed hydropic degeneration of the

kidneys, conditions probably due to acute intoxication.

IN AVES.

The class Aves is represented by the orders Passeres, Psittaci, Columbæ,

Herodiones, Gaviæ, Picariæ, Striges, Galli and Accipitres; the first

four are well represented, but in the other orders only one or two cases

have occurred. The causes of anemia in birds are essentially those

discussed for mammals with the provision that greater attention must be

paid to parasites, particularly those of the blood. Several slightly

varying protozoa inhabit the blood corpuscles of birds, and numerous

embryos may circulate after they escape from a parent lying in some

organ or tissue. The rôle of blood parasites, intra- or

extracorpuscular, in the cause of death or of anemia is, however,

somewhat paradoxical. Plimmer seems to credit a heavy infestation with

great value in the cause of death. In the human being an infestation of

one cell in a hundred is a fair grade of malaria; such a relation is

apparently common in birds, and we have repeatedly seen a much heavier

seeding while Plimmer reports as many as 70 per cent. of the

erythrocytes to be carriers of hemogregarines (he has seen 92 per cent.

in reptiles). Can then the effect upon hemic function and vital

resistance be great? It has been our practice to interpret the finding

of circulating protozoa or of larval metazoa as merely reducing the

resistance of the birds so that they succumb more readily to incorrect

food, strange environment or infection.

It is perhaps well to show the state of our records in the Passeres by a

table.

Passeres—Secondary anemia associated with intestinal or visceral

parasites 11

blood parasites 9

intestinal inflammation 6

skeletal diseases and chronic infection (osseous) 3

nephritis 4

miscellaneous and unassociated anemias 8

(entries in this line not included under any

other heading)

Total cases 37

In the first group, two of the birds showed cestodes, one a tænia, the

other not examined for identification; three showed coiled filaria in

the air sacs, two, tropidocerca in the proventricular wall and five had

coiled filaria in the serosa of the stomach. The second group was

infested five times with Halteridium and five times with embryo filariæ.

Anemia was associated with gastrointestinal inflammation alone only

once, the remaining five cases having other finding of greater

significance. The three birds of the next group concerned one with

tuberculosis, one with mycosis and one with a long continued abscess. It

seemed worthwhile to separate four cases of anemia in which nephritis

was a prominent association, in three indeed being the only other

diagnosis. While it is impossible to state that either is dependent upon

the other, and they may of course be coincidental, it is nevertheless

noteworthy that such an obscure relation occurs here as well as in human

pathology. In one of these birds seen recently there was in all

probability a distinct hemoglobin anemia suggested by jaundice, pallor

of the tissues, absence of pigmentations and the finding of large pale

erythrocytes in the heart blood. The last group is a mixed one including

some birds in which only anemia was diagnosed, others with prolonged

hemorrhages, two tumors, intestinal sand, congestion of the lungs and

the like.

The parrots and their relatives are represented by nine specimens, among

which two had proventricular spiroptera, two had long standing

tuberculosis and two had osteomalacia. The notes of the other three are

not sufficient to warrant deductions.

Herodiones showed eight cases of anemia, five herons, one bittern and

two storks. Parasites are noted in only three examples, herons, and it

is noteworthy that these all had flukes in the proventricle or

intestine; one also had ascarids in the proventricle. Two of this order

suffered with long standing inflammation following bone injuries.

Perhaps the outstanding features of this order are the erythrocytic

picture and the condition of the spleen. The red blood cells seem very

fragile or soft, for one often encounters in their fresh or stained

preparation vacuoles or rifts in the protoplasm surrounding the nucleus.

At first we thought these were hemosporidia, but repeated attempts at

their coloration and the absence of pigment granules seem to warrant an

assumption that they are artefacts. In five of the seven instances there

is very definite evidence of present or past activity of the spleen. We

have not always considered it sufficiently prominent to call it a

splenitis, but follicular activity is commonly discoverable, and two

cases of definite fibrosis are recorded. The sun bittern (_Eurypyga

helias_) showed a chronic interstitial nephritis in the atrophic stage.

No other of the wading birds showed secondary anemia. There are seven

cases among the pigeons (Columbæ) where anemic tissues attracted our

attention. Three were associated with osteomalacia, in one of which the

marrow picture was that of an aplastic form being everywhere pale and

flabby without cells under the microscope; it is further interesting in

this case that there was a distinct but ineffectual attempt at bony

regeneration by the periosteum. In another case, this time brought to

death by an enteritis and cloudy swelling of the viscera, the marrow was

hyperplastic and red, there being activity in the basic staining areas

of the head and in the shafts. (Notes of the third case scanty.) None of

the seven cases seems to have been associated with animal parasitism;

one had tuberculosis. The other cases are obscure and not definitely

connected with other pathology.

Ten more cases of anemia were scattered among seven orders. There is

nothing striking or even individual about them worthy of special

mention.

SUMMARY OF SECONDARY ANEMIA.

A review of our records shows that among 5365 animal autopsies we have

recorded anemia of probable secondary character in 122 instances, 53

(2.8 per cent.) mammals and 69 (1.9 per cent.) birds. The orders

represented, with the percentage for the order, are Primates, 25 or 5

per cent.; Carnivora, 18 or 3.7 per cent.; Ungulata, 3 or .8 per cent.;

Marsupialia, 4 or 2.2 per cent.; Rodentia, 3 or 1.5 per cent.; Passeres,

37 or 2.7 per cent.; Psittaci, 9 or 1.3 per cent.; Herodiones, 8 or 8.

per cent.; Columbæ, 7 or 4.7 per cent.; Picariæ, 2 or 2.3 per cent.;

Striges, Galli, Gaviæ and Accipitres, each one case. A consideration of

their associated pathology reveals the fact that four changes are

prominently associated with secondary anemia, to wit: gastrointestinal

inflammation, 26 times (15 mammals and 11 birds); parasitism, 29 times

(7 mammals and 22 birds); osteomalacia, 24 times (18 mammals and 6

birds), and nephritis, 18 times (12 mammals and 6 birds); a few of these

cases overlap, but this is rather the exception than the rule, and this

does not militate against the importance of the connection with anemia.

It will be noted that practically all the important orders of animals

are represented, including species from all over the globe. There is,

however, no especial relation of anemia to the kind of diet or digestive

tract. Conclusions as to the meaning of these figures of incidence are

hardly justifiable. In so far as the blood picture is concerned we can

only record the qualitative appearance and the effect upon tissues. It

cannot be stated that to external observation a secondary anemia

presents any distinguishing features that a specimen in poor condition

may not exhibit. The monkeys formerly dying of tuberculosis had not

infrequently pale buccal mucosa and skin around the eyes, but upon

examination of their viscera, blood or marrow the quality of their blood

could not be called greatly substandard. Slide smears of secondary

anemia in many specimens would occasionally show stippling or a moderate

number of nucleated cells with anisocytosis and poikilocytosis. This is

much more frankly exhibited in the Aves, wherein displaced karyolytic or

pyknotic nuclei are very common. Mention has been made of the rifts in

the protoplasm, seen in Herodiones, and this has been observed in other

orders. Perhaps the most striking change is the increase of young

erythrocytes and of thrombocytes in the winged creatures. The nucleus of

the former reminds one of that of the human plasma cell.

The condition of the bone marrow corresponds with fair accuracy to that

which one is accustomed to see in the human being. Certainly this holds

good for the mammals, while among the birds, the few observations upon

which we feel like relying indicate a nodular erythropoiesis of rather

striking character. In the areas of reddening as seen grossly there will

be found under the microscope an orderly arrangement of large red cells

with loose chromatic nuclei about a very much larger cell of the same

type, apparently the primary erythroblast. Outside of this group, red

cells such as appear in the circulating fluid, are rather irregularly

distributed in a marginal zone. I have seen small areas like this in

apparently normal marrow, but the central grouping was not so large as

in the anemic cases; it thus appears that we probably have the anatomy

of erythropoiesis.

The deposition of pigment in the birds is in much coarser granules than

among the mammals, in the former case large masses sometimes obscuring

several liver cells or apparently blocking a lymphatic sinus; the

Kupffer cells do not seem to be heavily laden.

The extramedullary formation of blood cells has been a matter of

considerable interest and study in the human being, and as far as it

concerns the circulating mononuclears, the general opinion seems to be

that such a histogenesis exists. A decision in the negative is perhaps

reached by the majority in the case of erythropoiesis, and as far as my

observations go, this holds for all mammals. It seems worth while,

however, to record an occasional finding in some birds, especially

anemic ones, which may be of importance in their erythropoiesis. The

adult red cell is a clearly formed ellipse with a distinct, deeply

stained, sharply outlined nucleus of a shape corresponding to that of

the whole cell. Young red cells have a more nearly circular outline but

almost truly circular nucleus, the short diameter being at least

proportionately greater than is the corresponding short diameter of the

whole cell; this is also the nucleus whose internal structure resembles

that of the human plasma cell. Groups of such cells have been seen in

the interstices of the liver, sometimes as many as twelve, in a rather

orderly formation. An excess seems at times visible in the spleen but

not in orderly arrangement. Observations are under way toward

determining the relation of this finding to the amount of marrow, the

condition of the blood and the habits of the bird.

Primary Anemia.

As already specified primary anemia is apparently causeless, aside from

the assumption that it is a disease of the marrow itself. Since there

are only four cases, representing three orders and they cannot be

grouped as could the secondary variety, the individual instances will be

discussed separately.

Ring tailed Bassaris (_Bassariscus astutus_). Adult died after two

weeks’ stay in the Garden with a history of general failure of

condition. The diagnosis at autopsy was primary anemia, fatty

degeneration of the liver, hemorrhages in intestines and spleen,

hyperplastic bone marrow. The external appearance is of general good

condition, fair skin, mucous membranes pale. Lungs collapsed, and

gray-red. There are several small hemorrhages scattered irregularly

throughout respiratory tissue. Lymph Nodes—small, soft mottled gray-

red. Pericardium had slight excess clear fluid, and no adhesions.

Heart normal in size, and of pale brown color. The liver of normal

size, smooth surface and sharp edges, of a pale brown color, soft and

friable. Has indistinct markings like yellow brown mottlings on

section surface. gall-bladder contains some viscid brown bile. Spleen,

normal or slightly less in size, consistency firm, capsule pale pearl

gray, apparently not thickened. There are numerous small hemorrhagic

spots on section surface. Interlying pulp is homogeneous deep red.

Follicles not visible. Kidney, normal in size and shape. Trabeculæ

faint. Capsule smooth, strips easily, smooth surface, and brown.

Consistency soft. Medulla prominently striated, cortex homogeneous

salmon pink. Stomach contains a little glistening mucus. Mucosa pale,

flat yellowish, slightly opaque. There is a recent clot lying in some

mucus just above pyloric valve. There is, however, no open vessel

nearby. From pylorus to anus lumen contains some rather fresh smeared

out or slightly clotted blood and mixed in with mucus. Mucosa is flat

translucent, submucosa slightly injected in a mosaic fashion,

otherwise gut wall is negative. No recognizable food present.

Follicles not visible. Mesentery glands small, soft, pale yellow.

Bones seem entirely normal. Marrow of long bones is firm, bloody.

Marrow of ribs also deep red. Blood in intestinal tract is probably a

recent slow oozing from intestinal walls, and was probably the last

straw. Cause of this anemia could not be determined. Blood preparation

not made because it was too long after death. Liver shows moderate

fatty infiltration of marginal areas. Pigment is scarce, only a few

granules being present in the Kupffer cells, not more than is often

seen without marked anemia. There is a slight increase in interstitial

nuclei but not in fibres. No obstruction or increase of bile ducts.

Kidney.—Very mild swelling of tubular epithelium but no exudative

processes. Glomeruli show a few vacuoles but capsular space is

negative to pigment. Bone marrow (Femur) fairly cellular in

construction, but fat well mixed. Cellular areas well arranged,

active, most of cells are small members of the larger mononuclear

variety. Small lymphocytes abundantly represented. Most of the larger

cells are non-granular, with centrally placed nucleus. Megakaryocytes

fairly numerous, nuclei seem closely jammed into centre. No

recognizable certain nucleated red blood cells, moderately number

stippled cells, few adult red cells. Eosinophiles and basophiles quite

few. Pigment small quantity.

This is a case of primary anemia of moderate severity and short

duration, and probably of hemolytic character if one may judge by the

bone marrow, although excessive pigmentation of the liver and kidneys

was not found. Unfortunately the spleen was not minutely studied, nor

was the central nervous system investigated. Atrophy of the intestinal

tract did not exist.

Two cases occurred among the monkeys, but one example will answer, since

the two were essentially the same.

The case to be cited was that of a Japanese Macaque (Macacus

fuscatus). ♀ Young, weight three pounds two ounces, exhibited in the

Garden about four months, and apparently in good shape until two weeks

before death when it rapidly became emaciated.

DIAGNOSIS.—Aplastic anemia, chronic atrophic gastritis. Atrophy of

heart muscle, fibrosis of liver, slight local cloudy swelling of

liver. Perilobular diffuse nephritis (subcapsular type). Congestion of

spleen. Fibrillar fibrosis of spleen. Hemosiderin pigmentation of

spleen. Local amyloid infiltration of spleen. Calcareous infiltration

in medulla of adrenal.

Coat only fair, body emaciated. Pale muscles, fat scanty. Respiratory

tract normal throughout save for slight emphysema. The Pericardium

showed no fluid or adhesions. Epicardium glistening and slightly

thickened. Heart pale in color. Abdomen shows no fluid or adhesions.

Liver slightly decreased in bulk, smooth surface and sharp edges,

hard, and rusty brown. Gall-bladder distended, contained green fluid.

Spleen firm and normal in size. Capsule smooth, shape normal. Section

surface, dark reddish brown, trabeculæ distinctly visible. Kidney,

normal in shape, capsule smooth, strips easily, smooth surface,

glistening, pinkish gray, consistency hard. Section surface, poor

demarkation between cortex and medulla. R. Adrenal, thick orange

yellow cortex, solid small brown medulla. Mouth and teeth normal.

Stomach distended, contains gas and small quantity yellowish mucus.

Mucosa everywhere normal. Postmortem blood examined, stained by

Romanowsky, but red cells were disintegrated possibly by laking so

examination is not satisfactory. Histological Sections: Heart shows

normal epicardium quite free of fat. Myocardium peculiar in that

fibres immediately under epicardium show marked broadening in a very

narrow rather sharply indicated zone where nuclei are extremely large

although not especially chromatic. Transverse markings here easily,

although faintly recognized, have very indefinite borders, their

longitudinal fibrillæ being ranged in form of a coarse reticulum. This

comes about from frequent and extensive lateral anastomoses with

fellow fibres giving appearance of a syncytium. In deeper parts,

fibres are of more normal size but nuclei are still large and fibres,

now cut in transverse section do not appear to anastomose so freely;

there appears to be a slight excess of fibrous tissue in their deeper

parts. Arteries quite normal. Atrophy with regeneration.

Liver.—Capsule and interstitial parts on whole normal. Perilobular

fibrous tissues largely missing, but where remaining show an

overgrowth occurring in peculiar zonal arrangement and of old adult

almost hyaline type. Its fibres are often arranged strikingly in

whorls. Bile ducts, arteries and veins quite normal. Parenchymal cells

of normal size, finely granular, prominent normal nuclei and contain

small quantities of finely granular, golden brown pigment not really

as abundant as commonly seen in severe anemias. Blood capillaries

narrow, contain small quantities R.B.C., and Kupffer’s cells very

frequently contain fine granules like those of parenchymal cells but

of a greener tint. In a few isolated areas parenchymal cells

distinctly more swollen than others and many show disintegration of

nucleus. Hemosiderin pigmentation. Perilobular fibrosis. Slight local

cloudy swelling.

Kidney.—Capsule smooth, interstitial fibrous tissue of organ proper

highly fibrosed in peripheral parts, but slightly in deeper. No

lymphocytic infiltrations anywhere or sclerosis of vessels. Tubular

epithelium highly atrophic in subcapsular regions where tubules are

narrow. In deeper parts epithelium is at times so swollen as to

occlude lumina, where they are coarsely granular and occasionally show

some karyolysis, a pink hyaline or finely granular material. Tufts

never show fibrosis, normal size. Bowman’s capsule heavily thickened.

Chronic diffuse nephritis (subcapsular type).

Spleen.—Slightly hyalinized capsule, normal thickness. General

reticulum of pulp slightly fibrosed and poor in lymphocytes. Sinuses

broad, crowded with red blood cells, but only small numbers of

lymphocytes. Coarse granular blood pigment abundant, showing greenish

cast on focusing. Malpighian follicles normal size, slightly fibrosed,

and in several instances show a deposit of smooth pink material

between cells. Congestion. Fibrillar fibrosis. Hemosiderin

pigmentation. Local amyloid infiltration.

Adrenal.—Organ appears normal in all respects save for presence of a

few small irregular areas of calcification in medulla. These occur

apart from any recognizable necrotic or fibrous areas. In one place

one appears to lie within lumen of blood vessel. No fibroses or

special congestions anywhere in organ, and cells show normal details

and normal numbers of vacuoles. Calcareous infiltration of medulla.

Stomach.—Muscular tunic normal. Submucosa thin, has densely arranged

bundles of smooth, pink character. Mucosa distinctly thinned, shows

comparatively few regions holding acid cells, consisting for most part

of peptic type of gland. These are short and of broader calibre

towards lumen than deeper, suggesting a hyperplasia of luminal

portions; stroma richly infiltrated with lymphocytes, not fibrosed or

congested. Epithelium of crypts has rarefied appearance, shows no

special degenerative changes. Chronic atrophic gastritis.

Bone marrow appears as widely separated large, fat globules with

intervening granular edematous material and no hematopoietic elements.

Blood capillaries numerous and highly congested.

Although the notes fail to discuss the gross appearance of the bone

marrow, the amount of alteration in its microscopy and the relatively

small output of pigment in the liver, seem to substantiate the

determination of aplastic anemia; it is unfortunate that the blood

smears could not be used in the decision. At all events the condition of

the intestinal tract, of the heart, liver, spleen, and adrenal, justify

us in classing the case as one of primary anemia. The next and last

instance is of the same type, although I am inclined now to differ from

the diagnoses made at the autopsy table, that of aplastic anemia, and to

place it in the hemolytic variety. The rapidity of the fatal attack, the

redness of the marrow, the excessive pigmentation, and the prominence of

recent degenerative lesions in the organs are much more like the changes

of a primary hemolytic intoxication than of an aplastic anemia.

Gray Fox (_Canis cinereo_). ♂ Weight four pounds, adult, was in the

exhibition two years, but in good condition until two weeks before

death, when it stopped eating and rapidly fell away.

DIAGNOSIS.—(Aplastic) Primary anemia. Zenker’s Hyaline of heart and

skeletal muscles. Mucoid degeneration of bone marrow. Congestion of

bone marrow. Atrophy of hemopoietic elements in bone marrow.

Hemosiderin pigmentation of liver. Atrophy of liver. Congestion of

liver. Congestion and fatty infiltration of kidney. Patulous lumina in

adrenal and absence of pars glomerulosa.

External appearance of coat good. Decomposition advanced in

intestines. Skin and subcutaneous tissue faintly yellow. Poorly

developed, dark muscles and fat. Respiratory tract normal throughout.

Pericardium glistening, transparent, and pale, with no adhesions.

Heart a little too pale, consistency slightly soft. Normal or slightly

increased size of liver, with smooth surface and sharp edges,

consistency friable, and of a brownish red with rusty coloring. Spleen

normal. Kidney normal in size, shape, location, and consistency.

Capsule strips easily, and of a faintly yellow, under general red,

coloring. Adrenal normal. Mouth and teeth normal. Stomach, serosa and

wall normal. Mucosa shiny, autolytic, muddy red. Ileum, agminated

follicles swollen. Feces from colon examined microscopically. Pancreas

normal. Bone marrow tibia and femur gelatinous and red, not slightest

trace of yellow. Blood films from heart’s blood show poikilocytosis

and anisocytosis; only one nucleated red.

Microscopic Notes.—Heart has torn but normal pericardium. No

abnormalities of interstitial tissue or vessels. Fibres of normal

width but show transverse markings irregularly since cytoplasm becomes

hyaline and swollen in many places along its course. Nuclei prominent,

slightly pyknotic. Zenker’s Hyaline.

Bone marrow consists of a matrix of granular or fibrillar mucoid

tissue within the delicate reticulum of which highly developed

capillaries are placed, together with stellate spindle and sealring

cells. In a few places only are myelocytes recognizable and then in

decreased numbers. Plasma cells sometimes found containing much blood

pigment.

Liver.—Capsule normal; perilobular fibrous tissue only slightly

overgrown, moderately infiltrated with lymphocytes and heavily with

blood pigment. Arteries, ducts, veins, normal. Parenchymal cell a

little smaller than normal with nuclei of normal type, and crowded

with fine granules of blood pigment. Latter lie in usual

pericanalicular position. Blood capillaries narrow, moderately

congested and Kupffer’s cells also contain abundant pigment granules.

Thyroid.—Interstitial framework shows no fibrosis or cellular

infiltrates. Blood vessels normal. Acini fairly uniform in size, none

ever attaining large proportions, but some being distinctly below

normal. They are uniformly filled with a very pale pink hyaline

material which in some way gradually increases in color intensity

toward one side, attaining in a few examples usual intensity of

colloid. Lining epithelium is low cuboidal, shows no special

hyperplastic features or atrophy.

Kidney.—Capsule normal. Interstitial tissue normal. Blood vessels

slightly congested. Tubular epithelium granular, disintegrated and

frequently contains numerous fat globules and obscured nuclei. Lumina

of about normal size containing variable quantities of pink granular

detritus. Glomerular tufts normal in size and appearance. Subcapsular

space and Bowman’s capsule normal.

Adrenal.—Capsule and pericapsular tissue normal. Parenchymal cells

throughout poor or practically free of vacuoles, such appearing in

only limited portion of pars vesicularis. Interstitial framework and

vessels normal. Structure of columns in pars vesicularis is peculiar

in that they extend quite to capsule with no intervening pars

glomerulosa, and again in that most peripheral parts are expanded at

times showing a lumen, while deeper parts show broad cells extending

fully across the column. Pars reticularis contains no pigment and

medullary cells quite normal. Skeletal muscles show comparatively few

fibres with transverse markings. Most are swollen, hyaline, lumpy, and

have pyknotic nuclei. Interstitial parts show no inflammatory change.

Tissues treated by Prussian blue test for iron. Kidney, adrenal, heart

found to contain none. Spleen, liver contain abundance. That in spleen

responds to test showing that it is all iron containing. Two kinds of

pigment found in liver. In periphery of lobule as much contains iron

as that which does not, while in deeper parts iron predominates. Many

times both kinds are recognized in one cell. On the whole it is the

finest granules which contain more iron (are bluer) while iron free

pigment occurs in bile canaliculæ. That in Kupffer’s cells stains

strongly blue.

SUMMARY OF PRIMARY ANEMIAS.

A review of these instances of grave anemia brings one to the conclusion

that there is a strong similarity to the disease in man. Perhaps we have

constructed a picture that is too narrow for the animal kingdom in

general, but surely these few instances deserve to be distinguished from

the secondary cases already presented if for no other reason than that

no associated etiological condition was exposed. It was hoped in

studying the anemias of lower animals, and this hope extends over all

the subject of this book, to be able to throw some light upon causation.

The thought of incorrect diet came at once, but we are confronted with

the paucity of cases among our records. Moreover, secondary anemia from

digestive and dietetic troubles is clear, but how we can use this

argument for an essential change in hematopoiesis and natural

hematolysis, is far from evident. It will be noticed that I have

studiously avoided grouping any case with parasites among the primary

cases, nor will there be found any evidence of generalized infectious

disease. Most of the reported instances of pernicious anemia in the

lower animals have been associated with one or other of these factors,

although certain authors (Kitt, Hutyra and Marek) maintain that a

causeless variety probably exists.

LEUCEMIA.

This condition is fairly well recognized by veterinarians as occurring

among domesticated animals, but in the records of this Garden it has

occurred rarely, indeed only once in a mammal and but five times in

birds. It is interesting that, in the wealth of material at the disposal

of Plimmer and his associates, only one case, a polecat with lymphatic

leucemia, is noted, and but very few avian instances. Herewith is

submitted the protocol of our single mammalian case; perhaps we have

missed others of a mild grade dying during the early stages because

their resistance to infection was reduced. Unfortunately, perhaps

because of the postmortem changes, but more likely because it appeared

at first as if we had to do with a case of generalized tuberculosis, the

bone marrow in this case was not examined. Nevertheless the infiltrative

character of the lesions, the absence of distinct tumors and the

numerous mononuclears in the blood as seen in sections seem to justify a

diagnosis of leucemia, in all probability of the lymphatic type. There

follows this case one with similar gross and microscopic picture which

has no visible increase of leucocytes, but a very distinct myeloid

picture in many places.

Common Opossum (_Didelphys virginianus_). ♂ Adult. No evidence of

illness. Found dead. Lymphatic leucemia (involving all viscera and

lymph nodes). Diffuse nephritis. Both lungs have become entirely

involved in a firm, gray-yellow mass not adherent to any serous

surface. Practically no normal lung tissue is left. This seems like

tuberculosis but no tubercle bacilli could be found in a good smear.

Estimation of the normal cubic capacity of an opossum lung was made to

be about five cubic inches. In this case not over one-half cubic inch

remained respirable. Bronchial lymphatic glands were enlarged, firm,

yellow gray, with no recognizable lymphatic tissue. Heart muscle was

firm and flaccid, pale and striated. Liver very large, firm and tough,

with smooth surface and sharp edges. Color pale brown. Section surface

glistening, dry, smooth, opaque. Common bile duct patulous. Spleen,

slightly increased, firm, tough consistency, capsule smooth. Section

surface, smooth, firm, brown-red, pale pulp, prominent follicles, and

trabeculæ faintly visible. Right kidney, slightly decreased, normal in

shape. Capsule smooth, strips with difficulty, tears surface. Surface,

granular, color brown, consistency firm. Thickness of cortex, narrow

irregular, markings irregular and obscure. Small mass of fibrous

material in cortex about 3 × 3 mm. like those in lungs. There are also

numerous pale yellow gray areas in cortex and outer medulla, round and

streaky, distorting the striated architecture. Right adrenal converted

to a yellow gray mass like lungs. The mesenteric and retroperitoneal

lymph nodes are firm, gray-yellow. This includes those under diaphragm

and around cœliac axis.

The histology of the organs may be described together. The infiltrate

described is a densely packed mass of large cells with large, well

staining nuclei and a very narrow rim of protoplasm. It is not limited

by any definite wall or septa. It has no interstitial tissue. There is

no blood supply in the densest masses but the walls of the blood

vessels remain intact wherever the mass surrounds them. In the lungs

it has involved all structures indiscriminately, and has destroyed

practically all of the respiratory surface. It seems to follow by

preference the peribronchial space. A few glands may be seen in the

centre of this mass, but they are rapidly undergoing degeneration. In

the liver the infiltrate is chiefly beneath the capsule extending

inward but a very short distance. There are no large masses as in

other organs but small infiltrates are seen at the portal areas. The

spleen shows a diffuse excess of pulp cells and many of the cells

above described, the difference being only in the size of the nucleus

which is smaller in the pulp cells. There are very small round cells

relatively. Follicles are absent, connective tissue not altered. Note

states follicles prominent; this is due to nodal hyperplasia of the

large mononuclears above described. The parenchyma in the kidney is

anemic, the epithelium is slightly pigmented but this is probably not

abnormal. Between the tubules especially of the outer layer of the

medulla and medullary ray but also in the cortex and around the

glomeruli are diffuse, irregular, infiltrating masses of the cells as

described above. In some places in the kidney hyaline casts are being

formed probably due to the degeneration of the epithelium by pressure.

There are a few distentions of the tubules. The capsular space is

free. In the neighborhood of the collections the capsules are a trifle

thicker than normal. Lymph nodes, similar to spleen in that most of

the bodies are thoroughly overrun with the large mononuclears. The

sinuses, both marginal and internal, are practically obliterated by

these cells. In the blood vessels of the lungs and liver there are

many large mononuclears, perhaps not as large a number as might be

seen in leucemia, but decidedly in excess of normal.

Common Marmoset (_Callithrix jacchus_). ♂ Adult. Had cage paralysis

for two months before death and declined gradually from that time.

DIAGNOSIS.—Bronchopneumonia. Myeloid hyperplasia of bone marrow.

Myeloma in pancreas. Fatty degeneration of liver. Constipation.

Nematodes in cecum. Animal is thin, skin bare in spots. Both lungs are

pale pink with large areas of deep red consolidation. Heart is

dilated, increased in size with firm, red-brown muscle. Liver is firm,

red-brown, with smooth surface and sharp edges. Section surface is

glistening, smooth and moist. Lobular outlines are clear by reason of

pale lines. The gall-bladder is normal in size and contains fluid pale

green bile; duct patulous. Spleen is normal in size, smooth capsule,

soft, purple pulp, follicles small and faint, trabeculæ fairly

prominent. Kidneys normal in size and shape. Capsule smooth. Section

surface smooth and brown and firm. The glistening section surface has

a narrow cortex, swells slightly, with prominent striæ. Intestines

throughout are pale on serosa. Wall thin. Mucosa flat, pale pink.

Contents creamy mucus in the upper intestine. Large intestine contains

large masses of very firm feces. Cecum is distended with feces and a

great quantity of nematode worms. They are not attached to mucosa nor

does mucosa seem altered because of their presence. Skeleton and

muscles.—Long bones of extremities break easily, but with snap. Skull

can be dented with fingers. Bone marrow of femur bright red.

MICROSCOPICAL NOTES.—Liver shows moderate degree of fatty degeneration

with capillary congestion. Kidneys negative. Some postmortem change in

last two organs. Spleen, marked congestion. Hyperplasia of large lymph

cell type, particularly in follicular centres. Blood destruction

moderate. Bone marrow seen in condition of marked activity of myeloid

type. Aside from enormous crowding of strands there does not seem to

be any atypical cell. Intestines show practically no change. Same

condition holds in pancreas. In several places in pancreatic ducts

cross sections of nematodes may be found. In among lobules of pancreas

is a well encapsulated cellular mass without particular architecture.

It consists of cells of large lymphocyte or endothelioid series. There

are numerous cells of size and staining characters of small

lymphocytes. There are no megalocytes but there are some

indistinguishable from myelocytes. This may be an intrapancreatic

lymph node. One small lymph node found in section; it shows a picture

quite like the marrow except for megalocytes. Blood vessels do not

show an excess of leucocytes in free or coagulated blood.

Perhaps this latter case belongs to the aleucemic leucemias or

pseudoleucemias. These two conditions are recognized by the difference

in circulating leucocytes, a piece of information not at our disposal.

The whole subject of hemato-lymphatic affection must remain unsettled in

so far as a diagnostic name is concerned, for in very few cases has the

blood of our animals at autopsy been in a state permitting reliable

observations upon stained smears, because of coagulation, lysis or

decomposition. After considering a few more of the diseases of the blood

and marrow, the lymphatic apparatus will be considered. But there is a

borderland to which a word might be devoted at this time, that group to

which various names—Hodgkin’s disease, pseudoleucemia, general

adenopathy, adenie, aleucemic leucemia—have been applied and which has

been accepted as occurring in the domesticated animals. Since I have

been occupied for several years in a study of this clinicopathological

complex in the human being, such cases have been searched for most

diligently, but without success. The New York Zoological Park records a

case of Hodgkin’s disease, without specifications, in 1901, and at the

London Garden a pseudoleucemia was found. The paucity of leucemia and of

the aleucemic adenopathies in lower animals and their relative frequency

in man excite speculation as to their interdependence; but more of this

under the lymphatics.

AVIAN LEUCEMIA.

The class Aves is rather better represented in the group of leucemias,

but here the well known infectious disease may confuse the picture. The

birds affected were Psittaci 3 (1 parrot, 1 parrakeet, and 1 amazon),

Herodiones (stork) 1, and Galli (Gambel’s quail), 1. There was no close

association of these cases either in time or housing. One of the parrots

and the stork had a picture suggesting that given by Warthin for avian

leucemia while the remainder presented greater evidence of a generalized

infection, such as Moore described, associated with the finding of the

B. sanguinarium; this organism was isolated once, but no secondary cases

succeeded upon the death of this bird. It seems hardly profitable to

quote protocols of this relatively unimportant condition, especially

since it is fairly well known.

The separation of the two groups just specified might be discussed,

however, for it is by no means certain that they are or are not

different. When a pathological picture of leucemia gives a decided

impression of an acute infection there are very prominent involvements

of the viscera but no lymph nodal masses. On the other hand, in the

cases with nodular masses corresponding to the scanty lymph tissue of

birds, there is much less infiltrative involvement of viscera and less

parenchymatous degeneration. This suggests that they are different

processes, but an analogous contrast may be found in the pathologic

anatomy of acute and chronic leucemia in man, and I am inclined to view

them as stages of the same disease. In one of our infectious cases noted

above the lesion was certainly myelogenic for the infiltrate in the

organs and the cells in blood smears showed an enormous number of

eosinophilic and basophilic polynuclears greatly in excess of normal.

The study of two of our cases confirms the picture as given for

lymphatic and myeloic leucosis by Ellermann[18], but material

corresponding to his lymphoidocytes or erythroleucotic group has not

come to our attention. Cells with deeply staining basophilic protoplasm

and a lymphoid nucleus are certainly to be found with reasonable ease in

the avian marrow normally and, more than this, can be detected by

careful search in nearly all cellular infiltrates of organs not leucemic

in nature. Perhaps, as Ellermann states, they are collateral stages in

normal erythrogenesis.

THE BONE MARROW.

Since the foregoing conditions so vitally concern the bone marrow, it is

but natural to give to this structure a separate consideration. From

what is known of the origin, physiology, anatomy and regeneration of the

marrow from the work of Ponfick, of Neusser, Bunting, Selling, Werigo

and many others, it seems highly probable that the principal conclusions

reached in the study of human medicine and experimental pathology, apply

to the whole group of animals here under discussion. The peculiar

arrangement already mentioned as encountered in the marrow of birds

differs little if any from the erythropoietic centres seen in man after

experimental anemia, although it may be somewhat more orderly.

Myeloblasts or megakaryocytes are not numerously present in any order,

but seem more prominent in the mammals than in birds. In so far as the

mononuclear groups are concerned, one can state with reasonable

certainty that they differ little throughout the animal kingdom. They

occur in islands, strands, or infiltrate—like groups, are mixed granular

and non-granular in character and, with exception of the frankly

oxyphilic cells, are distinctly basic in tinctorial affinity. In a case

probably myeloma, soon to be discussed, there is not a single

acidophilic or multinucleated cell to be found in two sections. As might

be expected from the greater eosinophilic content of the circulating

blood in the Aves, greater numbers of such cells are to be found in the

marrow and they are, understandingly enough, sometimes found in distinct

nodes and groups containing mono- and polynuclear varieties. Concerning

the platelets, no sufficient data are at our disposal to warrant a

general statement. In the avian marrow they can be made out quite

clearly, as in the blood, and have a greater diameter and a sharper,

more chromatic nucleus than in the higher mammalian blood. Mast cells

are quite common in lower mammals and birds, in whose blood they

maintain an appreciable percentage, while in the marrow they stand out

clearly. It is noteworthy, in the light of Graham’s statement that the

hemic basophile is but a degeneration form of the eosinophile, that in

the bird’s marrow, large mono- and polynuclear cells with both kinds of

granules easily may be found by Romanowsky stain. An increase of

eosinophiles, seen in avian as well as in human parasitism, is not

necessarily accompanied by basophilia.

Hyperplasia and atrophy of marrow in the lower mammals follow much the

same conditions as in higher groups. During acute general infections, as

by the paracolon bacillus in carnivores, it is common to find a distinct

increase in the mononuclear centres, while in suppurative lesions a

polynucleosis results. The bird, however, responds less readily with

leucocytes, judged by cross sections of blood vessels and the activity

of the marrow. The latter may show a myeloid picture, but mononuclears

without granules, with deeply staining nucleus and protoplasm, are

usually more numerous; two cases recently studied, one of tuberculosis

and one of pneumonia with general congestion, had similar bone marrow—

pale homogeneous red with distinct mononucleosis, more outspoken,

however, in the former case. Pigment is not common in the avian marrow.

The relation of the marrow to general conditions has been mentioned in

the foregoing pages, but perhaps the following diagnoses will illustrate

other connections seen among our records:

Bactrian Camel (_Camelus bactrianus_).—Hydatid disease of lung and

liver. Hemorrhagic enteritis. Atrophic bone marrow. Calcified areas in

thyroid.

American Gray Wolf (_Canis mexicanus_).—Cretinoid. Hemorrhagic external

pachymeningitis with craniotabes. Secondary hyperplasia of thyroid with

colloid. Chronic lymphatic hyperplasia. Chronic interstitial nephritis.

Chronic enteritis. Osteogenesis imperfecta. Hemorrhagic bone marrow.

Concentric hypertrophy and dilatation of heart.

MYELOMA.

Perhaps no pathological condition has given rise to more varied opinions

than the tumor-like hyperplasias of the bone marrow, growths resembling

bone sarcoma with and without giant cells—myeloma, chloroma,

pseudoleucemia ossium and many others. In brief only two cases occur in

our series which could be admitted to this category. There have been

osteomata, but they were so clearly local tumors that they cannot be

included in myeloid neoplasms that are assumed to be systemic in nature.

Here is not the place to engage in a discussion of the correct

classification and nomenclature since there are included only the

aleucemic newgrowths usually assumed to originate from blood-making

cells. The first case seems to be a myeloma because of the involvement

of many bones and the infiltrates in the liver. Judging by the cross

section of blood vessels there is no leucemia, but of course this is not

final, although somewhat supported by the normal size of the spleen and

lymph nodes; lymphatic structures need not be enlarged in myeloid

leucemia although they usually are.

Beechy’s Gopher (_Citellus grammurus beecheyi_). Adult ♂ . Gradual

loss of power in limbs beginning about two weeks ago. No other

symptoms.

DIAGNOSIS.—Multiple myeloma. Anemia. Acute parenchymatous nephritis.

Chronic ulcerative gastritis.

External Appearance.—General condition fair, hair in good condition.

Fully developed animal. Muscles contained no fat.

Respiratory Tract.—Thymus, large soft gray homogeneous. Both lungs are

distended, pale, homogeneous, yellow pink, boggy, do not crepitate,

but contain no edema. Lymph nodes, small soft anthracotic. Pericardium

contained no fluid.

Abdomen.—No adhesions. Size of liver normal or slightly small, firm

and pale brown-red. Architecture irregular showing areas of perfect

homogeneity and others where lobules are clear outlined by paler

interstices. Gall-bladder distended, contains brown fluid. Common bile

duct, patulous. Spleen, normal or slightly small, consistency soft,

capsule smooth, location normal; section surface, homogeneous pale

pulp, faint trabeculæ. Kidney normal in size and shape, capsule

smooth, strips easily, smooth brown surface; section surface

glistening, opaque; consistency firm; thickness of cortex normal and

of medulla normal; homogeneous cortex, glomeruli not visible.

Adrenal.—Narrow, brown, opaque cortex; pale brown, opaque medulla.

Bladder, small quantity of cloudy urine showing albumin, bile and many

granular casts, few hyaline casts. Teeth carious broken; mouth pale.

Stomach distended; serosa and wall pale, contained gas; mucosa pale,

flat, translucent except in pyloric segment where it is slightly

thickened, irregular, opaque and there are several saucer shaped

depressions covered with black, shiny material; these seem like

sluggish ulcers. Intestinal tract throughout seems normal save for its

pallor. Few natural fecal masses in lower gut.

Skeleton and Muscles.—All bones are irregular in thickness, very

brittle and show in their length irregular swellings made up of

periosteal growth and probably increase in marrow. The latter is pale

yellow with punctate hemorrhages. Skeleton seems too soft to give

support, but there is little deformity.

Microscopy.—Bone section shows a myelomatous growth of costal marrow,

new myelocytes predominating. The cells are packed in disorderly

fashion through the marrow. They are chiefly lightly granular but a

few distinct promyelocytes are found. The hyperplasia is invading

cartilaginous bone with absorption. In some places cartilage is of

fetal type. Perichondrium is active but there is no round cell

infiltration. Ossification is imperfect at costochondral junctions.

Kidney shows granular and vacuolar degeneration of epithelium with

flattening of tubular lining. Nuclei are for most part normal.

Epithelium of tufts and Bowman’s capsule is likewise granular and

vacuolated. Distal and discharging tubules seem to be most affected.

No well defined casts are found.

Liver.—The fine markings mentioned in the notes correspond to areas of

infiltration of large pale mononuclears without granules. There is no

fibroblastic or polynuclear increase around them. Very small necroses

seen in hepatic lobules. Very slight increase of connective tissue is

noted.

This seems to be a tumor of true myelocytic origin; none of the cells

was of the plasma type as usually depicted. The second case stands in

the files as a myeloma, yet the full description and slides have been

mislaid. It is cited briefly for record.

Samoli Ostrich (_Struthio molybdophanes_). Adult ♂ . Would not eat for

three weeks.

Diagnosis.—Tuberculosis of lung, liver, spleen, kidney, mesenteric and

cervical lymph glands. Myeloma of periosteum of pelvis.

Skeleton and Muscles.—Large tumor mass lying on inside of pelvis

measuring about ten inches by twelve inches with a thickness of about

four inches. It is sharply defined and separated from adjacent muscle

by a capsule. Inner border is directly below the peritoneum, and outer

border lies directly on bony pelvis. Traced to its origin it seems to

come from pelvis yet tumor peels off bone easily, leaving a rough

surface. The tumor is soft and succulent, of a red gray color and

contains some fat and much irregularly placed masses of bony tissue.

SECTION V

DISEASES OF THE LYMPHATIC TISSUES INCLUDING SPLEEN

Since we have followed diseases of the blood from the simple anemias to

a place where mononucleosis in the circulatory system and in the fixed

tissues is the prominent feature, another step reaches the area whence

most of these cells emanate—the lymphatic system. The anatomical and

physiological position of the lymphatic circulatory apparatus is closely

analogous in the classes under discussion, and it stands in an

anatomico-clinical sense, closer to the hematopoietic system than to any

other structures, throughout the whole animal creation. This anatomical

division of the circulation is closely comparable, for pathological

purposes, in the mammals whereas in the birds one finds noteworthy

variations. In the class Aves lymphatic radicals are extremely numerous,

the plexuses in the extremities and thorax perhaps being complemental

for the rather scantily supplied blood vessels. About the fibulo-tibial

and femoral muscles the tiny lymph vessels form an extraordinarily dense

and intricate lacework, a replica of which may be found in muscles of

the upper limb, while in the pelvis and thorax a rich plexus is

distributed around both kinds of blood vessels and also lies within the

walls of air sacs. The air sac walls in the chest display lymphatic

lines very well in birds that have been for many years exposed to

railway dust, the natural pearl gray glistening membrane looking as if

black pepper had been evenly dusted over it. The lymph glands or

compound nodes so easily discovered in mammals are practically absent in

birds. Along the large thoracic vessels and in the pelvis of some

anserine and struthious varieties, small illy defined masses of

lymphatic tissue may be discovered by careful search but they do not

possess nodal arrangement and capsule. Lymph follicles on the other

hand, are quite numerous in the respiratory, and especially, the

intestinal tract. Groups of follicles may also be found in the lining of

the upper ends of these tracts in such situations that the names

faucial, pharyngeal, or even tubal tonsils are justly applied. I do not

find any reference to a lingual tonsil in birds, but this structure is

found, with of course many modifications, down as far as the monotremes.

The lymphoid tissue of the nasopharyngeal region is so placed in animals

as to be exposed to aerial and food infections, just as it is in man. It

is, however, noteworthy that chronic inflammations leading to

hypertrophy or to obstruction have not come to our attention. There is

only one diagnosis of chronic tonsilitis in our records, a determination

based upon the nodular red-brown prominence of the tonsillar region, but

there were no true hypertrophy and areas of fibrosis combined with

necroses as seen in human medicine; this case concerned a Chacma baboon.

HYPERPLASIA.

In so far as the reaction to infectious or toxic agents is concerned

there seems to be a fairly uniform character through the mammalian

groups, but in the Aves there are a few differences worthy of mention.

It is at once admitted that these observations upon birds are based upon

a very few sections of isolated lymphatic tissue, but they are supported

by records of the changes in nodes in mucous membranes and viscera, and

by those in the spleen. The first and perhaps most noteworthy difference

is in the paucity in birds of large mononuclears of the endothelial

type. Their position in chords, sinuses and germinal centres is taken by

deeply staining mononuclears, of the size and general character of large

lymphocytes as seen in the blood. The hyperplasia in the follicles is

much more dense but it is outdone by that in the chords. Since the nodal

tissue of birds is not so sharply delimited by some sort of capsule, it

is but natural that the hyperplasia should be diffuse; in the intestinal

wall it may extend laterally twice or thrice the width of the normal

follicle. Necrosis, unless the disease be mycotic, tuberculous or

parasitic, is uncommon.

It may be well to discuss for a space the reaction to infection of the

thoracic and intestinal lymphatics in mammals. The amount of

lymphadenoid tissue in the mediastinum is very great in some mammals,

notably the Ungulates, while in others, the Rodents and Primates, for

example, it is not so plentiful. Nevertheless the gross and minute

changes are usually of the edemato-exudative type—large, pink, soft,

moist glands. In the abdomen, on the other hand, one usually finds well

outlined, firm, yellow nodes in the mesentery and behind the peritoneum.

This is not only to be discovered in various chronic diseases of the

intestine but even in acute, so-called toxic enteritis seen in

carnivores from food poisonings. One must therefore ask if the local

nodes abundant in the intestinal mucosa do not take up the poisons which

cause the acute hyperplasia and are in turn backed up by the stalk

glands. Even in so acute and overwhelming a disease of the intestine as

hog cholera (which we have not had here) the glands retain their general

structure, although hemorrhagic, while in late stages they become firm,

sharply outlined and pigmented. In birds there may be swelling of the

omental bursæ, but as there are no lymph glands no masses are found.

The response on the part of the lymphatic tissues as a system, or some

large section of this system, is shown in the following figures. It is

our practice to include in the diagnosis general acute or chronic

lymphadenitis or inflammation of a large drainage area. Acute changes

have been mentioned 103 times, in which the important orders are

represented as follows: Primates 21, Carnivora 46, Ungulata 15, Rodentia

3, Marsupialia 13, Pinnepedia 4. Chronic changes are mentioned 43 times

as follows: Primates 7, Carnivora 19, Ungulata 14, Marsupialia 1, and

Pinnepedia 2. This great proportion among the Carnivora does not

indicate that they have more lymphatic structures for such an advantage

is probably possessed by the Ungulata, but perhaps should be interpreted

as an evidence for this order of the ready response to irritation on the

part of the tissues in question. They probably suffer more, as we shall

see later, with inflammation affecting drainage tracts. The hyperplasias

or inflammations included in the figures above most often accompany

gastroenteritis, pulmonary diseases or long standing infectious

processes such as arthritis, while there are also lymphatic enlargements

both local and general, associated with skeletal degenerations

(rachitis-osteomalacia) and with thyroid disease. The former may be

described as lymphadenitis, the latter as lymphatic hyperplasia.

Unlike lymphadenitis, a condition associated with some definite

infectious or toxic cause, systemic hyperplasia of the lymphatic tissue

may be apparently primary and causeless. In a pathological and clinical

sense alike these hyperplasias are protean in their manifestation,

making a satisfactory classification extremely difficult. For our

purposes they are divisible into acute and chronic, associated with an

increased number of circulating lymphocytes and without such a

lymphocytosis.

The first, acute systemic lymphatic hyperplasia, is known in man as

status thymicolymphaticus, a well recognized condition chiefly

encountered in youthful males having some of the stigmata of the

opposite sex. There is no record, nor have I any recollection of a

pathological state in a wild animal comparable to this condition.

If acute generalized lymph node increase be associated with

lymphocytosis, acute lymphatic leucemia exists; there is no case in our

records. Chronic enlargement of lymph nodes with increase of circulating

mononuclears is chronic lymphatic leucemia; a case of this has been

cited under leucemia.

LYMPHOMATOSIS.

Chronic enlargements of the lymphatic tissues without leucemic blood

present a bewildering number of varieties, the best known names of which

are Hodgkin’s disease, aleucemic leucemia, pseudoleucemia and

lymphomatosis. On occasion they are at first localized tumors, being

generalized only late in the course; under these circumstances they are

usually classed with neoplasms in the form of leucosarcoma and

lymphosarcoma. Examples of lymphatic disease answering the above

description are limited to two, but even these must be explained in

certain particulars. There has already been quoted under leucemia a case

of a common Marmoset (_Callithrix jacchus_) which was probably aleucemic

leucemia of the myeloid variety; the enlargement of lymphatic nodes was

trifling. The case to be cited answers in most respects to the

descriptions of systemic lymphomatosis, but there were found two

conditions, enteritis and parasitism, which might be responsible for

sufficient general toxemia to stimulate lymph nodes and follicles to a

state of active growth. Even accepting these two cases as examples of

this group, it is very plain that chronic systemic primary lymphatic

hyperplasia is an exceedingly rare entity in wild animals. There has

been no case resembling Hodgkin’s disease of man.

California Hair Seal (_Zalophus californianus_). Young ♂ four months

old. Appeared to be in good health, no loss of flesh or activity.

DIAGNOSIS.—Lymphomatosis. Fatty degeneration of kidneys. Emphysema.

Chronic follicular and catarrhal enteritis. Nematodes in intestines.

External appearance good. Both lungs distended and are tense; it seems

almost like a spastic dilatation—a simple emphysema—beneath pleural

surface are many minute petechiæ. Lung mottled red and gray. This

color is present on section. Lobules clearly outlined and separable

with fingers. Bronchi and vessels widely open, the latter containing

small amount of fluid blood. Lymph nodes—Mediastinal, tracheal and

those visible in neck are variously but definitely enlarged, firm,

irregular and roughly nodular, both in appearance and to touch. On

section they are red and gray, follicular border not preserved and

merging with medulla; connective tissue visible; gray juice expressed.

Pericardium normal. Epicardium, glistening, transparent and pale.

Heart position, size and interior normal. Abdomen contained no

adhesions or fluid. Pale brown-red, firm liver with smooth surface and

sharp edges; markings not clear; section surface smooth; watery blood

expressed from section. Gall-bladder normal, contents limpid, brown.

Common bile duct patulous. Somewhat enlarged spleen, soft, yet

resilient; capsule smooth; section surface pulp homogeneous brown-

purple; follicles gray, slightly enlarged, clear, sharply outlined;

trabeculæ faintly visible, more prominent where they are near

follicles. Kidney normal in size, shape and location, with smooth,

pale brown surface; capsule smooth, strips easily, section surface

glistening, consistency soft yet resilient; thickness of cortex

slightly wide, of medulla normal; individual lobules clear yet no

increase of connective tissue between; pyramids quite pale; top of

medulla a little darker; cortices, pale, striæ quite faint and seem

irregular; glomeruli not visible. R. Adrenal—In upper pole are two

cysts about 1.5 and .8 cm. across; no scar at this point. L. Adrenal—

Wide pale purple, regular homogeneous cortex under very dense capsule;

medulla reddish brown, homogeneous, quite bloody. In left adrenal is a

pale gray, fairly well outlined area between medulla and cortex at

upper pole about 3 mm. across.

Stomach.—Contains glass and stones; mucosa, soft, smooth, flat, yellow

and pink, translucent rugæ; cardia about normal; pylorus, valve

prominent but probably not hypertrophied. Duodenum—Beginning at

pylorus and extending through to ileum where follicles commence,

intestine contains small amount white, creamy material, serosa

negative, mucosa smooth flat, pale pink, translucent. There are small

nematodes, probably uncinaria, some of which are attached quite

firmly. Here and there throughout the gut are bits of thickened mucosa

or submucosa, 2–5 mm. across. Some of these have a tiny opening from

which clear fluid can be expressed. Ileum shows smooth flat

translucent mucous membrane; empty; individual follicles faint but

discernible. Colon reddened mucous membrane, nematodes and little

mucus. Pancreas, soft, normal in size and position, color pink gray.

The lymphatics of peritoneal cavity are all enlarged; most of

retroperitoneal are also. Regional lymph glands are also enlarged. The

description given for mediastinal answers here. The glands of

mesenteric stalk present chain of sausage-like masses. Glands in

mesentery are but slightly affected. Glands within and without

peritoneum at kidney are especially enlarged. Large gland behind

stomach and pancreas and in front of upper end of spleen is much

enlarged, thick and roughly circular; it shows much fibrosis. The

regional glands are distinctly enlarged but proportionately not so

much as the internal ones. Smear of juice expressed from peritoneal

glands shows large and small lymph cells in about proper proportions.

There are a few plasma cells. No granular cells.

Smear from bone marrow shows enormous number of premyelocytes and mast

cells. Polynuclears in their early stages are not numerous. Small

groups of lymphocytes, lightly packed together, noted here and there.

Blood smears unsatisfactory.

Microscopical.—Lung shows distended vesicles with considerable

congestion of septa and in some places red blood cells in alveoli.

Kidney.—Glomeruli contracted, relatively anemic; capsule negative;

epithelium throughout in state of granular degeneration probably

fatty; connective tissue not increased.

Intestines.—Show slight hyaline change in muscle fibres and nodular

degeneration and disappearance of protoplasm, leaving bare nuclei and

outline of the cells; submucosa loose; mucosa shows infiltration of

round and plasma cells, diapedesis, degeneration and desquamation of

epithelium. Section of ileum shows a hyperplasia of lymph follicles

with active centre in which large endothelial cells predominate. Small

swellings in submucosa consist of chronic granulation tissue, but

there is no foreign body and no evidence of preëxistence of a lymph

follicle.

Lymph nodes loosely arranged but in places solidly small lymphoid;

chords and sinuses contain chiefly small lymph cells in which are some

mast and plasma cells; follicles small and loose, and centres contain

chiefly large lymph and plasma cells; connective tissue not increased

yet there are some fibroblasts in follicles.

Spleen.—Shows almost entirely hemorrhagic pulp; blood destruction not

active; follicles large and made up of about equal mixture of small

lymph, plasma and large lymph cells; connective tissue prominent

probably because of excess of blood around it.

LOCAL HYPERPLASIAS.

In this group and touching the purely hyperplastic, come the

hypertrophies of the lymphadenoid tissue of the nasopharynx; this can be

disposed of by stating that no true chronic hypertrophies have been

seen. With most cases of gastroenteritis in ungulates, and many in

carnivores, there is a swelling and redness of the tonsillar region but

an exudative or necrotizing process does not occur.

THYMUS.

The thymus is rarely visible in our specimens but when found has usually

been normal. An increase in size and a decrease of consistency of this

organ is noted in marasmus (inanition) from failure of care of the young

by the parent, but so far as can be determined this has not been

adequate to cause tracheal compression. In a few cases of rachitis in

the canines, the organ is large and pale along with the rest of the

lymphatic system. In one of the tumors of the mediastinum to be

discussed, the suspicion arose that the growth originated in the thymus;

adenomata and sarcomata have been described in the lower animals.

TUBERCULOSIS.

Tuberculosis of the superficial lymph glands is rare as an independent

lesion in the lower animals. Dr. C. Y. White was fortunate in seeing a

monkey with a chain of fibrocaseous nodes in the cervical region, upon

which before death he offered the suggestion that it was of tuberculous

nature. In Primates almost all drainage glands exhibit some miliary or

caseous process. One monkey rejected upon the tuberculin test had what

was apparently a primary lesion in the glands at the tracheal

bifurcation. In the Ungulata, lymphatic tuberculosis assumes two forms,

the caseous and the cellular. The former is generally understood while

the latter is more uncommon. It is occasionally seen in the “fungous

tubercle” of cows, but we have seen it in deer and in another order,

Carnivora. In the latter, tuberculosis being uncommon, examples in the

lymph nodes were noted but twice, once caseous and once solid; this

latter was made up of firm, homogeneous yellow pink masses of glands in

the mediastinum, showing under the microscope solidly packed epithelioid

and giant cells.

Lymphatic tuberculosis in the birds is rare; only one case is recalled

(unfortunately record cannot be found) as small yellow, discrete firm

nodules in the mediastinum and neck. The minute picture was of a solid

arrangement of large vacuolated mono- and polynucleated cells which were

so packed with bacilli that the preparation could not be decolorized.

TUMORS.

The neoplastic enlargements are represented by a lymphosarcoma of the

mediastinum in a Dorcas Goat; there were secondary growths in the liver,

the kidney and several isolated lymph glands. Secondary growths from

original tumors not in the lymphatic system are curiously rare,

certainly much less frequent than is found in the human being. In

ninety-two tumors which are known to give metastases, only three

involved the lymphatic glands and only one of these could be considered

as involving nodes not in the ordinary drainage pathway.

THE SPLEEN.

The spleen is an organ whose exact position in the scheme of things

remains mystifying through the whole series of animals. Its functions

have been arrived at largely by exclusion, somewhat by conjecture and

speculation, while the acceptably proven duties are indeed few. Although

this is not the place to enter into a discussion of all the points at

issue concerning the anatomy and function of the organ, a few facts

might be mentioned of comparative and perhaps pathological value. While

the spleen has been looked upon always as the origin of blood cells in

the embryo, cases in man are on record where no spleen was discovered, a

condition suggesting that its absence is not incompatible with life;

that such is the case is obvious for experimental or therapeutic removal

of the organ is well known.

It was suggested by Virchow that at times the spleen assumes the duty of

the bone marrow and the swelling of the viscus in certain anemias seems

to support this statement. However, there is no physical relationship

between the size of the animal and that of the spleen, nor between the

available quantity of bone marrow, the obvious richness of circulating

blood and amount of lymphatic tissue. This is well shown in the water

mammals which have a great deal of blood in vessels and viscera yet

their spleen is relatively smaller than birds of somewhat comparable

size (the ostrich, for example). The Carnivora and Rodentia among the

mammals, have quite large spleens proportionately, while comparable

birds, Accipitres and Striges, have relatively small ones, and an

absolutely small amount of marrow.

Another anomalous example of the function of this tissue is found in the

hematopoiesis of birds. While there seems to be some evidence that in

the spleen and liver red blood cells may be formed, there is perhaps at

most times sufficient bone marrow to keep the blood cells at a proper

number. There is no inverse relation between the amount of bone marrow

and that of splenic bulk; that is in diving birds with their hollow

bones the latter is no greater than in gallinaceous birds which have

abundant marrow in all the skeleton.

It has been suggested that the spleen supplies an activator for

pancreatic ferments. This receives a sort of support from the greater

size of the organ in carnivores and smaller relative size in ungulates,

since in the former concentrations of digestive enzymes are more often

needed. Because of the greater excretion of iron in splenectomized

animals or those being starved, Fischer has thought that the spleen has

some power to metabolize this element; this receives some support from

the statements concerning the size of this organ in the carnivorous

orders. From experimental studies it appears that some relation exists

between the lymphocytes and resistance to implanted tumors. If one apply

this idea to the amount of lymphatic tissue and the incidence of

spontaneous new growths, it is found that no definite relationship is

discoverable either in terms of size of spleen or richness in lymphatic

nodes. Carnivores, rodents and marsupials show a high tumor incidence

and have a good lymphatic supply. Aves, on the other hand, with a poor

nodal apparatus and a variable splenic bulk, show many fewer tumors than

do the mammals. The mononuclears of avian blood rise normally as high as

60 per cent., of which 40–45 per cent. are of the small size.

The size of the spleen is subject to great variation not only within

orders but actually within genera; it even seems that one sometimes sees

two or three members of a species kept in the same enclosure, maybe with

the same disease, maybe without any obvious disease, yet with definite

variation in the size of the organ. This irregularity is recognized by

veterinarians (Hutyra and Marek) who ascribe it to some unknown disease,

past or present, and to normal variation. The lack of uniformity is seen

more clearly in birds than mammals. In the former it might be due at

times to low grade or inactive parasitism or, conjecturally, to toxins

from incorrect diet; we shall see later that infection and intoxication

seem to have a different effect. Some writers have mentioned the

possibility of an idiopathic splenomegaly (?), a condition associated in

youthful human beings, with anemia and lymphadenopathy, and occasionally

going over into a sort of leucemia. The existence of such a condition is

difficult to admit or deny; we have met nothing which could not be

aligned in some fairly well defined group. Birds have a relatively

larger spleen than mammals and in addition the organ seems to respond

more actively in infections or intoxications, since it may reach, under

active stimulation, a size ten times that of the normal organ.

ENLARGEMENTS OF SPLEEN.

Acute enlargements of the spleen, be they of congestive or

“inflammatory” nature are quite common among the lower animals, a fact

that is recognized in veterinary medicine. Congestions of the spleen are

most often seen during acute infections and diseases of the heart and

liver. The diagnosis has been made among mammals proportionately more

than in birds, 27 or 1.5 per cent. to 35 to 1 per cent.

REASON FOR CONGESTIVE ENLARGEMENTS.

Perhaps this is partly due to the circulatory anatomy since in the

former the arterial and venous supply is usually by one large vessel of

each kind, whereas in birds the splenic branch of the cœliac axis breaks

up into several small arteries and the venous return is accomplished by

numerous venules some of which reënter the posterior cava almost

directly, others joining with the mesenteric to form the portal; by this

arrangement a more elastic system is assured. The same condition is

found when analyzing the records of chronic passive congestion; in

eighteen recorded cases, fourteen were mammals and four birds. In these

cases the principal associated pathological lesions were pleural and

pulmonary in seven, cardiac in three, renal in three and hepatic in

four. While the anatomy of the splenic blood supply may help to explain

the small number of congestions in Aves, it will not answer for the

inflammations which occur in large numbers in this class; this will be

discussed in the following pages.

Hemorrhage and infarction of the spleen are not very common, there being

eleven of the former and ten of the latter and all occurring with the

same indication or history of infectious disease; in one case, an

opossum (_Didelphys virginiana_) an injury probably caused a massive

hemorrhage shaped like an infarct. It is, however, curious that of the

twenty-one cases only five occurred in birds, of which only one

hemorrhage was in the shape to which the term infarction is best

applied. There have been, as one might expect, a few cases of infected

infarction, with abscess. It is perhaps worth noting that no case of

hemorrhagic cyst or inspissated coagulum has been seen. Only one case of

rupture is recorded secondary to acute splenitis during an acute

septicemia.

INFLAMMATIONS.

It has been the practice at this laboratory to classify splenitis in

three ways, (1) acute diffuse splenitis—general congestion with perhaps

small hemorrhages, swelling but retention of general architecture and

with no undue prominence of the follicles; (2) follicular hyperplasia—

where this is the prominent gross and minute finding, the pulp being

less pronouncedly involved; (3) acute splenic tumor—where the organ is

greatly enlarged but with loss of the usual markings. Perhaps this

separation is not warranted upon a strict etiological basis, and yet as

we shall see it holds true fairly well in the toxic and infectious

lesions. Moreover, from the following list it is evident how the various

orders call upon the splenic tissue in disease.

TABLE 7.

_This Shows the Percentage of Various Forms of Splenitis in the Animals

Coming to Autopsy._

═════════════════╤═════════════════╤═════════════════╤═════════════════

│ Acute Diffuse │ Follicular │ Acute Splenic

│ Splenitis. Per │ Splenitis. Per │Tumor. Per cent.

│ cent. │ cent. │

─────────────────┼─────────────────┼─────────────────┼─────────────────

Carnivora │ 7.│ 3.│ 1.3

Primates │ 2.5│ 4.9│ 2.

Ungulata │ 2.4│ .3│ 1.2

Rodentia │ 2.6│ 4.7│ 1.

Marsupialia │ 9.2│ 3.│ 3.7

Pinnipedia │ _33._│ │

Proboscidea. │ _33._│ │

Edentata │ _12.5_│ │ _6.2_

│ │ │

Passeres │ 3.│ 3.│ 3.8

Psittaci │ 6.5│ 2.3│ 4.1

Anseres │ 5.2│ 7.2│ 5.2

Herodiones │ _1._│ _6._│ _2._

Galli │ 2.6│ 1.5│ 4.7

Struthiones │ _10._│ _10._│ _1._

Accipitres │ 7.5│ 3.7│ 1.6

Gaviæ │ │ │ _5._

Picariæ │ _4._│ │ _1.3_

Striges │ 6.8│ 3.4│

Fulicariæ │ _3._│ 6.│

Steganopodes │ │ _10._│

Columbæ │ .7│ .7│

─────────────────┴─────────────────┴─────────────────┴─────────────────

For the meaning of italics see foot note Table 1.

The points to draw from this chart are first the greater variety of

lesions seen in the birds, which apparently make greater use of the

organ in defence, and the preponderance of acute diffuse hyperplasias in

mammals. It is noteworthy that the Primates and Marsupialia show more of

the acute hypertrophy of the spleen going under the name of tumor. It

would be interesting and valuable to be able to discover exactly what

determines and constitutes the conditions usually termed hyperplasia and

inflammation of the spleen and an attempt was made in this direction by

tabulating the data from Table 7 in terms of each diagnosis, classifying

these latter also as infectious and toxic. The results of this effort

are not conclusive, and while they permit of some discussion of the

lesions, do not allow finished conclusions. The figures obtained by

study are not illuminating. One can state, however, that in infections,

either specific or not specific, more elements of the spleen were

engaged in the process than when the condition did not resemble a

communicable disease, but might be called toxic. Under the former

condition the diagnosis of splenitis or acute tumor predominated, while

under the latter follicular hyperplasia is more often recorded.

Anatomical alterations in these two groups are described in the

definition given in a previous paragraph and deserve no special

discussion except in so far as they concern the changes in the avian

splenic tumor when under magnification.

Microscopically there is a total loss of the relations in the acute

splenic tumor of birds, the chords and follicles being replaced by a

rather regularly arranged mass of small and large mononuclears, granular

cells of the circulating types and red blood cells; pigment always seems

increased. Endothelial cells do not take part in the general mass of the

organ but along lymph and blood vessels their bulk and number are

increased so that if the packing be not too dense one may find double

lines of these cells passing through the hyperplastic tissue. There is,

however, a group of seven cases (six birds) to which the term

endothelial hyperplasia in the spleen has been applied. All of them show

an unusual prominence of the vascular linings and of the follicular

centres and perivascular areas; besides this there is a moderate general

hyperplasia. An examination of the history and autopsy results in the

birds indicated that they had all suffered with some rather protracted

intoxication and showed a moderate anemia (four of the spleens were well

pigmented).

The more chronic changes of this organ, be they moderate or of a grade

to which one must apply the term fibrosis, are rather uncommon when one

considers the number of animals with prolonged infection, anemia,

skeletal diseases and hepatic cirrhoses; these are the conditions that

take a prominent place in the associated pathology and history. There is

no essential difference in the organ throughout the animal kingdom, and

one may find as far down as the struthious birds analogies to the

processes of domestic and human animals.

SPECIAL SUBJECTS—AMYLOID.

Amyloid changes in the spleen have occurred in the following orders:

Primates, Carnivora, Rodentia, Marsupialia, Passeres, Galli, Gaviæ, and

Anseres, fourteen cases in all. This infiltration is usually ascribed to

long continued suppuration or chronic infection, every one admitting,

however, that once in a great while a case is seen wherein no cause can

be discovered. In this laboratory we have a high percentage of cases

without adequate accompanying pathology so that we have called six of

the above cases primary or idiopathic. The gross appearance of the

spleen is in all these cases that of an enlarged, firm, homogeneous body

without the sago spots usually described for this change.

Microscopically the infiltration occurs first in the vessel walls,

thence spreading to the sinus walls and reticulum. Joest in discussing

this infiltration[19], states that it is comparatively rare among the

domestic animals, where it may appear under the usual conditions or as a

primary affection; it seems at times to follow unsuitable feeding.

According to this author, the “sago” type is more common than the

“bacony;” this has not been our experience. The most conspicuous example

is given here.

European Badger (_Meles meles_) Adult ♀ . Gradual failure for two

weeks.

DIAGNOSIS.—Amyloidosis. Chronic parenchymatous nephritis. Emphysema of

lungs.

Muscles atrophic; fat scanty. Heart is dilated and muscle is red-

brown. Aorta is jaundiced and there is a small patch of atheroma near

the anterior leaflet of aortic valve and about 5 mm. above it. Abdomen

contains a slight amount of clear fluid, no adhesions. Liver is normal

in size, smooth surface, sharp edges, firm consistency, yellow color.

The section surface is glistening, smooth and moist. The spleen is

very hard, greatly enlarged (25 × 6 × 2 cm.) and lies across the

abdomen over the intestines. It is pale red and very bacony. In iodin

the tissue stains a mahogany brown. The kidney is normal in size. (5½

x 3 cm.). The capsule is smooth and strips easily leaving a smooth,

yellow surface. Organ is firm. The section surface is glistening, has

a relatively narrowed cortex and relatively wide medulla. The

glomeruli are barely visible but stain a mahogany brown in iodin. The

adrenals are 12 × 10 × 4 mm. The cortex is wide, dull yellow and

regular. The zone beneath fades into the cortex although rather

abruptly. The centre of both glands is occupied by an irregular pale

yellow, sharply outlined nodule suggestive of solid medulla, tubercle

or tumor. The zone between cortex and this is gray, irregular and

firm. This is practically a normal figuration. The stomach is empty,

mucosa apparently normal. Intestines were not opened but serosa seems

normal; when opened after Kaiserling fixation they seem normal. The

pancreas is normal in size, firm and pale. Lymphatics of the mesentery

are slightly enlarged, soft, homogeneous pale yellow.

HISTOLOGICAL NOTES.—Lung seems somewhat atrophic and there are some

vesicular ruptures. One small patch of amyloid found in blood vessel

wall. Liver shows slight capillary congestion and granularity of

parenchyma. There is a marked blood vessel amyloid deposit not only in

interlobular spaces but in intralobular capillaries. Spleen, no trace

of splenic tissue recognizable in section. It is composed of more or

less eosin-staining material surrounding single, or small collections

of round or plasma cells. Kidney shows marked amyloidosis of glomeruli

and slight deposit in blood vessel walls and in the increased

connective tissue. There is a general moderate fibrosis; irregular

tubules; low epithelium and hyaline casts. Heart muscle fibres are

small and stain deeply. No amyloid in section. No pigmentation

although section is suggestive of brown atrophy. Adrenal is

practically negative. There seems to be slightly more connective

tissue than normal but parenchyma may be considered normal. At one

place in the cortex there are some structures of deep layer included

in vesicular layer. This seems like a structural malformation.

NECROSES.

Focal necroses of the spleen affecting chiefly follicular centres but

also chords, are not at all uncommon in avian spleens, especially where

parasitism occurs, not only with hemic protozoa and embryos, but also

with intestinal or visceral nematodes and trematodes.

SPLEEN IN ANEMIA.

The spleen in the anemias shows much less definite change than one would

expect. In the secondary form of anemia among mammals one finds a slight

excess of pigmentation and an occasional fibrosis but often the size of

the organ is recorded as normal. When the impoverished blood seems

secondary to skeletal degenerations there is a diffuse or follicular

enlargement. In the birds, on the other hand, there is nearly always

some grade of enlargement which is due in the well studied examples to a

richness of blood cells. There may be a slight increase in follicles,

but these bodies are usually small and solid. In two instances a

prominence of large endothelial cells was discovered. Pigment is seldom

increased, but it may be very excessive.

In the primary anemias little more than the above is to be found.

Fibrosis is more evident and perhaps pigmentation less so, but the

variations are more of degree than kind. The spleen in leucemia can only

be discussed upon the case already reported (_q. v._).

[Illustration:

FIG. 7.—EUROPEAN BADGER (MELES MELES). PRIMARY AMYLOIDOSIS. THE

ENORMOUSLY ENLARGED SPLEEN IS SEEN LYING ACROSS THE STOMACH BELOW

THE LIVER, WHICH ORGAN IS EXCEEDED IN SIZE BY IT.

]

SPLEEN IN HEPATIC FIBROSES.

The fibroses of the liver are not infrequently associated with some

enlargement of the organ under discussion. At this laboratory hepatic

cirrhoses are divided into Portal, Biliary, Fatty, Perilobular and

Vascular. By a study of the spleens in these cases a few facts have been

obtained. In mammalian portal cirrhoses there is usually a very moderate

but definite increase in the size of the spleen due to connective tissue

increase in the trabeculæ and reticulum, with very small compact

follicles. Among the birds the organ seldom shows more that a moderate

congestion and diffuse hyperplasia. In the mammalian biliary cirrhoses

there is almost without exception a definite enlargement due to fibrosis

and follicular hyperplasia. Among the birds the process is very far from

uniform, there being just as often no change, as a congestion and

hyperplasia, or as a mild fibrosis; it is notable, however, that

pigmentation is commonly met in this class. No noteworthy change is met

with in the spleen of fatty hepatic cirrhoses. We have no record of

cyanotic induration of the spleen accompanying a similar condition in

the liver. When the condition of perilobular hepatic fibrosis has been

met a distinct increase of the splenic pigment is usually found. In

reviewing the facts in this paragraph one is forced to the conclusion

that, with the exception of the frank infective cases, there is no

definite relation of the splenic changes to those in hepatic cirrhosis,

a fact made perhaps the more significant in view of the idea held in

some quarters that the primary change in this pathological process

occurs in the spleen.

PERISPLENITIS.

Perisplenitis of an acute or fibrosing variety as a part of peritonitis

or as the result of an injury to the splenic region, has been

encountered on numerous occasions and offers nothing worthy of comment,

but the so-called “sugar-icing” spleen, associated with perihepatitis

and general peritoneal thickening, and with an obscure relation to

tuberculosis has not been seen. As we shall learn later peritoneal or

massive intestinal tuberculosis is not common in the lower animals. A

diffuse fibrous thickening of a pearl gray glistening appearance, has

occurred in five monkeys harboring the Filaria gracilis in the

peritoneum.

TUBERCULOSIS.

In tuberculosis of this organ the capsule is almost invariably thickened

over the nodules, but not over the whole organ and rarely in the diffuse

variety. There is almost always, however, in this prolonged infectious

disease some reaction on the part of the spleen, particularly when

several other viscera are involved. In such cases a low grade of general

hyperplasia and fibrous tissue increase is found. This is especially

true in the Primates and Carnivora in long continued pulmonary

tuberculosis, and it is in this form that one does not often see

tuberculous lesions proper in the spleen itself. Tuberculosis of the

spleen is not very common in adult human beings and domesticated

animals, while in the young it is seen in a fairly high percentage of

cases. In the wild animals this organ seems much more susceptible to the

settling of tubercle bacilli as will be attested by the facts to be

cited, and yet there are some conspicuous exceptions to this statement.

Just why certain groups, or orders should show splenic tuberculosis very

frequently while others fail to do so is far from clear.

The appearance of the lesion is fairly comparable throughout the animal

kingdom, variations among the Aves being chiefly in the more frequent

occurrence of the diffuse tuberculous splenitis. Miliary, caseous and

conglomerate masses occur separately or together and without very

distinct relation to other pathological involvements.

The relative incidence of tuberculosis in the spleen is set forth in the

section devoted to this infection, but may be mentioned here in a

general way. The organ is about equally susceptible to the disease in

mammals and birds according to the figures, but the high percentage for

the former is due to the frequency with which tuberculosis is met in the

Primates. With this order deducted there is no doubt that the avian

spleen has a greater vulnerability for the tubercle bacillus than has

the mammalian organ. Rodentia as a mammalian order stand next to the

Primates, whereas the Carnivora and Ungulata relatively seldom show

splenic tuberculosis. Among the Aves one finds that Columbæ, Galli and

Accipitres have the highest splenic susceptibility, but beyond this one

hardly dare venture because of the irregularity in the number of

specimens seen at autopsy. Suffice it to say that a greater number of

cases of tuberculosis are seen in the spleen of the class for which the

intestinal origin of tuberculosis appears most important.

In the cases of actinomycosis and its congeners, such as the Kangaroo

maxillary mycosis, which we have seen at the Garden, no specific changes

have been seen in the spleen, unless a single or double nodule of the

same variety as the original focus may be considered specific. Such was

found in two cases, one a tapir with low grade inactive actinomycosis,

the other a kangaroo with maxillary streptothricosis. Two deer came to

autopsy with a gross picture suggestive of anthrax; no bacilli could be

found in the semifluid spleen, but a member of the hemorrhagic

septicemia group was found. The latter group of infections has been

fairly well represented, although not in epizoötic form, and the almost

invariable splenic change has been that already discussed as diffuse

splenitis. Three secondary tumors are recorded, two cancers and one

renal adenoma.

SECTION VI

THE RESPIRATORY SYSTEM AND ITS RELATED STRUCTURES

It is customary to divide the descriptions of normal and diseased

conditions of the upper entrance to the body into respiratory and

alimentary parts, the nose, nasopharynx and larynx belonging to the

former, the mouth, buccal cavity and pharynx to the latter. As a matter

of fact they can for most purposes be considered as the structures

contained in the anterior head and furthermore their pathological states

are more often followed by extensions into or implications of the

respiratory organs proper than of the alimentary tract. From a

comparative standpoint the incidence of specific infectious diseases and

of the involvement of accessory nasal sinuses present the most

interesting subjects. There are several infections, believed to be

specific, observed among domestic mammals and birds but their actual

individuality has hardly been unexceptionally proved. This refers to the

communicable rhinitis of cows, pigs, rabbits, and birds, especially

parrots, the follicular catarrh of horses, and croupous nasopharyngitis,

all of which have been ascribed to a particular virus, without finished

evidence in many instances. Some of these diagnoses doubtless cover or

are confused with the early symptoms and signs of the disease of protean

manifestations, distemper, and indeed the Bact. septicus and relatives

of the bird cholera organisms are reported as being responsible for

them. No intention of excluding well recognized entities like bird

diphtheria, foot-and-mouth disease or influenza, exists. I shall refer

below to small groups of epizoötics which do not conform strictly with

word pictures drawn by Hutyra and Marek, Moore, or Ward and Gallagher.

RHINITIS, SINUSITIS.

The nature of inflammations of the nasopharynx suggests at once that

there may be some anatomical reason for their distribution and

character. A general review of the anatomy of the mammalian and avian

nasopharynx reveals the relatively greater space in the former,

especially in the passage from the nose to the pharynx, and emphasizes

the exposure of the opening of the upper larynx in the bird, lying as it

does in the posterior part of the tongue and surrounded by the

constrictores glottidis. A dissection of the accessory nasal sinuses

exposes the relatively large size of these spaces in the lower mammals,

and the capacious openings into the nasal cavities.[20] In the Primates

and Lemures the anatomy more closely resembles that of man, the sinuses

being relatively smaller and the communicating passages narrower. In the

bird on the other hand, while the sinuses may be extensive in some they

are usually small, yet in all the communication with the turbinate area

is by a narrower slit or tortuous canal, frequently, as in Galli,

running from below upward into the maxillary sinuses. The extent of the

turbinate and the richness in mucosa is probably greater in all mammals

than in birds; certainly this seems true of Carnivora and Ungulata

_versus_ Accipitres and Galli.

If the seriousness of a rhinitis be dependent upon the extent of

involvement of the sinuses and the blocking up of their outlets it would

be expected that the variety of animal having the smallest drainage

channels would show the greatest evidence of these diseases. Our records

would indicate that 32 birds (.96 per cent. of the autopsies upon Aves)

had rhinitis whereas only 7 mammals (.39 per cent. of autopsies on this

class) presented the condition. Extension to the sinuses occurred in

only one-third of each of these figures, a complication which in turn

produced generalized infection more often in mammals than in birds as 4

is to 3. These figures are perhaps too small for conclusions but it

would seem that rhinitis occurs more often in birds with their small

sinuses and channels while sinusitis and general infection occur more

often in mammals with their large sinuses and extensive turbinate

apparatus. The most conspicuous orders represented are, in line of

numbers Anseres 12, Psittaci 7, Accipitres 5, Carnivora 3. Nine of the

twelve waterfowl were part of an epizoötic which will be discussed under

specific diseases.

Bacteriologically the mammalian cases that have been worked out were due

to _Streptococcus pyogenes_ in several instances, including the

generalized cases, and to a mixture of streptococci, golden

staphylococci and members of the colon-aerogenes group. In one case in a

tapir a member of the B. septicus group was found. Moulds were

discovered in three avian cases and filaria in one. No pentastomum or

œstrus has been discovered. In thirteen instances the lungs have been

involved, apparently secondary to the nasopharyngeal disease.

There have been two small outbreaks of an acute nonspecific infection—

that is not suggestive of cholera, psittacosis or infectious enteritis—

among the parrots in which during a short time 4 and 6 parrots died with

nasopharyngosinusitis as the prominent lesion. One outbreak was studied

bacteriologically without definite result. There was no uniform internal

pathology unless, in one outbreak, congestion of the cerebellum may be

mentioned. Fowl diphtheria and its associated condition from which a

satisfactory separation has not been accomplished, epithelioma

contagiosum, has happily given us little concern, so that it is not

possible to record any instructive facts upon its cause or differential

diagnosis. There was recorded in the 1911 Report of the Society the

occurrence of two fatal cases in cassowaries from which it was possible

to isolate the B. columbarum and one bird with the same clinical

appearances whose recovery seemed to be due to the use of human

diphtheria antitoxin. In light of more information and consideration of

the accepted variability of this disease, it is possible that this bird

may have recovered without the injections or with the use of normal

serum. Nowadays it is possible to obtain antiroup serum which is stated

by Blair of New York to be efficacious. The disease has been observed in

a wild turkey and an Abyssinian Ground Hornbill, beside the two

struthious birds mentioned above.

MYCOSIS.

Mycotic disease of the nasopharynx seldom restricts itself to this

cavity, usually extending by continuity to the esophagus, or by

inspiration to the lungs whence it spreads to the air sacs. This

condition of the upper passages has occurred here only in Psittaci and

Accipitres although it is reported by veterinarians as occurring in

Anseres and Struthiones. In the first order four birds were affected,

two showing extension to the esophagus and a like number having

pulmonary and serous membrane involvement. These cases were all due to

aspergillus whereas those next to be mentioned were caused by an oidium

close to the “albicans” variety. In four Mississippi kites the prominent

changes were found in the pharynx and esophagus down as far as the

proventricle with only a few rather trifling lesions in the nasal area.

Infiltrative and necrotizing processes characterized the action of the

oidium while that exerted by the aspergillus was more superficial and

extensive. In one case of a parrot the whole nasal cavity was completely

filled with a yellow gray exudate whereas the esophageal wall of the

kites was thoroughly infiltrated by a gray-brown, friable, necrotic

mass. Attempts at treatment were made in the case of the latter, using

potassium chlorate and saline solution on cotton swabs. The result was

entirely negative and the applications seemed to have no effect upon the

course of the infection.

There are on our records in addition to the above, several cases of

necrotizing processes about the head seeming to emanate from wounds to

the mucosa by foreign bodies, by decomposition of pieces of food in

crevices or by damage by masses too large to be swallowed. In the few

instances where we have tried bacteriology, no definite result has been

obtained unless the frequent occurrence of organisms bearing a

resemblance to Bact. necrophorus be important. This organism however may

be found in many necrotic processes in animals; I do not look upon it as

specific in the locations just cited.

Mammals as a class do not present many inflammatory conditions around

the anterior head, aside from the specific diseases like distemper (?),

actinomycosis, Kangaroo disease and the like. Monkeys occasionally have

acute coryza, which may indeed seem transmissible to others but it

seldom leads to any serious consequences and is untreated, except by

segregation. Tuberculous lesions are not recorded. There has been no

glossitis aside from lesions involving the pharynx. The tonsils have

been discussed under the lymphatic apparatus and it only need be

repeated here that inflammation and hypertrophy of these organs are

exceedingly rare. Specific or individual diseases of the salivary glands

are also rare although these organs may be involved by extension. This

general region is not often affected with tumor, unless the jaw be

included which bone is the seat of several tumors in antelopes and

opossums. Aside from these we have seen an epithelioma of the tongue in

a black bear (_Ursus americanus_).

LARYNX.

The larynx is an organ of fairly uniform construction through the

mammalian orders but is conspicuously different in the Aves where it is

double. The upper end of the trachea in the latter class is surmounted

by a cartilaginous box lying beneath the root of the tongue through

which an anteroposterior slit-like opening forms the glottis; there is

no epiglottis. This is only an air passage, the voice being made in the

syrinx or lower box which lies at the bifurcation of the trachea. The

structure of the upper box is quite simple with its lateral plates

controlled by the glossal muscles and two external retractors but the

syrinx is very complicated and variable in the different orders and even

in the same family. It possesses an internal and external set of muscles

and in some birds can be opened at one point to permit air to pass to

the cervical or thoracic air sacs. Detailed discussion of its anatomy is

hardly profitable since there is nothing peculiar about its diseases. On

one occasion only have we seen distinct pathological change—what was

probably an extension of mould disease from it to the cervical air sac.

It is involved in true tracheitis and bronchitis but even these are rare

in birds.

The larynx on the other hand is constantly reddened in cases of

pharyngitis and may be the seat of mould colonies. Edema of this

structure is, however, not very common, it being recorded but twice in

birds in association with nearby inflammation and five times in mammals;

in the latter cases three were of acute infectious nature, one was a

tumor and the other osteomalacia. It is common to find the laryngeal and

tracheal mucosa swollen and wet in chronic bone degenerations without

the condition being severe enough to call it edema.

LARYNGITIS.

Acute laryngitis of active catarrhal or purulent nature has been met

five times in mammals and twice in birds while more chronic lesions have

occurred only in the former, four times. Tuberculous laryngitis has been

observed in a cockatoo and a lemur; they are interesting enough to cite.

There are no cases recorded among monkeys despite the large number dying

from the disease; this implies of course that no suspicion of its

existence was had at postmortem but perhaps some would have been

detected had every larynx been subjected to microscopic section. A

citron-crested cockatoo was found when posted to have general miliary

tuberculosis. The bright red rim of the glottis attracted attention and

upon slitting open the organ, pinhead size, sharply outlined yellow

tubercles were found on both sides. A black and white lemur was killed

because of a positive tuberculin test. He was in good condition and

exhibited as his only lesions retropharyngeal lymph nodes with

precaseous miliary nodules and small miliary tubercles on the

epiglottis, true and false vocal chords and in the mucosa of the main

ventricle, each lesion being surrounded by a narrow sharply injected

zone. This seems like a recent double implantation since the

retropharyngeal glands probably do not drain toward or from the larynx.

The larynx has been the seat of only one tumor, a squamous cell cancer

in an Azara’s agouti. The tumor caused ulceration and edema of the whole

mucosa sufficient to produce fatal asphyxia.

The trachea is of relatively little comparative or pathological interest

aside from its inflammations which however are so closely associated

with bronchitis that they will be included under that heading. Perhaps

the most important condition of this tube is its infestation with

_Syngamus trachealis_ since this leads to inflammations not only of the

related mucosa but predisposes to pulmonary infection. The occurrence in

the Galli is well known but perhaps it is not so well recognized that

this worm occurs also in crows (Passeres) and swans and geese (Anseres).

For the diagnosis of this condition it is customarily stated that a

frothy mucus in the mouth is very suggestive; this is true in the cases

seen here but in addition a mucopurulent stomatitis is exceedingly

common and when the two are combined the picture is almost confirmatory.

Although worms are credited with considerable weight in the production

of pneumonia in Ungulata, they have only been seen once within the

tracheal tube.

THE BRONCHI.

The bronchi will be discussed as a separate part of the respiratory

system in so far as possible since they present a very decided

difference in anatomy between mammals and birds and because the

incidence of their disease is other than will be found for the lungs.

However, distinction has been made between changes in the grosser tubes

and those in the finer bronchioles, especially because capillary

bronchitis so-called is really a pneumonitis in which the mucosa of the

larger passages need not participate. The mammalian tubes are not really

greatly different in their construction, passing through ever smaller

branchings which give an increasing square area of tube capacity and

more extensive mucous surface. The avian main bronchus breaks up very

shortly after entering the lung into a varying number of spaces lined

with low epithelium lying upon a fibrous support and without cartilage.

These spaces then open into secondary air spaces of a size visible to

the naked eye which are in turn surrounded by microscopic alveoli. The

largest spaces, first mentioned, continue to grow smaller toward the

lower part of the lung where they usually communicate with one or other

of the various ostia of air sacs. Bronchial diseases in birds must

therefore be limited at the place where the bronchi lose the

cartilaginous rings since below this the surface functionates as

pulmonary tissue.

BRONCHITIS.

The accompanying list, Table 8, will show the distribution of bronchitis

not accompanying pneumonia or due to mycosis. It is striking that

carnivorous animals are more prone to bronchitis than any other order

(the struthious birds are too few to be important). There is a very

decided preponderance of mammalian cases over avian, there being not

only more cases but proportionately more orders affected. The character

of lesions in the mammals is nearly always catarrhopurulent or freely

purulent while ulcerative changes are not uncommon. Peribronchial

infiltrates are seldom found without some evidence of pneumonia; nor is

it common to meet the pale lines extending from bronchi between the

lobules, such as are seen in human streptococcal disease. Avian

bronchitis is usually hemorrhagic or catarrhal and with exceeding rarity

becoming purulent; when this occurs the cause is frequently found to be

tuberculosis or mycosis. Inflammation of the larger passages is nearly

always accompanied by pulmonary congestion, a serious condition in birds

as will be seen later. A few of these cases have been studied

bacteriologically with no definite result, nor have these cases occurred

in such groups that an epizoötic was suggested. Bact. avisepticum, Bact.

canisepticum, Bact. coli, Bact. aerogenes mucosum, and Ps. pyocyaneus,

Streptococcus hemolyticus and non-hemolyticus and staphylococci have

been found.

TABLE 8.

_Showing the Percentage Incidence of Bronchitis and of Parasites in the

Autopsies upon the Various Orders._

════════════╤═══════════════════╤═══════════════════╤═══════════════════

Orders │ Simple Bronchitis │ Verminous │Inactive Parasites

│ │ Bronchitis and │of Lung (Encysted)

│ │ Pneumonitis │ &c.

────────────┼─────────┬─────────┼─────────┬─────────┼─────────┬─────────

„ │ Cases │Per cent.│ Cases │Per cent.│ Cases │Per cent.

────────────┼─────────┼─────────┼─────────┼─────────┼─────────┼─────────

Primates │ 7│ 1.4│ 3│ .6│ 5│ 1.

Lemures │ │ │ │ │ 1│ 1.2

Carnivora │ 14│ 2.9│ 8│ 1.6│ 8│ 1.6

Insectivora │ │ │ │ │ │

Chiroptera │ │ │ │ │ │

Rodentia │ │ │ 2│ 1.│ │

Ungulata │ 5│ 1.3│ 2│ .5│ 10│ 2.7

Proboscidea │ │ │ │ │ │

Hyracoidea │ │ │ │ │ │

Edentata │ │ │ │ │ 2│ _12.5_

Marsupialia │ 3│ 1.7│ 2│ 1.1│ 3│ 1.7

Monotremata │ │ │ │ │ │

│ │ │ │ │ │

Passeres │ 4│ .29│ 7│ .5│ 2│ .16

Picariæ │ │ │ │ │ │

Striges │ │ │ │ │ │

Psittaci │ 4│ .58│ │ │ │

Accipitres │ 1│ .5│ │ │ │

Columbæ │ │ │ │ │ │

Galli │ │ │ 1│ .3│ │

Hemipodii │ │ │ │ │ │

Fulicariæ │ │ │ │ │ │

Alectorides │ │ │ │ │ │

Limicolæ │ │ │ │ │ │

Gaviæ │ │ │ │ │ │

Impennes │ │ │ │ │ │

Steganopodes│ │ │ │ │ │

Herodiones │ 1│ 1.│ │ │ 1│ 1.

Odontoglossæ│ │ │ │ │ │

Palamedes │ │ │ │ │ │

Anseres │ 2│ .67│ 3│ 1.│ │

Struthiones │ 1│ _3.3_│ │ │ │

────────────┴─────────┴─────────┴─────────┴─────────┴─────────┴─────────

For meaning of italics see footnote Table 1.

A review of the active verminous lesions of the bronchi and the

pneumonitis to which parasites lead, shows again the highest number

among the Carnivora, with negligible percentages among the Aves. The

forms concerned are, when determined, ascarides, strongylus, hepaticola,

fasciolopsis, cytoleichus, pneumonyssus and paragonimus; these will be

discussed later. The lesions in the bronchi are mucocatarrhal or

hypertrophic; occasionally actual ulcerations are seen. What is more

important however is the peribronchitis leading to interstitial

pneumonitis and to bronchiectasis of the smaller bronchi, or to areas of

atelectasis by total occlusion of some small air passage. This pathology

is fairly well recognized among veterinary pathologists but there are

two points which seem worthy of special emphasis, namely, the relative

mildness of the changes in the larger bronchi and the importance of the

worms as causes of pneumonia. In regard to the first it can be pointed

out that the trachea and its branches need not be altered at all while

the middle sized bronchi present a mottling of small recent congestion

with pigmentations from old hemorrhages, together with slight

unevennesses of the surface. Small bronchi on the other hand are the

seat of ulcerative internal processes and quite marked peribronchitis,

as indicated by round and connected tissue nuclei or perhaps polynuclear

increase under active acute inflammation; it is in the latter case that

acute pneumonitis is present.

To what extent do the parasites predispose to pneumonia? Compare for

this purpose the two columns of Table 8 showing active and inactive

pulmonary parasitism. In Rodentia and Galli alone do we note that active

parasitism is effective, there being no passive cases. In all the other

orders, animal invaders of the lung are more often encountered as

quiescent or encapsulated bodies, therefore as findings incidental to

the autopsy and perhaps not concerned in the cause of death. In Ungulata

the inactive parasitisms are five times as frequent as the active

inflammatory lesions. It might be added that the list is made up of

cases wherein we saw parasites whether determined or not, an explanation

of the apparently small number of cases; there were many more in which

such invaders were suspected but not found and therefore excluded.

BRONCHIECTASIS.

Bronchiectasis affecting the smallest tubes, or bronchiolectasis, is not

at all uncommon in verminous pneumonitis and is explained as due to the

degeneration of the wall, the surrounding progressive ulceration, to

accumulation of inspired air and its retention by the obstruction. There

is described a generalized bronchiolectasis, chiefly in young human

beings, due to a destructive bronchiolitis; this has not been seen.

Non-verminous bronchiectasis of the middle sized bronchi such as is seen

in human chronic bronchitis, simple or tuberculous, is quite uncommon.

Widening of the bronchial lumen may be divided, as I see its

pathogenesis, into (a) that due to congenital weakness of the walls, (b)

that due to obstruction permitting air to pass into but not out of a

bronchus because of a ball-valve obstruction or weakness of expiratory

power, (c) that due to external pressure by tumors or distortion by

fibrous tissue either within the lung or pleura and (d) that due to

inflammatory weakening of walls, augmented by loss of supporting

pulmonary tension, accummulation of secretion and the dilating effect of

inspiration preparatory to and incidental to coughing. How important the

last three auxiliary factors may be in the cases explicable under a, b,

c, can easily be speculated upon and may vary in different cases.

Bronchiectasis is reasonably common with pulmonary diseases of man,

particularly of chronic character, but is certainly not frequent among

animals. Under the first group (a) we can record one case, a Siberian

tiger which died of enteritis and its complications to which were added

a mild inactive bronchitis and a bronchiectasis of diffuse distribution.

The lungs were irregular in shape, dull, gray-red in color and gave a

variable boggy and vesicular sensation to the fingers. On opening the

lung, dilatations of the bronchi were found, affecting chiefly the

larger secondaries but apparently not the bronchioles. Parasites were

not found nor were inflammatory reactions apparently adequate to explain

the distentions, so that we looked upon this case as congenital. Cases

coming under the headings b and c are not recorded. Inflammation almost

certainly represents the most important single factor in the

pathogenesis of this lesion and could be demonstrated in two cases, a

Clouded Leopard (_Felis nebulosa_) and a Red River Hog (_Potamochærus

porcus_). While I feel that parasites probably laid the foundation for

the dilatations in these cases, none were found after, in one case at

least, a very thorough search, although in the second animal a single

cyst of _Cysticercus tenuicollis_ was found in the peritoneum. In both

animals there was a low grade interstitial pneumonitis and

peribronchitis with dilatations of the middle sized and end bronchi,

these being supplied with thick walls but containing very scanty

secretion.

We have on record chronic ulcerative pulmonary tuberculosis in six

primates, two carnivores and nine ungulates. It is highly probable that

among this number some cases of ulcerative bronchiectasis occurred but

if so they were not conspicuous enough to mention in the diagnosis and

in only two protocols do I find a discussion thereof, once in a monkey

and once in a carnivore. All the cases of our records were diffuse

ectasias, fusiform, or irregular and none of the distinct saccular

variety.

From the foregoing facts it would seem that in human cases more weight

should be laid to the effect of the dilating power of coughing and its

preparatory exertions. While I am aware that the comparative incidence

of human and lower animal bronchiectasis cannot be based upon the meager

figures at our command, these dilatations certainly can be expected in a

general autopsy service more in man than in lower animals. Chronic

bronchitis is relatively rare, aside from the verminous varieties. I

have seen little retained exudate in the bronchi, probably because

quadrupeds seem with ease to raise and swallow the secretions. Nor do

animals give vent to paroxysms of coughing such as the human being feels

forced to do. Suggestive deductions from these points are that

inflammation is the principal factor in acquired bronchiectasis and that

the retention of secretion with violent inspiratory efforts are potent

in man for the dilatation of the tubes.

THE LUNGS.

The essential respiratory organ of the animal body, the lung, is all

through this kingdom a structure intended to expose the blood to free or

combined atmosphere in order to permit gaseous interchange, therefore

being arranged so that there is a close apposition of the two factors,

separated only by such cells and membranes as may be necessary to

protect the circulation; perhaps these anatomical elements possess at

the same time some vital force to further the exchange of useful and

useless matter. In the two classes under discussion there is no

difference whatsoever in the primary factors of respiration albeit some

variations exist in reference to oxygen and carbon dioxide interchange,

moisture of the air, and the physics of inspiration and expiration. The

chemical variables have in our limited knowledge of comparative

physiology apparently little effect upon morbid anatomy but it is

probable that some pathology may be in part explained on physical

grounds.

The mammalian respiratory box is a relatively elastic affair, but

collapsed at the end of expiration which is largely a passive or recoil

process. The avian thorax is believed to be normally a tensely distended

space from which air is expelled by pressure of the pectoral contraction

upon the broad sternum driving the latter back upon the air sacs which

in turn drives it from the lungs. Also by this means, air is distributed

through the bones and air spaces, a measure necessary in flight,

especially in a head wind when tracheal inspiration is said to be

suspended at times. The communications of the lungs, air sacs and bones

make it possible for birds to breathe internally when the trachea is

closed and externally as well if a bone be opened. The balance of air

pressure in the lungs and related spaces is dependent upon the patency

of the ostia communicating between the bronchial ends and the air sacs,

from which the bony cavities obtain their supply. Should all these be

closed there is first a standstill of current and a limitation of the

respiration of the lungs. Fortunately it is extremely rare that this

occurs for it is obvious that it is incompatible with flight, and with

life indeed. The principal effect upon the lungs of obstruction to the

passages seems to be expressed in congestion but in how far this is due

actually to the closure of foramina and how far to the cause of

obstruction is sometimes difficult to evaluate. It should be remembered

that the air sacs are usually looked upon as mucous surfaces continuous

with the bronchial wall, there being a deep layer to each membrane

possibly continuous with the serous membranes. In mould disease of the

lungs there is very commonly a colony lying in the ostium supplying the

anterior, lateral and posterolateral cavities.

The lungs in birds are not free as in mammals, being fitted into the

troughs made by the anterior ridges of the ribs, to the serous covering

of which they are lightly attached by delicate fibres running between

the two. This more or less definite fixation, together with the pressure

of the air in the sacs give the free play of the lungs a limited

excursion. They are naturally very elastic by reason of a good supply of

elastic fibers and large air spaces, a condition aided by their

attachments to the supports of the diaphragm and to the insertions of

the air sac walls. Notwithstanding this elasticity and the great

capacity of the organ for blood, it seems as if congestion of the lungs

is a very serious matter, since from the foregoing review of anatomy,

accommodation of excess blood and any consolidation must be difficult.

As a matter of fact the mere excess of blood known as active congestion

seems able to kill small varieties.

CONGESTION OF LUNGS.

Birds of flight seem to have little resistance to this condition and

often it is the only diagnosis one can make at autopsy. The causes of

this condition include exposure, dust, gorging (?), indigestion,

enteritis and infection in birds while in mammals acute gastrointestinal

disease stands out as the most prominent accompaniment. To what extent

dust and exposure operate I do not see, although they are frequently

mentioned as causes. The overfilling of the crop, esophagus and

proventricle, the turgescence incident to gastric indigestion or the

pressure of foreign bodies in large amount are supposed to operate by

exerting pressure on the anterolateral air sacs with closure of their

ostia and also by right lateral torsion of the heart with twisting of

the very delicate pulmonary veins.

I have sought to show that protozoa or embryo nematodes in the blood

might embarrass the lungs to a state of congestion, a thought suggested

by some findings in the London Gardens, but only about ten per cent. of

our cases of hemic parasitism are accompanied by it.

The incidence of congestion of the lungs not due to stasis as from

cardiac diseases, is 2.4 per cent. in mammalian autopsies, in only 7 per

cent. of which figure did it represent the principal morbid anatomy,

whereas in birds it occurred to the extent of 7.6 per cent. of

postmortems, in 17 per cent. of which it was the sole or principal cause

of death. This seems to bear out the feature of delicacy of the

pulmonary vascular mechanism in these latter animals. This condition

seems to be indicated by simple dyspnœa in birds, relief for which has

occasionally been afforded by removal from the exhibition cages and

protection separately in a warm dry room; this is partly hypothetical of

course and congestion is to be looked upon as serious, particularly in

passerine birds.

PNEUMONIA.

Pneumonia as a clinical disease is a relatively uncommon, although quite

serious sporadic condition in animals. However accompanying the

specific, more or less epizoötic diseases such as influenza, distemper

and the choleras it may be a frequent and quite pronounced complicating

feature of the case. Pneumonia _per se_ has exacted a reasonable toll in

this Garden but unfortunately recognition being impracticable, diagnosis

and treatment have not progressed. Nor has it been practicable to group

our cases pathologically because of the lack of history and the

difficulty of making bacteriological observations at many autopsies.

Fortunately we have had practically no epizoötic pneumonias, an

experience shared with other gardens judging by their published reports.

Etiologically, and of course this applies to non-verminous, non-mycotic

and non-tuberculous cases, the pneumococcus has stood out prominently as

a cause with a few additional cases due to the streptococcus and the

Bact. aerogenes mucosum group; London reports four cases in monkeys due

to the Friedlander bacillus. Some time ago Doctor Weidman subjected our

pneumonias to an analysis and was able to show that there is no

parallelism between the seasonal incidence of pneumonia in man and

animals, rather indeed that the Garden is more apt to have a greater

number of cases in the summer, a sort of “closed season” for man. This I

am inclined to interpret as connected with the larger number of visitors

during that season. Doctor Weidman was further able to show that the

only real examples of lobar fibrinous pneumonia strictly comparable to

the human infection occurred in the Primates. I have uncovered one in a

lemur and one in a carnivore. The pneumococcus has been far and away the

greatest producer of our pneumonias, in two typed cases being of the IV

variety. There will be given below a summary of the pathological types

of pneumonia encountered, to be followed by some notes upon the

principal gross and minute anatomy in special orders. Table 9 will show

the numerical distribution of types among the orders. All the principal

mammalian orders are represented while the birds seem relatively less

susceptible to the disease and, except the Passeres, show a trifling

incidence.

TABLE 9.

_Showing the Number of Cases of the Various Forms of Pneumonia Found in Each

of the Orders._

════════════╤═════════╤═════════╤═══════╤══════╤══════════╤═══════╤═══════════

│Fibrinous│Catarrhal│ Acute │Septic│Hypostatic│Chronic│Pleurogenic

│ Lobar │ │Inter- │ │ │Inter- │

│ │ │stitial│ │ │stitial│

────────────┼─────────┼─────────┼───────┼──────┼──────────┼───────┼───────────

Primates │ 4│ 22│ 2│ 1│ 1│ 2│ 2

Lemures │ 1│ 3│ │ │ │ │

Carnivora │ 1│ 34│ │ 4│ │ 1│

Insectivora │ │ │ │ │ │ │

Chiroptera │ │ │ │ │ │ │

Rodentia │ │ 6│ │ 3│ │ │

Ungulata │ │ 14│ │ 5│ 1│ 1│

Proboscidea │ │ 1│ │ │ │ │

Hyracoidea │ │ │ │ │ │ │

Edentata │ │ 1│ │ │ │ │

Marsupialia │ │ 13│ 1│ │ 1│ │

Monotremata │ │ │ │ │ │ │

│ │ │ │ │ │ │

Passeres │ 1│ 59│ 2│ 2│ │ │

Picariæ │ │ │ │ │ │ │ 1

Striges │ │ 3│ │ │ │ │ 1

Psittaci │ 1│ 15│ │ │ │ 1│

Accipitres │ │ 1│ │ │ │ │

Columbæ │ │ 2│ │ │ │ │

Galli │ │ 2│ │ │ │ │

Hemopodii │ │ │ │ │ │ │

Fulicariæ │ │ 1│ │ │ │ │

Alectorides │ │ │ │ │ │ │

Limicolæ │ │ │ │ │ │ │

Gaviæ │ │ │ │ │ │ │

Impennes │ │ │ │ │ │ │

Steganopodes│ │ │ │ │ │ │

Herodiones │ 1│ │ │ │ │ │

Odontoglossæ│ │ │ │ │ │ │

Palamedes │ │ │ │ │ │ │

Anseres │ 1│ │ │ │ │ │

Struthiones │ │ │ │ │ │ │

────────────┴─────────┴─────────┴───────┴──────┴──────────┴───────┴───────────

Primates present a definite group of variations from the other orders,

notably in having four clear cases of lobar fibrinous pneumonia, and in

certain histological findings. In reference to the lobar cases, a review

of their history does not indicate that any might have been surely

diagnosed by their symptoms, and only possibly by signs in one case

during the stage of red hepatization; unfortunately no temperature

records are at hand. In one case it was possible to see a group of

alveoli with the fibrin collected in a strand which, according to

classical description, passes through the septum to the adjoining

alveolus.

There were two cases, a Chimpanzee (_Pan niger_) and a Galago (_Galago

maholi_) with a microscopical picture suggestive of those we met in the

influenza epidemic, and indeed the lung of the former resembles grossly

the lung of influenza pneumonia. The spotty areas of watery purple color

correspond under magnification to celluloedematous semisolid sections

showing a sanguineous exudate, few polynuclear cells and many swollen

epithelia. The microscopic picture of the bronchocatarrhal pneumonias

shows conspicuously thickened septa decidedly wider than one is

accustomed to see in human cases and apparently due more to round cell

infiltration than to congestion or polynuclear increase.

Bronchopneumonia or capillary bronchitis with zones of cellular edema in

the vicinity is a rather usual picture in the deaths from degenerative

bone disease. It cannot be said that there is anything very peculiar

about it, although a frequent note met in the autopsies describes spotty

areas of hemorrhage and nearby atelectasis.

The case of lobar pneumonia found in a ring tailed lemur (_Lemur catta_)

showed very delicate fibrinous reticulum and relatively few cells in the

exudate, a picture apparently due in part to beginning resolution since

the whole upper left lobe was in a stage of gray hepatization.

The peculiarity of the Carnivora seems to lie in the reaction of the

epithelia, these cells being quite large, swollen and occasionally much

vacuolated. Such a picture was most pronounced in the terminal

bronchitic pneumonias in cases which might be called distemper. Many

instances of pseudolobar catarrhal or bronchopneumonia are recorded but

we also observed the fibrinous lobar form at the stage of red

hepatization in a Texas skunk (_Mephitis mesomelas_). Concerning the

orders Rodentia and Edentata no especial notes seem necessary for their

inflammatory reactions are essentially like the others in that

epithelial cells are much swollen and prominent.

Pneumonias of Ungulata are well known to pathology and offer in

causation and microscopy little that is peculiar. It might be emphasized

however that the gross appearance of the bronchocatarrhal variety

closely simulates that of lobar pneumonia, therefore to be called a

pseudolobar form, in that extension to various parts of a lobe seems to

occur. Moreover in the bronchitic varieties associated with enteritis,

with or without infectious foci in the pharynx or larynx, there may be

two or even three stages of the pneumonitic process in one lung or lobe.

It seems that this pseudolobar appearance occurs definitely more often

in ungulates than in the other orders.

[Illustration:

FIG. 8.—NORMAL AVIAN PRIMARY AND SECONDARY ALVEOLI. NOTE THE DELICACY

OF THE SEPTAL PROLONGATIONS THAT BOUND THE PRIMARY ALVEOLI, ALL OF

WHICH ARE WIDELY OPEN.

]

[Illustration:

FIG. 9.—EARLY BRONCHOPNEUMONIA OF SUPERFICIAL ORIGIN. NOTE SOME LITTLE

EXUDATE IN SECONDARY ALVEOLUS. WIDE SWOLLEN SEPTA AND BOTH ALVEOLI

REDUCED IN SIZE.

]

Marsupialia offer two rather easily grouped classes of bronchopneumonia—

one associated with enteritis and one secondary to “Kangaroo disease” of

the jaw; they differ in microscopy correspondingly. The simple

bronchitic and peribronchitic infiltrate and superficial exudate

occurring with enteritis or with a general infection is relatively

diffuse, giving in some instances the impression of an interstitial

process and showing notably swollen septa; there may be fibrin but this

is exceptional and scanty. When mycosis of the jaw has been the origin

or occasion of the infection the picture is that of frank aspiration

pneumonia, therefore more like a septic infarct. However the amount of

fibrin is sometimes very great and whole alveoli will be filled with it,

perhaps accompanied by red cells, polynuclears and epithelia. Epithelial

cells however play a small part in the minute anatomy. Hemorrhage and

edema are prominent but true abscess formation and gangrene are not.

Possibly the animals die too soon for the latter to develop.

Pneumonia in Aves aside from that due to moulds is apparently much less

common than among the Mammalia, one order only, the Passeres, showing an

incidence comparable to the important orders of the latter class. The

other orders, and this applies particularly to those of which we have an

adequate number, are quite insusceptible to simple pneumonia, none of

them showing over two per cent. There are listed for Aves three

instances of lobar fibrinous pneumonia. These cases can be described

together since in all the findings were about the same. A whole lung or

goodly portion thereof was uniformly involved in a red or gray

consolidation of rather fine granular character which on section study

seemed to be made up of the same lesion all over, with fibrin a

prominent part of the exudate. The coagula were largely within the

secondary alveoli but the primaries also contained it. The microscopic

section may not have represented the process at all places, and since

the arrangement of fibrin is similar in definitely catarrhal lesions,

these may of course have been instances of pseudolobar pneumonia.

Our data are too few to draw any conclusions as to the behavior of the

various orders but one note may be permitted. The passerine birds have a

great tendency to dense cellular infiltrates while parrots show more

coagulative or fluid exudates.

PRODUCTION OF INSULAR PNEUMONIA IN BIRDS.

Insular consolidations in which catarrhal and infiltrative processes are

prominent, the bronchopneumonias, seem to arise in two ways. One course

of events apparently follows infection _via_ the bronchial mucosa, the

other _via_ the blood stream and a study of the resulting lesions may

help toward an understanding of the development of pneumonia in man.

When infection unquestionably has been superficial, that is _via_ the

bronchus, the first thing to happen is a swelling of the septal

prolongations dividing the primary alveoli and an extension of their

ends farther into the secondary alveoli with the result that the inlet

to the primary air sacs is narrowed and the space in the secondaries is

reduced. Upon the surfaces there then develops the usual catarrhal

exudate while in the deeper parts marked congestion makes its

appearance. Fibrin may develop and be mixed with the cells both in the

larger and smaller alveoli but it is more evident in the former. (Figs.

8, 9, 10.)

[Illustration:

FIG. 10.—LATER BRONCHOPNEUMONIA OF SUPERFICIAL ORIGIN. NOTE GREATER

EXUDATE, GREATER SWELLING OF SEPTA. PRIMARY ALVEOLI PRACTICALLY ALL

CLOSED. MUCH OF LUNG HAS BECOME CONSOLIDATED.

]

[Illustration:

FIG. 11.—INSULAR PNEUMONIA, BEGINNING AS CELLULAR INFILTRATION OF

DEEPER PARTS OF SEPTA AND OF INTERSTITIAL TISSUE. FOUR AREAS OF

DENSE AIRLESS CONSOLIDATION. ALL SECONDARY AND MANY PRIMARY ALVEOLI

WIDELY OPEN.

]

The other process by which insular pneumonia develops seems to begin in

the septa of the smaller alveoli and in the perivascular areas. This has

been looked upon as hematogenic or pleurogenic. The first change occurs

in the surroundings of the primary alveoli where there appears a

richness of nuclei, of round, moderately well stained character, among

which one may see a few granular and red blood cells. Soon the epithelia

of adjacent alveoli increase in number and a fibrinocellular exudate

appears, at first probably in the smaller sacs. However when the lesion

is intensive the course of events must be rapid for the identity of a

group of primary alveoli is soon lost and the exudate may extend to the

larger air space. (Fig. 11) In severe or late cases a decision as to the

course of origin is often impossible. The most instructive point of this

part of the study is the closing of primary alveoli by the swelling of

their septal ends and the early occlusion of the secondary alveolus by a

catarrhofibrinous or even pus-like material. It is quite possible that a

similar course of events transpires in the pathogenesis of human

pneumonia, the superficial avian form being comparable to the aspiration

form, the interstitial form comparable to the septicemic variety.

ABSCESS AND GANGRENE OF LUNG.

Abscess and gangrene of the lung are degenerative processes dependent

upon embolism, or inspiration of infective matter and it is usually

assumed that gangrene succeeds upon abscess when the blood or air supply

of a part of the pulmonary tissue has been obstructed mechanically or by

inflammation. A review of our material adds little to the etiology or

pathogenesis of these two lesions, well recognized as they are by

veterinarians. As opposed to human beings, lower animals probably suffer

more from them, for an explanation of which one can probably look to the

B. necrosis or necrophorus, an organism quite common in feed, and

acknowledged to be of great importance as a secondary invader during

specific infectious diseases. It has been found in embolic abscesses and

in the organs in calf diphtheria and similar other conditions. It has

been cultivated here twice, once from a lung abscess, once from Kangaroo

disease. It doubtless occurs in human necrotizing processes but is

seldom emphasized or even heard about; possibly none is due to it or its

congeners.

TABLE 10.

_Table giving Analysis of 20 Mammalian and 3 Avian Cases of Abscess and

Gangrene of the Lung_

════════════╤═══════════════╤════════════════╤════════

Animal │ Causative │ Pneumonia, │Abscess

│condition upper│septic or other │ or

│ respiratory │ │Gangrene

│ tract │ │

────────────┼───────────────┼────────────────┼────────

Sooty │Negative │Catarrhal │Gangrene

Mangabey │ │pneumonia │

Cercocebus │ │ │

fuliginosus │ │ │

│ │ │

Rhesus │Negative │Septic from │Abscess

Macaque │ │suppurating │

Macacus │ │gland │

rhesus │ │ │

Am. Wild Cat│Aspiration │ │Gangrene

Felis ruffus│vomitus from │ │

│violent │ │

│gastroenteritis│ │

│ │ │

│ │ │

│ │ │

Puma Felis │Acute purulent │No │Abscess

concolor │nasopharyngitis│ │and

│ │ │gangrene

│ │ │

│ │ │

Ichneumon │Negative │Sepsis, scalp │Abscess

Herpestes │ │wound │

mungo │ │ │

│ │ │

│ │ │

Raccoon │Negative │Pneumonia │Abscess

Procyon │ │followed by │

lotor │ │sepsis │

│ │ │

│ │ │

Skunk │Cellulitis face│Sepsis, very │Abscess

Mephitis │and neck │mild │

mephitica │ │ │

Puma Felis │Perforating │Secondary │Abscess

concolor │abscess around │terminal │

│jaw │pneumonia, │

│ │sepsis │

│ │ │

│ │ │

Porcupine │Negative │Enteritis, no │Abscess

Erethizon │ │special sepsis │

dorsatus │ │ │

│ │ │

│ │ │

│ │ │

Kangaroo Rat│Negative │Right sided │Abscess

Perodipus │ │bronchopneumonia│

richardsoni │ │ │

│ │ │

Squirrel │Abscess under │No │Abscess

Sciurus p. │eye and in │ │

carolinensis│masseter muscle│ │

│ │ │

│ │ │

│ │ │

Mule Deer. │Actinomycosis? │Arthritis. │Abscess

Mazama │nasopharynx │Myositis │and

hemionus │ │Tenosynovitis │gangrene

│ │ │

│ │ │

Axis Deer. │Negative │Negative │Abscess

Cervus axis │ │ │

│ │ │

│ │ │

│ │ │

│ │ │

│ │ │

│ │ │

Tapir. │Abscess of │Died from │Abscess

Tapirus │parotid │enteritis │

indicus │ │ │

│ │ │

│ │ │

│ │ │

Gazelle. │Negative │Sepsis from │Abscess

Gazella │ │infected wound │

isabella │ │ │

│ │ │

│ │ │

Kangaroo. │Negative │Catarrhal │Abscess

Macropus │ │pneumonia │and

rufus │ │ │gangrene

│ │ │

│ │ │

│ │ │

│ │ │

│ │ │

│ │ │

Kangaroo. │Kangaroo │Sepsis │Abscess

Macropus │mycosis of jaw │ │

rufus │ │ │

│ │ │

Kangaroo. │Kangaroo │ │Abscess

Macropus │mycosis of jaw │ │

giganteus │ │ │

│ │ │

Kangaroo. │Negative │Sepsis from │Abscess

Macropus │ │infected wound │

robustus │ │ │

Devil. │Negative │Negative sepsis │Abscess

Sarcophilus │ │ │

ursinus │ │ │

│ │ │

│ │ │

Crow. │Negative │Filaria in │Abscess

Gymnorhina │ │blood? │

leuconota │ │ │

Heron. Ardea│Negative │Negative │Abscess

tricolor │ │ │

ruficollis │ │ │

│ │ │

│ │ │

Goose. Anser│Syngamus in │Negative │Abscess

fabalis │trachea │ │

│ │ │

│ │ │

│ │ │

│ │ │

────────────┴───────────────┴────────────────┴────────

════════════╤═════════╤══════════════╤══════════════

Animal │Single or│ Position │ Bacteria

│Multiple │ │

│ │ │

│ │ │

────────────┼─────────┼──────────────┼──────────────

Sooty │Massive │Upper part │Streptothrix,

Mangabey │single │lower lobe and│necrosis

Cercocebus │ │adherent part │bacillus.

fuliginosus │ │upper lobes │

│ │left side │

Rhesus │Single │Occupied │

Macaque │ │nearly all │

Macacus │ │right middle │

rhesus │ │lobe │

Am. Wild Cat│Bilateral│Right middle │

Felis ruffus│ │lobe, left │

│ │lower lobe, │

│ │left bronchus │

│ │ruptured, │

│ │right middle │

│ │lobe ruptured │

Puma Felis │Bilateral│Right upper │Streptococcus

concolor │ │and left lower│pyogenes.

│ │lobe abscesses│

│ │biggest, right│

│ │middle also │

Ichneumon │Bilateral│Scattered │

Herpestes │ │small │

mungo │ │abscesses, │

│ │under pleura │

│ │especially │

Raccoon │Bilateral│Probably all │

Procyon │ │lobes, right │

lotor │ │middle │

│ │contains │

│ │largest │

Skunk │Single │Left lower │

Mephitis │ │lobe, single │

mephitica │ │small │

Puma Felis │Bilateral│Numerous small│

concolor │ │abscesses, │

│ │irregularly │

│ │scattered │

│ │through both │

│ │lungs │

Porcupine │Bilateral│Multiple small│

Erethizon │ │scattered. │

dorsatus │ │Parasitic? No │

│ │notes │

│ │parasites or │

│ │bacteria │

Kangaroo Rat│Single │Left lower │

Perodipus │ │lobe, small │

richardsoni │ │abscess, │

│ │record scanty │

Squirrel │Multiple │Left lung │

Sciurus p. │ │scattered, │

carolinensis│ │small │

│ │abscesses, │

│ │parasites not │

│ │seen │

Mule Deer. │Bilateral│Scattered both│

Mazama │ │lobes under │

hemionus │ │pleura, upper │

│ │right inferior│

│ │tip gangrenous│

Axis Deer. │Single │Apparently │Streptothrix.

Cervus axis │ │primary │

│ │streptothrix, │

│ │abscess in │

│ │cardiac tip of│

│ │upper lobe │

│ │with extension│

│ │toward hilum │

Tapir. │Bilateral│Multiple │Staphylococci.

Tapirus │ │subpleural pus│

indicus │ │pockets, │

│ │surrounded by │

│ │catarrhal │

│ │pneumonia │

Gazelle. │Bilateral│Multiple │

Gazella │ │subpleural and│

isabella │ │internal, both│

│ │lungs about │

│ │the same │

Kangaroo. │Double │Lower middle │Pneumococci

Macropus │left │left lobes, │streptothrix.

rufus │ │seat of a │

│ │ruptured │

│ │gangrene │

│ │surrounded by │

│ │pneumonia, │

│ │right lung │

│ │pneumonic │

Kangaroo. │Bilateral│More on right │Streptothrix,

Macropus │ │side, sharply │cocci.

rufus │ │outlined │

│ │abscesses │

Kangaroo. │Single │Abscess and │Streptothrix

Macropus │ │atelectasis, │

giganteus │ │right middle │

│ │lobe │

Kangaroo. │Single │Lower right │

Macropus │ │lobe │

robustus │ │ │

Devil. │Multiple │Largest middle│Probably

Sarcophilus │ │of right lung,│streptothrix.

ursinus │ │many small │

│ │scattered │

│ │abscesses. │

Crow. │Multiple │Scattered tiny│

Gymnorhina │ │abscesses, no │

leuconota │ │worms seen │

Heron. Ardea│Single │Upper pole, │

tricolor │ │right lung, no│

ruficollis │ │apparent │

│ │antecedent │

│ │cause │

Goose. Anser│Single │Lower half │

fabalis │ │right lung │

│ │occupied by │

│ │abscess, which│

│ │has penetrated│

│ │air sac │

────────────┴─────────┴──────────────┴──────────────

The distribution of abscess and gangrene in the lungs in terms of the

antecedent disease, therefore its causation, may however be of interest.

The lower animals move more in the horizontal position, they seldom

cough, they are subject to several different diseases with principal

lesions in the anterior head (diphtheria, actinomycosis, etc.) but not

to chronic lymphatic infection, they push their snouts into all kinds of

filth thereby probably taking into the nose and throat many objects

which can find their way to the bronchi, and finally they are not

subjected to various instrumental operative procedures when they chance

to have a focus of pathology in the nasopharynx. For these reasons the

position of abscess and its sequels may be instructive. It has recently

been stated that abscesses of the lung in human beings following

anesthesia for infections of the upper respiratory tract, occur most

often in the upper parts of the lung whereas those following pneumonia

develop more in the lower lobes. For the animals of this series, these

facts are not borne out. In the accompanying list will be found our

acceptable cases of abscess and gangrene. Little can be said about

incidence save the fact that the highest percentage and number occur in

the Carnivora. It will be found that the right lung is affected nine

times predominatingly while the left lung is affected seven times. The

lobe most often singled out for an isolated lesion is the lower left,

the right middle being the next most often affected. These figures

concern the mammals alone, the three birds being considered too few to

discuss. It cannot be said from these figures that there is in animals

any definite distribution of pulmonary abscess and gangrene.

Nor do these figures correspond to those appearing in literature of

human pathology. In man inspiration of foreign bodies, including

bacteria-laden mucus, usually carries them into the right lung because

of the larger and more directly vertical bronchus to that side. Emboli

go as a rule also to the right lung more than to the left because of the

greater size of the pulmonary artery and more direct blood current to

that side. In these animals right side lesions are more numerous but the

left lower lobe is the principal segment of the lung to be affected. The

cases are too few and the anatomy too variable to permit any deductions.

There is in the affected animals no uniform anatomical peculiarity which

would explain the predominance of the right lung as a whole or the left

lower lobe as a unit.

PNEUMONOKONIOSIS.

Pneumonokoniosis, because of its importance in industrial diseases, has

been subjected during recent years to considerable intensive study in

human medicine, from which activity some interesting and useful

information has been obtained as to its genesis and effect upon the

function of the lung. This condition is of course a purely environmental

one, the degree and particular kind of “dusting” being dependent upon

the duration and nature of exposure of the particular individual. This

Garden is situated beside an active railroad trunk line so that the

opportunity for coal dust inhalation is continuous. The degree of

anthracotic pigmentation of the lungs and related serous membranes is

really negligible and with one questionable exception, we have not seen

fibrosis due to this cause in any animal. The one exception, an amazon

presented and living in the Garden but three months, at necropsy showed

an interstitial chronic bronchitis and pneumonitis stretching out from

the hilum, all of the affected area being deeply pigmented. The picture

was comparable to what might be expected from a second degree

anthracotic fibrosis of Landis and Pancoast. Many specimens come to

autopsy with some grade of pigmentation, but none, except the one above,

with resultant fibrosis. The degree of anthracosis is usually so slight

that it has been considered important enough to include in the diagnosis

but eighteen times and curiously enough seventeen of these were observed

in birds. Were there more cases it might be profitable to plot their

exhibition period but the use of this small number might lead to error;

the average length of exhibition of the birds was about a year. It is

common to observe some black specklings of the air sacs, as if pepper

were dusted on them as has been said before, but even this is rarely

marked. It is most often seen in the Anseres, Psittaci and Struthiones

but a goodly number of cases occur in the long-lived Passeres.

The distribution of the pigment is essentially the same throughout

Mammalia—peribronchial, submucous and in the lymph nodes at the root of

the lung. In the birds it is first seen in the subepithelial spaces of

the septa of the small alveoli where they project into the secondaries,

later accumulating in the connective tissue of the main septa.

Collections under the pleura and at the root of the lung are rare, the

dust usually spreading out along the air passages into the air sacs.

Other forms of pneumonokoniosis are unknown. Although animals must

inspire much dust from dry feed and from floors it must be caught early

and removed by snorting or by the lymphatic drainage. It seems fairly

well accepted that dusts are dangerous to the degree that they contain

inorganic substance and as these animals are not exposed to concentrated

mineral or metallic dusts, no effects are seen.

INFARCTION OF LUNG.

Infarctions of the lung, while not at all common, are interesting

because of their incidence in the Carnivora and in the distribution. The

figures concern the mammals only since the decision for or against

infarct in the birds is very difficult because of the frequency in this

class of hemorrhage with pulmonary congestion. There were eleven single

or double non-septic infarcts, of which seven occurred in Carnivora, one

in an ungulate, two in Primates and one in a rodent. The existence of

parasites was excluded in most of the cases but could not be entirely in

all. Eight of these infarcts were on the left side, five of these being

in the lower lobe.

EMPHYSEMA.

Emphysema of the atrophic and chronic vesicular types with the soft,

fluffy, pigmented or pale pink organ has not occurred in the animals

under observation. Acute vesicular emphysema, such as is seen in chronic

bronchial and cardiac diseases, has been encountered several times.

Cardiac lesions were found four times, nephritis eleven times, acute

enteric conditions seven times, hepatic diseases seven times. Two cases

of wide spread amyloid disease showed a deposit of this substance in the

alveolar walls. It is quite common to find some grade of emphysema in

monkeys dying from osteomalacia and rickets. The process is then most

prominent in the upper lobes and along the free anterior margins. The

incidence in the orders is Primates 5, Lemures 2, Carnivora 2,

Pinnipedia (drowning) 1, Rodentia 1, Ungulata 4, Marsupialia 4. The best

example was found in a Skunk (_Mephitis mesomelas_) having a general

infection, emanating from the cranial sinuses, and cardiac dilatation.

Emphysema does not seem to occur in birds for only one was seen which

seemed to present this condition. This was a Bald Eagle (_Haliæetus

leucocephalus_) with chronic renal and enteric disease and cardiac

hypertrophy. The lungs were tensely distended under their serous

covering and showed a few small bullæ anteriorly. Unfortunately a

histological preparation is not at hand.

TUMORS.

Tumors of the lung are moderately common, both of primary and secondary

origin. Thus we have seen three primary and six metastatic growths in

mammals and one of each kind in birds. The primaries were: carcinomata

in a civet (_Viverra tangalunga_), a bandicoot (_Thylacomys lagotis_), a

kangaroo (_Macropus rufus_), and a lorikeet (_Glossopsittacus

concinnus_). The secondaries were: carcinomata in a black bear (_Ursus

americanus_), a polar bear (_Ursus maritimus_), a lion (_Felis leo_),

and a dasyure (_Dasyurus maculatus_); sarcomata in a prairie wolf

(_Canis latrans_), and a raccoon-like dog (_Canis procyonoides_);

adenocarcinoma in a chestnut-eared finch (_Amadina castanotis_).

The histological character of the primary cancers would place them in

group of the nodular and infiltrative types of Kauffman. They all seem

to have taken their origin from the smaller bronchi, the usual starting

point. The growths were small in the civet and bandicoot and strongly

suggest that the tumors arose in bronchi occupied by parasites; such

bodies could not be demonstrated. It is the usual thing to find in cases

of parasitism of the bronchi that if there be no ulcerative destruction

of tissue the epithelium undergoes some form of hyperplasia, and even

structural metaplasia in the air tubes supplied with cuboidal or

cylindrical cells. Epithelia many layers deep have been encountered,

usually arranged in orderly fashion but frequently “papillomatoid,”

suggesting the epidermal layers yet not so far as to show protoplasmic

bridges. Distention of various degrees, affected by the contents of the

tube and the surrounding inflammation, are common. Such a picture

naturally resembles epithelioma and indeed growths of this nature are

reported as due to verminous pneumonitis.

There are, especially in cats and dogs, small scattered adenomatoid

growths[21] under the pleura and in the pulmonary substance, thought to

originate in the alveolar epithelium and occasionally growing to large

size; the case in the kangaroo may have had this origin. _It was the

only primary tumor to give metastasis_ (to the spleen and gastric wall),

the secondaries being decidedly adenomatous in character.

Metastatic growths come from the following originals: two from the

thyroid, well known to give pulmonary embolism in dogs; one each from

the breast, uterus, adrenal, intestine and kidney. The form assumed is a

gray and red mass lying under the pleura or an isolated nodule in the

substance. Sarcomatosis, the form apparently spreading out from the

hilum and growing in isolated grayish tubercular masses, has not been

seen.

THE PLEURA.

The pleura is a tissue apparently quite susceptible to infection in

mammals and so closely associated with the air sacs in birds as to be a

part of the same membrane, therefore the two being affected together.

Throughout the higher class all orders give copious examples of the

involvement of the pleura, principally of course as an accompaniment or

a sequel to pneumonitic or bronchitic processes but also as a part of

acute infectious diseases, such as hemorrhagic septicemia,

pleuropneumonia and the like. However two orders present such a number

of instances of pleuritis that they deserve notice. The seals,

Pinnipedia, of which we have twenty autopsy records, showed inflammation

of this membrane four times, three of which were dependent upon

pulmonary infection and one apparently due to general septicemia with

trifling damage to the lung proper. One of the first cases had gone on

to empyema of the classical type, a shrivelled dry almost carnified lung

with a thick fibrinopurulent covering. The lung of the seal is well

divided into lobules, the external surface being generously supplied

with lymphatic channels under the pleura, an arrangement which should

carry away infection one would think. Perhaps this high percentage of

pleurisy in our Pinnipedia is but accidental. The marsupials, while

having a notable percentage of pleurisy both among all the cases and in

relation to the number of postmortems, are not so striking from the

etiological standpoint since practically all of these have suffered with

Kangaroo mycosis or pneumonia. In over half the cases of this infectious

disease some grade of pleuritic exudate has been observed, only one,

however, going to the stage of empyema.

One cannot speak so definitely of pleuritis in birds since this tissue

merely represents in them the covering of the lung and is firmly

attached posteriorly to the ribs and anteriorly to the air sacs.

Exudates show as collections upon the air sac side of the combined

membrane, pleuritis proper in birds being an infiltrative affair coming

through the pulmonary tissue and therefore being a part of pneumonitis.

I notice a tendency in a few articles to write of pleuritis when the

process is confined to the thorax but this gives the impression that the

disease is peculiar. There seems no difference in the gross and minute

appearance between thoracic serositis and panserositis. The course of

procedure seems to be from the anterior or mesial pulmonary ostia into

respectively the cervical and thoracic air sacs and this seems to hold

good whether the infection be mycosis or fowl cholera or fowl pest.

There are records of 104 cases of serositis in birds of which 45 were

among parrots, the remainder being well distributed among the various

orders; only two each occurred in Galli and Anseres, orders prominently

affected under domestication. This high percentage of pleuroperitonitis

among parrots and their congeners can only be explained upon the ground

of a continued infection of our stock by the virus of fowl cholera and

by mould. One case of undoubted fowl cholera occurred recently and as

the records are reviewed a few are discovered where the organism was

found. The virus must be of low grade for we have had no severe and

devasting epizoötic. Mycosis is constantly with us no matter what we do

in hygienic measures. There was a small group of cases of pulmonary and

serous membrane mycosis combined with staphylococcus infection which

carried off six birds. The pathology of this group was interesting

because one could follow the infection of the bacterium. The anterior

pulmonary ostium was surrounded or covered by a mycotic mass and

spreading downward from this was a grayish yellow turbidity of the air

sac walls with a delicate sticky or almost mucilaginous exudate

extending into the lateral abdominal and posterior sacs.

[Illustration:

FIG. 12.—ENDOTHELIOMA OF PLEURA. LEOPARD (FELIS NEBULOSA).

]

[Illustration:

FIG. 13.—ENDOTHELIOMA OF PLEURA IN FIG. 12. DETAIL OF ONE OF THE WARTY

EXCRESCENCES.

]

There is on record one tumor of the pleura, an endothelioma, in a

Clouded Leopard (_Felis nebulosa_). It was the usual plate-like

thickening with warty excrescences. No metastases occurred. (Figs. 12

and 13).

SECTION VII

THE ALIMENTARY TRACT. PART 1.—PHARYNX, ESOPHAGUS, STOMACH AND INTESTINES

The portion of the anatomy that we now approach varies in construction

almost as much through the animal kingdom as do the external shape and

covering of the various orders and much more than do the other systems.

The reason for this is obvious, an arrangement accommodative to the

differing food chiefly, but not a little to the ease with which animals

obtain and assimilate their nutriment. It would be impracticable to

describe all the variations of the orders discussed in this study, but

since certain gross and minute differences are of importance in

comparative pathology they will be discussed at the appropriate places.

It is my purpose to present in a subsequent section a discussion of food

in captivity from the standpoint of its quality and quantity in relation

to pathology.

Doubtless the quality of food is the largest factor in the production of

disease both of the alimentary tract and elsewhere, but I am not at all

sure that the quantity may not be equally important, in certain groups

at least. Thus, for example, the ungulate has nearly always available in

bedding a substance that he can and will eat, and the prevalent idea

that an animal will eat only as much as is good for him seems not to

hold at all times, since overfilled rumens are only too common. It might

be thought, however, that captivity creates a sort of pica, or that

enforced idleness is conducive to gorging. The use a few lines above of

the word “doubtless” may have arrested the attention of some, yet when

the whole subject is reviewed it seems entirely justified. Plimmer puts

incorrect food at the head of the list of the causes of enteritis,

Brooks emphasizes the importance of certain grasses and musty fodder,

systematic writers detail among the principal causes of gastritis

spoiled food, and in zoological gardens specific disease like hog

cholera and enterohepatitis are relatively uncommon while nonspecific

gastroenteritis is the most frequent diagnosis in causes of death.

The other factors to which enteritis is ascribed are animal and

vegetable parasites and mechanically operative foreign bodies, the last

being unimportant. Just how important the first mentioned are is a

matter of some question which must be subjected to considerable study

before any solution can be expected.

If for no other reason than that the gross and minute pathological

anatomy of gastroenterocolitis is the same through the mammals and birds

(aside from a few specific lesions like enterohepatitis, typhoid fever,

etc.), while the food and bacteria vary, it would seem probable that the

ultimate cause is the same, a poison which can be formed alike in the

carnivorous and herbivorous gut, and not dependent upon bacteria, but

upon the chemistry of the food or of the intestinal mucosa. To put the

matter more simply, the lesions being the same under nearly all

conditions is not the cause the same, and is it not a poisonous product

from food or the intestinal lining. It is profitable here only to

mention the marked similarity of enteric lesions under the differing

conditions and in different orders. We shall study chartwise, the

various forms of inflammation from the cardia to the anus in terms of

their anatomical diagnosis and most probable etiology in an attempt to

throw light upon the matter, and later present the physiology. System

requires, however, some attention first to anatomical order so that a

brief review of the esophageal and pharyngeal conditions is indicated.

PHARYNX.

The buccal-pharyngeal cavity in mammals is used chiefly as a passage way

for food and as the place where some of them triturate and insalivate

the bolus. Certain orders, Primates, rodents and marsupials, use this

cavity thoroughly at the first mastication, others use it little at

first but may ruminate, the ungulates, while strict carnivores use it

very little. The Aves use their pharynx almost exclusively as a passage,

and, despite the presence of a certain amount of salivary gland tissue,

probably do not digest any substance in this cavity. The crop or

ingluvies is a sac to permit of salivary digestion but is really a

storehouse to allow rapid feeding without overfilling of the

proventricle. The esophagus extends from the pharynx to the cardiac

opening of the stomach in mammals and widens into the glandular stomach

or proventricle in birds, the upper end of which lies in front of the

lower third of the left lung behind the heart.

Inflammations of the buccal, pharyngeal and esophageal walls are

relatively common in certain orders especially ground birds and grazing

ungulates. This would seem to be explained on the basis of injury to the

mucosa by sharp or pointed objects picked up while feeding. The

character is usually necrotizing, but need not be, and the bacteriology

is not specific. Definite infectious diseases like diphtheria and

actinomycosis are not included here, but it might be mentioned that the

second disease cited is believed to be started by the penetration of the

organisms into wounds made by sharp grasses. Certain orders, notably

Ungulata, Passeres, Psittaci and Struthiones, are quite susceptible to

mycotic infestation and we have seen an outbreak of thrush in Kites

(Accipitres). It is, however, interesting and possibly significant of

peculiar protective powers in the upper alimentary tract, that strict

carnivores have failed to show ulcerative, purulent or necrotizing

inflammations of the mucosa from the mouth to the cardia. There has been

no important data upon ingluveal indigestion or esophageal obstruction.

Birds especially, and occasionally mammals, gorge themselves or take too

large a bolus, but it seems as if this is only fatal where some distinct

important pathology is present which has reduced their resistance. In

the lower esophagus one has to deal with worms in connection with the

proventricle in birds, but no mammals seem to have suffered with

temporary or permanent strictures. “Crop-binding” has occurred in the

following orders: Psittaci, Galli; and overfilling of the esophageal

dilatation was seen in Accipitres and Herodiones; Columbidæ with their

double crop were not affected by this abnormal collection of food in the

esophagus.

DILATATIONS OF ESOPHAGUS.

The mammals have shown three dilatations of the esophagus interesting

enough to detail briefly:

Mongoose Lemur (_Lemur mongoz_) ♂ . Sacculo-fusiform dilatation of

esophagus, probably congenital, with adjacent fibrosis of lung. In

poor condition for several years but recovered satisfactorily from a

bad cut inflicted by cage-mates. At autopsy the general condition is

poor, hair missing in spots, all skin dry and atrophic with patches of

keratotic dermatitis. All tissues anemic, muscles lusterless. Right

lung collapsed, brown and pink, spotted with anthracosis. Left lung

pushed forward and to left by a mass in the posterior mediastinum.

Lower lobe in its posterior portion is adherent to esophageal mass.

Lower half of this lobe beginning where bronchus ends and extending

over anterior-posterior surfaces shows marked fibrotic processes and

at one point in tissue between end of bronchus and adherent esophagus

there is no lung tissue remaining. No recent consolidations. Bronchial

lymph nodes, small, firm homogeneous pale brown with specks of

anthracosis. Heart contracted, normal in size, firm red-brown. Aorta

is firmly adherent to esophageal mass where bronchus crosses it. The

lower half of the esophageal from the hilum of the lung to the cardia

is the seat of a dilatation, fusiform for the most part, but with a

saccular portion anteriorly. This latter presses the left bronchus

upward and heart forward. The wall of the tube is slightly irregularly

thickened but there is no cicatrix and mucosa shows slight

hypertrophic condition. A large mass of food occupies the dilatation.

Stomach is empty save for gas. Mucosa is soft, smooth, pale pink.

Duodenum shows slight swelling of the rather pale yellow submucosa and

mucosa, but the tips of the villi are injected. Intestine contains

only a little slimy mucus. Large intestine contains a mass of

constipated feces. The esophageal dilatation seems to have been

congenital although it is barely possible that the fibrosing

pneumonitis and pleuritis may have aided and caused it by traction. It

has been doubtless the cause of the animal’s inanition.

Black Bear ♂ (_Ursus americanus_). Sacculate dilatation of esophagus

with chronic esophagitis. Chronic hypertrophic gastritis. Chronic

lymphadenitis. Fatty degeneration of liver. Acute catarrhal enteritis.

Had been vomiting more or less, nearly every day for two months and

did not eat for six days before death. Mouth, pharynx and esophagus

are full of macerated, unrecognizable food. Pharynx seems normal.

Larynx is yellow, mucosa rough and slightly thickened in places

especially just above the vocal chords. No excess of mucus. Esophagus

in neck is dilated. Mucosa is rough, irregular yellow brown. This

dilatation proceeds downward so that at thoracic opening tube is twice

normal size. Upon entering thorax this dilatation turns to right and

in irregular saccular form extends to diaphragm compressing heart and

lungs to left. The main course of it then recrosses the midline, aorta

being slightly twisted as it regains position in front of vertebræ.

The wall is irregularly thickened from pseudomembranous patches and

some hypertrophy of mucous and submucous layers. Muscle and serous

coats are considerably thinned. The sac is full of macerated food and

gas. The right lung is compressed small resilient red gray. No

adhesions in either pleura. On section the lung tissue is found to be

slightly edematous, red gray, compact and while not atelectatic yet

crepitates much less than normal. Left lung is the seat of passive

congestion in lower lobe and lower half of upper lobe. The upper half

of lobe is compressed and subcrepitant like the right lung. Lymph

glands of neck and thorax are much enlarged firm with large irregular,

clear outlined follicles and brown firm homogeneous pulp. The aorta

shows slight roughening, the intima being smooth and homogeneous.

Lion ♂ (_Felis leo_). Ten and one-half months old. Cystic

parenchymatous goitre, dilatation of esophagus, ulcerative enteritis.

Acute glomerular nephritis. Chronic hyperplasia of spleen. Fatty

infiltration of liver. Bronchopneumonia (from pressure of goitre).

Ascaris in intestines. Had lump on neck for several weeks, ate very

little and seemed to have hard work to get anything down. Stopped

eating toward the last and vomited water and foam. There is a small

ulcer with everted lips just below left incisor on lower lip which the

keeper says is of several months’ duration. The thyroid is much

enlarged and forms a large mass in the upper chest and extends far up

in the neck. Because of this mass the lungs are pushed far down in the

chest. Heart also lies very low. The thyroids are enormously enlarged

and cystic, the right measuring 13 × 8.5 × 5 cm. and the left

19 × 9 × 5 cm. The lungs are pale pinkish white. Air content increased

in places, decreased in others. No hypostatic congestion. The lungs

seem normal except at the apex where they are collapsed probably from

pressure on lung by enlarged thyroid which dips down into the chest

for at least three inches filling entirely the apex of the chest. One

bronchial lymph gland was about the size of a walnut, the rest were

normal. The heart seems normal except for its slightly low position.

The abdomen contains about 300 c.c. of deep yellow highly albuminous

fluid. No adhesions. The liver is softer than normal, glistening,

smooth, moist and very yellow particularly at the edges. The gall-

bladder contains a green mucoid bile and the duct is patulous. Spleen

and kidneys are normal. Mouth and pharynx are normal. The esophagus is

much dilated above the thyroid. The enlarged thyroid pressing upon it,

has acted as a distinct obstruction. In this pouch was a large amount

of food probably (from the history) eaten two days before. The

esophagus below this point was normal except for the presence of thin

mucus. Stomach empty save for two small bits of meat. The duodenal

walls are much thickened, mucosa covered with small ulcers many with a

hemorrhagic base; there were present also a few small, round worms.

[Illustration:

FIG. 14.—DILATATION OF ESOPHAGUS. LION (FELIS LEO). DILATATION

PROBABLY DUE TO OBSTRUCTION BY ENLARGED THYROID BODY. IN

ILLUSTRATION DISTENTION OF ESOPHAGUS CAN BE SEEN IN THE FORK OF THE

THYROID LOBES.

]

Here are presented three different dilatations, the first probably

congenitally started and aided by pulmonary fibrosis, therefore

secondarily a traction diverticulum, the second probably entirely

congenital, and the unusual third case due to obstruction by an enlarged

thyroid. In this connection might be mentioned small saccular

diverticula in the proventricle of a Fire Finch (_Lagonosticta

senegala_), and at the pylorus in a Puma (_Felis concolor_). Neither of

these seemed of any significance and played no part in the death of the

animals; they did not seem to be artificially produced, by worms, for

example.

THE PROVENTRICLE.

The proventricle or forestomach of birds, is the seat of active

secretion of the gastric juice in nearly all orders, although Jobert

believes that the mucosa of the gizzard may contribute some digestive

fluid, and there are active glands in this tissue in a few orders. The

proventricle does not act as a reservoir during digestion, but as soon

as the juices are well mixed with the bolus the food is passed on to the

gizzard. The organ has a rather free position, at least as far as its

left lateral and downward movements are concerned for the left lateral

abdominal air sac is free on that side of the gastric complex and the

left lateral thoracic also extends down the side of the proventricle.

Upward and anteriorly is the heart. Some of the cases of proventricular

spiropteriasis have shown very marked congestion of the left lung,

possibly due to the closure of the anteroinferior air sac aperture on

that side. Aside from parasitism, affections of this organ are not very

numerous.

Infestation with spiroptera and with less dangerous worms was quite

serious at one time, but since routine examinations of all suspicious

birds has been practiced this parasitism has been under control. This is

a subject of especial importance to collections, and will be described

in a special section. The susceptibility of the proventricle to damage

seems from our figures to be very distinctly a matter of zoological

order. In so far as parasites are concerned, the parrot group stands

away ahead of all others having an incidence among autopsies upon

Psittaci of 16 per cent.; after them come the Picariæ with 9 per cent.,

and Columbæ and Passeres each with 4 per cent. When, however, non-

verminous conditions are reviewed the anserine birds are found the most

susceptible, 3 per cent. of the autopsies upon this order revealing

proventricular lesions; after them come the Columbæ, 2 per cent., and

Psittaci, 1.5 per cent. In this group are included inflammations of all

kinds, dilatations and distentions and some lesser matters.

This part of the stomach has been involved in our cases of fowl

diphtheria, showing a distinct mucopurulent inflammation with

penetration into the depths of the glands; no separation of the mucosa

occurred, but ulceration was seen. Perforation was observed thrice,

twice by ulceration around a worm while it was boring into the muscular

layer and once, in an ostrich, by the penetration of a nail. Obstruction

of this division of the stomach by impaction of food and stones is not

common, but does occur. The reason for such obstruction is usually very

obscure. Sometimes it seems due to the feeding of seeds and the like in

too finely divided form, whereby food and pebbles are taken up together.

Some of the smaller birds have had in times past too many small pebbles

in the cages, while others have had too large seeds, thus apparently

trying to use the pebbles to crush them. It would seem also that the

birds had really eaten too much and could not accommodate it in the

gullet and gizzard; this seems surely true in three or four Accipitres.

Most often, however, we have had to fall back upon the inadequate

explanation of pica or perverted appetite.

Impacted proventricles and gizzards have been observed thirty-four

times, in eight of which it seemed the sole cause of death, and

therefore probably entirely due to foreign bodies in food. The theory is

accepted that dilatation and obstruction will not occur if the motor

power of the gastric wall be normal and no inflammation exist. In this

regard we can only discover five birds (the mammals will be discussed

later) with any distinct inflammatory or degenerative disease of this

part of the anatomy and two with lesions elsewhere which might affect

the musculature; this leaves the vast majority of gastric obstruction in

birds unexplained on basis of defective motor power, therefore probably

dependent upon the character of material consumed. The anserine birds

and parrots are most often affected by this form of obstruction.

Acute or chronic dilatation of the forestomach and gizzard is very rare

in birds, it having occurred only thrice in our records, a finch, a

parrot and an owl; the causes were entirely unknown since the cavities

were not overfilled with food.

THE STOMACH.

Impaction of the mammalian stomach is a diagnosis made but once in our

records, an Indian Antelope (_Antilope cervicapra_), and this is viewed

with suspicion. The rumen was undoubtedly tightly packed, being

distended to its fullest capacity with rather dry and not properly

softened grain. However, postmortem changes had advanced and therefore

observations in the whole body were not dependable. The bulk of food

which can be accommodated by the rumen is very large, and had this not

been dry and firm the condition might not have been interpreted so

seriously. Many animals come to autopsy with a well filled, indeed even

with a well packed stomach, but there is usually sufficient reason for

this or there is distinct pathology to account for death.

All this of course implies a stomach of normal or approximately normal

dimensions since distention beyond this, or dilatation of the stomach,

is more definite. In veterinary medicine, gastric tympanites (rumen

alone or all stomachs, or the simple stomach) is ascribed to food that

ferments easily when taken in excess or in the presence of defective

motor power, to constrictions by scars and to obstructive tumors;

excessive feeding is sometimes mentioned but given a subordinate rôle.

Our records throw very little light upon the subject since only five

cases were observed. Four of these five seem to be due to acute

fermentation independent of gross physical obstruction, while one, a

Cape Hunting Dog (_Lycaon pictus_) showed an old chronic ulcerative

gastritis with both healed and active ulcers distorting the pyloric end

of the organ. Three of the first mentioned four were monkeys and one was

an ocelot. The stomach of the voracious monkey is at time of dissection

usually well filled, but in these cases there seems no doubt that gas

and excess fluid had distended the cavity enormously, in one instance

apparently assisting in acute cardiac dilatation. There were no obvious

reasons for assuming any damage to the gastric motor mechanism.

[Illustration:

FIG. 15.—ROUND ULCERS IN STOMACH WALL. COMMON OPOSSUM (DIDELPHYS

VIRGINIANUS). THERE IS GENERAL MODERATE CHRONIC GASTRITIS WITH ROUND

ULCERS NEAR THE CARDIA.

]

GASTRIC ULCERS.

Gastric ulcer, so-called peptic or round ulcer of the stomach, having a

chronic course and leading to radiating scars of the mucosa is not

common in the lower animals, but frequent enough in the human being. The

form of ulcer in question has at present no adequate explanation, or at

least there is no one cause which will answer for all cases. Local

injuries from within or without the stomach, bacterial embolism,

entrance of bile through the open pylorus and many other factors have

been named in the causation but can seldom be used in any given case. In

the lower animals with their relatively frequent parasitic infestation,

another factor is added. In analysis of our statistics I have separated

ulcerative gastritis from parasitic and mycotic ulcerations and from

peptic ulcers; the first is discussed in later paragraphs. Parasitic

ulcers of the stomach occur chiefly in our native marsupial, the

opossum, and in some Carnivora; physaloptera, strongylus, ascaris, and

gastrophilus have been found. The kangaroos are frequently affected (8

cases) with an acute or subacute ulceration of the gastric wall, without

much general gastritis. The lesion is peculiar in appearance. The

youngest ulcers are black or dark gray, flat necroses of the mucosa

alone and indeed the process very frequently penetrates no deeper. Older

lesions spread laterally and may be preceded by a very narrow congested

line but there is no raised edge nor does there seem to be submucous

infiltration. If the process be rapid a loose dirty slough may form.

Certain of the advanced cases of Kangaroo mycosis will present more

infiltrative lesions of the gastric wall leading to large and well

defined necrotic areas; they may at times penetrate the whole wall

outward. (See page 580.)

True peptic ulcers have been found in Primates, 4; Carnivora, 5;

Pinnipedia, 2; Insectivora, Ungulata and Hyraces each one. The London

Garden reports that gastric ulcerations occur most often in Carnivora

and Marsupialia. Those in the last three orders of our list were small,

usually multiple and relatively superficial. The ulcers found in

Primates and Carnivora present the usual pictures seen in man. In one

example in each of these orders radiating scars of healed defects are

mentioned in the notes. None of them seems to have led to cancer, and in

only one, a wolf (_Canis lupus_), was the scar tissue sufficient to

cause definite impediment to the motility of the stomach. Six of the

fourteen examples appeared on the greater curvature, the remainder on

the lesser. Ten ulcers were in the pyloric division, the other four

being scattered. No other pathology is found common to these cases which

might be drawn into etiological association.

TUMORS.

Tumors of the gastric complex are not at all common, there being only

the following to report: Primates, Hamadryas Baboon (_Papio hamadryas_),

diffuse adenoma; (none in Carnivora with the most ulcers); Marsupialia,

Red Kangaroo (_Macropus rufus_), malignant papilloma with metastases.

The former tumor, shown in Fig. 17, was a diffuse soft excrescence

beginning near the pylorus and stretching along the lesser curvature

toward the cardia. Histologically it was made up of glandular acini

growing in all directions but always maintaining normal relations of

cells and basement membrane. There were no metastases and other reasons

for death existed. The tumor of the kangaroo stomach was a true

epitheliomatous cancer with metastases to liver, spleen, and kidney.

Only one secondary tumor was observed, from a carcinoma of the lung in a

Red Kangaroo (_Macropus rufus_).

[Illustration:

FIG. 16.—MULTIPLE GASTRIC ULCERS. COMMON WOLF (CANIS LUPUS). CHRONIC

GASTRITIS WITH NUMEROUS IRREGULAR ULCERS OF THE PEPTIC TYPE.

]

[Illustration:

FIG. 17.—PAPILLOMA OF STOMACH. HAMADRYAS BABOON (PAPIO HAMADRYAS).

]

THE INTESTINE.

Inflammation of the gastrointestinocolic tube is the most important

single condition with which handlers of animals have to deal, and

unfortunately it can seldom be diagnosed clinically, early and

accurately enough, to make treatment useful. At this Garden some

evidence of acute or chronic disease of the tube has been present in 31

per cent. of our autopsies. The reports of other gardens would indicate

that their figures might be quite close to this. What is the cause of

this high mortality? Incorrect feeding, qualitatively or quantitatively

has been put at the top of the list by Plimmer, but he adds other less

important factors: Bacteria of infectious power, protozoa, foreign

bodies and parasites or their mural cysts. In order to evaluate

approximately how each of these acts let us review the causes as they

are generally known and later discuss the pathology as seen in the

various orders.

(1) Overloading of the stomach by too much food or by rapid eating of a

hungry animal is of importance under certain domestic circumstances

where times of feeding are irregular or intervals are too long, but this

cannot occur in any well regulated menagerie. It is possible, however,

that overfilling might occur in certain Ungulata, which have hay and

straw nearly always available, if the food in their reach happens to be

particularly agreeable or tasty to them.

(2) Insufficient mastication would seem to be important only in those

orders which depend upon this action to triturate, insalivate and

macerate their food, of which Homo, Primates, Ungulata and Marsupialia

are the principal ones.

(3) Disturbance during and after feeding has always been believed to

affect digestion unfavorably, and it may be that visitors to a

collection exert such an effect; this factor is probably negligible.

(4) The appropriateness of the food is a very important factor in the

health of an animal under captive conditions. Diet lists are made up by

officials largely according to the known habits and general physiology

of an animal, but the food offered can at best only approximate what the

wild beast obtains for himself. It does not follow because a selected

diet may seem to provide all the elements contained in the food

available under natural conditions that it actually does so, especially

since we are aware that some essential food factors, known under the

term vitamins, are necessary to best development. These substances vary

in closely similar foods, and seem to be higher in simple natural foods

than in prepared diets. We have seen in this Garden that the inorganic

constituents must be correctly represented in the food, else

degenerative osseous condition may develop. Inappropriate diet may

express itself at once after the receipt of an animal, by its sickness

or death, or after some time in the development of chronic tympanites,

chronic intestinal catarrh or bony deformities.

(5) The physical condition of food is a matter of no small moment. The

taking of soft food in large quantities especially by herbivorous

animals, permits too short a sojourn in the gastric fundus and is often

followed by pyloric and duodenal disease. Too firm food may pack the

rumen, fundus or proventricle as the case may be, and be succeeded by

distention of these parts and catarrh of the pyloric and intestinal

area. The effect of foreign bodies mixed with food is difficult to

evaluate unless of course they be of such a nature (pointed metal and

the like) as directly to traumatize the mucosa. Many birds and mammals

come to autopsy with a relatively large number of stones and small

sticks in the stomach without any distinct evidence that they have been

hurt thereby. In the bird the stones may be so large and numerous as to

leave little room for food, or small enough to pass out into the

intestine where they undoubtedly may pave the way for bacterial action.

Smoothly polished pebbles in small quantity seem to have little effect

in mammals. Hair balls are not common and unless of large size are

apparently unimportant. Considerable sand mixed with food has a

distinctly irritating effect. It is perhaps best known as a chronic

gastric disorder of horses; we have seen it in zebra.

(6) Spoiled food is obviously a very prime factor in inflammations of

the gastrointestinal tract. Its operations are illy understood except

perhaps when products of fermentation or putrefaction prevent digestive

action or are absorbed. If in small quantities not sufficient to cause

acute fermentative inflammation or intoxication, such substances

frequently taken may doubtless produce chronic catarrhs. Many animals

are fed upon vegetable mashes, or stews which can decompose, while bad

meat may occasionally be fed. We had a rather serious outbreak of

enteritis in small Carnivora from the use of fowl heads obtained at

hotels; some of these cases were shown to be due to B. paracoli, thus to

be looked upon as infections. Dirty food while not spoiled may carry

with it organisms of decomposition, or of infective qualities, or the

dirt may act as an irritative foreign body. We have found that for

delicate ungulates (antelopes) it is highly desirable to screen grain,

and that the grade of hay should be of the best.

(7) Infectious conditions are of great importance under certain

circumstances but with the exception of hog and fowl cholera, the

dysenteries and a few other diseases, do not as a rule play a great part

in mortality as specific diseases unless of course an epizoötic appear.

The greater problem is to understand bacterial action in the face of

other factors. Are infectious germs introduced with food and drink in

every case of gastroenteritis or do some other factors activate those

already present in the gut tract? Unfortunately these questions cannot

be answered directly. We can, however, point out which groups of

bacteria are most common in some of the orders, which orders are most

susceptible to bacterial invasion and which to local lesions with

intoxication. The greatest problem in the field is the interrelation of

germs of various sorts in the intestinal tract. Certain varieties are

known to develop intoxicating aromatic substances, others to elaborate

or excrete fatty acids, still others to form antiferments but the

conditions existing in the various kinds of intestinal tracts are too

little understood to help very much in this study.

(8) Animal parasites have long been considered as one of the causes of

gastrointestinal inflammation, a condition largely due to copying from

book to book of a few facts and more impressions. The sum of reliable

information to-day would seem to indicate that a few parasites—uncinaria

being the most conspicuous example of this type—draw considerable blood

from the mucosa, that a few, like uncinaria and dibothriocephalus,

elaborate an absorbable toxin, that some, notably ascarids, produce an

irritating substance, and that many possess the power in themselves or

by some excretion to act as antiferments. These factors, were they all

combined in one worm, might probably irritate the mucosa sufficiently to

produce inflammation, but it is not easy to imagine that they would

cause an acute specific condition. It is much more easily conceived that

with tiny hemorrhages or ulcerations of mucosæ, bacteria might get in

their work or if considerable ferment were neutralized, maldigestion,

flatulence or indigestive irritation would ensue. With certain worms

like esophagostomum there is considerable evidence to show that a

chronic fibrous disease of the intestinal wall arises, but in this case

the parasite resides in the mucosa and acts as a foreign body. It would

seem, however, that the most important influence that animal parasites

exert is to be found in the preparation of the mucosa for the action of

bacteria. Masses of parasites may of course physically obstruct the

lumen and lead to intestinal stasis and dilatation.

INFLAMMATION.

In analyzing the cause of a gastroenteritis and its consequent effect

upon the wall of the tube and upon the viscera, certain physical,

chemical and physiological factors must be considered. Whether this may

be directly the effect of bacteria or poisons from worms or some other

factor seems of little moment since in any fully developed case,

symptoms and effects are comparable. Moreover it seems that pathological

anatomy, both gross and minute, is essentially the same from Primates to

struthious birds, the highest and lowest of the two classes here

considered. By this is meant that the acute congestive condition of the

gut tract with solution of the surface, to which we have applied the

name of toxic enteritis, seems to be met with in this form throughout

all the orders. So too catarrhal inflammations are the same to the naked

eye and under the microscope, due allowance being made for the fact that

mammals use polynuclear cells for exudative purposes while birds employ

mononuclears. Concomitantly with these conditions, a degenerative

process may be going on in the liver and kidney, and hyperplasias,

especially in the true infective processes, will be found in the related

lymphatic structures.

The majority of students to-day place responsibility for gastroenteritis

upon the bacteria known to be present in the various intestinal tracts,

mentioning especially colon and proteus groups, streptococci, the

necrosis bacillus and anaerobes of the Welch class. In a few of our

studies of intestinal bacteria in cases of enteritis one thing has been

very definite and that is that in the intestinal content of animals

whose food is largely meat, Gram-negative bacilli have predominated,

whereas in herbivorous animals Gram-positive organisms have been most

numerous. From the observations of Kitt, Strassberger and some others,

the normal flora of domesticated animals is subject to wide variations

so that our observations must receive confirmation before they are

finally acceptable. We have on several occasions isolated from

carnivorous intestines Bact. paracoli, Bact. suipestifer and other

members of this group. We have no reliable cultural data upon the

herbivorous intestine and can only quote the Gram pictures as mentioned

above. On two occasions, an eland and an elk, a very large number of

forms corresponding to necrosis bacillus were seen; to this organism

Kitt gives considerable power in the production of necrotizing

processes.

TABLE 11.

_This table shows an analysis of all cases of gastroenterocolitis. The

left half of the table is an analysis of orders upon which one hundred

or more autopsies have been done, the right half of orders with fewer

than that number. The left half is expressed in percentages, the right

half in number of cases only since percentages might be misleading. Left

hand table: First column is percentage of gastroenterocolitis per order;

next five columns the percentages in which each of the factors in the

headings was believed responsible; the last three columns show the

participation of each of the divisions of the intestinal tract; thus

Primates had all told 24.8 per cent. of inflammations of which 7.2 per

cent. were in stomach, 18.3 per cent. in the intestines and 8 per cent.

in the colon; obviously many had all three sections affected. Right hand

table is constructed on a similar basis except that number of cases is

quoted, not percentages, and the total is put in the last column._

════════════╤═══════════════════════════════════════════════════════

│ Percentages in orders with sufficient autopsies.

────────────┼─────────┬────┬────────┬─────────┬────────┬────────────

│Per cent.│Food│Bacteria│ Animal │Physical│Undetermined

│ of │ │ │Parasites│Objects │

│Autopsies│ │ │ │ │

────────────┼─────────┼────┼────────┼─────────┼────────┼────────────

Primates │ 24.8│ 1.8│ 4.4│ 3.6│ │ 15.

Lemures │ │ │ │ │ │

Carnivora │ 46.1│ 2.9│ 7.2│ 5.8│ .2│ 30.

Pinnipedia │ │ │ │ │ │

Insectivora │ │ │ │ │ │

Chiroptera │ │ │ │ │ │

Rodentia │ 25.│ 5.│ 2.│ 2.│ │ 16.

Ungulata │ 24.8│ 6.6│ 2.2│ 2.│ .8│ 13.2

Proboscidea │ │ │ │ │ │

Hyraces │ │ │ │ │ │

Edentata │ │ │ │ │ │

Marsupialia │ 33.1│ │ 10.│ 10.1│ │ 13.

Passeres │ 23.6│ .1│ 4.5│ 1.8│ .15│ 17.

Picariæ │ │ │ │ │ │

Striges │ 41.5│ 1.5│ 5.3│ .7│ │ 34.

Psittaci │ 36.6│ .3│ 10.7│ 3.7│ .15│ 21.8

Accipitres │ 40.7│ │ 4.5│ │ .5│ 35.7

Columbæ │ 17.8│ │ .6│ 3.│ .6│ 13.5

Galli │ 38.6│ │ 5.3│ 19.6│ │ 13.7

Hemipodii │ │ │ │ │ │

Fulicariæ │ │ │ │ │ │

Alectorides │ │ │ │ │ │

Limicolæ │ │ │ │ │ │

Gaviæ │ │ │ │ │ │

Impennes │ │ │ │ │ │

Steganopodes│ │ │ │ │ │

Herodiones │ │ │ │ │ │

Odontoglossæ│ │ │ │ │ │

Palamedes │ │ │ │ │ │

Anseres │ 29.6│ .3│ 4.4│ 2.3│ .6│ 22.

Struthiones │ │ │ │ │ │

Crypturi │ │ │ │ │ │

────────────┴─────────┴────┴────────┴─────────┴────────┴────────────

════════════╤════════════════════════╤════════════════════════════════

│sufficient autopsies. │Number of cases in orders with under 100 autopsies each.

────────────┼───────┬──────────┬─────┼────┬────────┬─────────┬────────

│Stomach│Intestines│Colon│ │Bacteria│ Animal │Physical

│ │ │ │Food│ │Parasites│Objects

│ │ │ │ │ │ │

────────────┼───────┼──────────┼─────┼────┼────────┼─────────┼────────

Primates │ 7.2│ 18.3│ 8.│ │ │ │

Lemures │ │ │ │ │ 8│ 2│

Carnivora │ 21.│ 41.│ 6.6│ │ │ │

Pinnipedia │ │ │ │ │ 1│ 1│ 1

Insectivora │ │ │ │ │ │ │

Chiroptera │ │ │ │ │ │ │

Rodentia │ 7.│ 20.5│ 3.5│ │ │ │

Ungulata │ 9.1│ 20.│ 2.5│ │ │ │

Proboscidea │ │ │ │ │ │ │

Hyraces │ │ │ │ │ │ │

Edentata │ │ │ │ │ │ │

Marsupialia │ 22.│ 21.│ 3.5│ │ │ │

Passeres │ 1.2│ 22.│ 3.│ │ │ │

Picariæ │ │ │ │ 1│ 10│ 4│

Striges │ 6.│ 40.│ .7│ │ │ │

Psittaci │ 1.7│ 35.4│ 1.3│ │ │ │

Accipitres │ 5.2│ 39.│ 1.│ │ │ │

Columbæ │ 4.5│ 13.5│ .7│ │ │ │

Galli │ 2.6│ 21.6│ 19.6│ │ │ │

Hemipodii │ │ │ │ │ │ │

Fulicariæ │ │ │ │ │ 6│ 1│

Alectorides │ │ │ │ 1│ 1│ 2│

Limicolæ │ │ │ │ │ │ │

Gaviæ │ │ │ │ │ 1│ 1│

Impennes │ │ │ │ │ │ │

Steganopodes│ │ │ │ 1│ 1│ │

Herodiones │ │ │ │ │ 1│ 3│

Odontoglossæ│ │ │ │ │ │ │

Palamedes │ │ │ │ │ │ │

Anseres │ 2.5│ 27.7│ 6.6│ │ │ │

Struthiones │ │ │ │ │ 7│ │

Crypturi │ │ │ │ │ │ │

────────────┴───────┴──────────┴─────┴────┴────────┴─────────┴────────

════════════╤═════════════════════════════════════════════════════

│Number of cases in orders with under 100 autopsies each.

────────────┼────────────┬───────┬──────────┬─────┬───────────────

│Undetermined│Stomach│Intestines│Colon│ Total Animals

│ │ │ │ │ Showing

│ │ │ │ │Gastroenteritis

────────────┼────────────┼───────┼──────────┼─────┼───────────────

Primates │ │ │ │ │

Lemures │ 13│ 4│ 19│ 3│ 23

Carnivora │ │ │ │ │

Pinnipedia │ 8│ 7│ 8│ 1│ 11

Insectivora │ │ │ │ │

Chiroptera │ 2│ 1│ 1│ │ 2

Rodentia │ │ │ │ │

Ungulata │ │ │ │ │

Proboscidea │ 1│ │ 1│ │ 1

Hyraces │ 2│ │ 1│ 1│ 2

Edentata │ 2│ │ 1│ 1│ 2

Marsupialia │ │ │ │ │

Passeres │ │ │ │ │

Picariæ │ 24│ 5│ 36│ │ 39

Striges │ │ │ │ │

Psittaci │ │ │ │ │

Accipitres │ │ │ │ │

Columbæ │ │ │ │ │

Galli │ │ │ │ │

Hemipodii │ │ │ │ │

Fulicariæ │ 8│ 1│ 15│ │ 15

Alectorides │ 10│ 2│ 13│ 3│ 14

Limicolæ │ 1│ │ 1│ │ 1

Gaviæ │ │ │ 2│ │ 2

Impennes │ 3│ 1│ 3│ │ 3

Steganopodes│ 8│ 1│ 10│ │ 10

Herodiones │ 25│ 1│ 24│ 6│ 29

Odontoglossæ│ │ │ │ │

Palamedes │ 1│ │ 1│ │ 1

Anseres │ │ │ │ │

Struthiones │ 14│ 8│ 20│ 3│ 21

Crypturi │ 1│ │ 1│ │ 1

────────────┴────────────┴───────┴──────────┴─────┴───────────────

THE TABLE.

Our records have been analyzed from the standpoint of diagnosis and the

most probable cause. The first will be taken up in discussing each of

the orders. The probable causes are divided into food, bacteria, animal

parasites, physical objects and undecided, in other words a

classification based upon the most prominent or definite evidences as

seen at postmortem combined when possible with antemortem observations.

When findings were inconclusive or contradictory, cases were called

undecided, naturally a very large group. Fermentative processes in the

presence of obviously undigestible material, are classified with food as

a cause. When evidences of septicemia existed in absence of the other

factors, it is held that bacteria were responsible. Cases were grouped

under animal parasites when these were the most definite findings.

Physical objects are relatively unimportant and self-explanatory. To the

etiological chart there are appended columns intended to show the

percentage or case incidence of the disease of the grosser subdivisions

of the gastrointestinal tract which indicate in a general manner what

part of the tube in the various orders is most susceptible to disease.

While of course conclusions must be drawn with great caution, there can

be little doubt, for example, that carnivores and marsupials have more

gastric disease than any other order, and that the high place for the

colon is held by the gallinaceous birds. This charting was suggested by

the work of Dr. Raymond Pearl upon statistics, wherein he takes as a

basis of classification the part of the body which succumbs to disease-

producing organisms or from which a disease starts. It cannot be stated

that there is a clear cut relationship between enteritis and the

expectancy of life.

MAMMALIA.

The PRIMATES as an order have their share of inflammations of the

gastrointestinal tract and present points of interest. Acute digestive

disorders succeeded by acute dilatation of the stomach, or in less

fermentative cases by acute catarrh of the intestine, are not at all

uncommon. The reason for this is not discovered by reviewing the diet

and manner of feeding. The buccal pouches, distensible esophagus, the

freely movable stomach, and relatively elastic gastric wall would seem

to permit of very considerable dilatation to accommodate the large

quantities which the monkey sometimes crams into himself. Nine fairly

acceptable records of gastric overfilling exist and two of them seem to

have been followed by tympanites sufficient to embarrass respiration, in

one case there occurring an acute cardiac dilatation with myocardial

degeneration. The animals give no symptoms of this condition and in the

last case cited the beast, while old, ate well and was not distended the

evening before death.

When acute gastritis exists (twenty cases) the animal seems uneasy but

does not vomit. On one occasion I was called to see a monkey which was

retching and seemed in pain. Lime juice was offered and taken, followed

by gentian and cardamon, which seemed to give some benefit. Somewhat

later this was repeated in another case, but observations where this

might be useful are rare.

The pathology of gastric conditions offers little to contrast with that

of man. The enormous distensibility of the fundal pouch often suggests

to the observer the rumen of ungulates. Acute gastritis of one kind or

another and acute catarrhal enteritis are the most common lesions noted

in the Primates. Involvement of the intestine or colon need not carry

with it an increase of signs of illness, although at times one will see

an evidently sick animal with diarrhœa. Anatomically the lesions are

commonly restricted to the stretches of gut _above_ the ileum, it being

rather rare that this division or the colon is affected. Pathologically

the lesions are catarrhal with definite involvement of the follicles in

about one-third of the cases. In this order toxic and pseudomembranous

forms are quite rare and ulcerative lesions uncommon. Colonic disease as

a sequel to inflammation higher up is sometimes seen in the follicular

varieties, but takes a minor place compared to amœbic dysentery of which

we have had several cases; this will be discussed under a separate

heading. Degenerative disease of the skeleton is almost always

accompanied by a low grade of enteritis but not necessarily gastritis or

colitis. The pallor of the mucosa, while at times striking, may be

relieved by follicular spots and petechia or pigmentation. Often,

however, animals suffering from osteomalacia and rickets come to their

end by an acute inflammation of the gut tract.

The bacteriology at our disposal allows no conclusions. Aside from a

case probably due to Ps. fluorescens and one with colon bacillus

abscesses in the liver, no reliable data are at hand.

Reference to Table 11 reveals the fact that among orders with sufficient

autopsies to permit percentages, the alimentary tract in monkeys is in

the group of low figures, that the intestinal section is relatively more

often affected, and that the colon is more often diseased than in other

mammalian orders, and is exceeded only by the gallinaceous birds.

The LEMURES, of which we have eighty-six autopsies, do not differ much

in anatomy from the Primates, however greatly they disagree in habits

and outward appearance; their diet is the same. Clinically the slothful

behavior of a normal lemur probably obscures symptoms and signs of

illness, for our antemortem notes with the exception of a few

observations of loose stools, fail to offer a lead as to diagnosis. This

order has a large incidence (twenty-three cases) of gastroenteric

conditions as shown in Table 11, but some explanation of the figures is

deserved. In the first place, only one case of acute gastritis occurred,

and this was apparently a part of a general infection, and if induced at

all by food this was only secondary. Indeed as one reviews the records

it does not seem that the lemurs are easily disturbed in their gastric

digestion. Acute and subacute inflammations from bacterial action seem

definitely more prominent since they take the catarrhal, follicular and

deep submucous form and are frequently associated with generalized

infectious processes. One amœbic case was observed and there was another

in which a heavy cestode and nematode infestation seemed to have paved

the way for bacteria.

CARNIVORA.

The food of this order is received into the fundal part of the stomach,

the distensible but normally capacious left and superior two-thirds of

the organ. The general shape of the viscus, that of a gourd, permits a

fairly sharp separation of the fundal and pyloric sections, so definite

indeed that the pathology of the two parts was studied. The intestines

vary in length, but in the land carnivores are relatively short, narrow

in lumen and rich in wall. A cecum, or at least a blind end of the large

gut made by the insertion of the small intestine above the tip of the

colon, is suggested in all families, although, as in the bears, it may

be quite insignificant or rudimentary. Theoretically no stasis should

occur at this point. The colon is short in all carnivores and, like the

small gut, with a heavy wall. The comparative simplicity of the

carnivorous gut tract, the ability of many of these animals to disgorge,

the suggestion of high resistance of the upper end of the tract to

infection and the ease with which diarrhœa can clear out the tube, would

seem to warrant the expectation that inflammation would not be serious.

Such, however, is not the fact for, on the contrary, they have shown a

higher incidence than any other order for which we have adequate

comparison. Anatomically considered their stomach occupies the second

place in vulnerability, next to the marsupials, and their intestines the

highest place; this indicates of course that combined gastric and

intestinal disease has often occurred. Involvement of the colon occupies

the second place, in ordinate susceptibility, being exceeded only by the

monkeys, due to heavy parasitic infestation, but would occupy the first

place were the eleven amœbic dysenteries in monkeys subtracted from

their total, a subtraction which might be allowed since it represented

an epizoötic outbreak.

Etiologically considered, it would seem as if the influence of incorrect

feeding were of little importance, and from one standpoint this is

probably the case. Acute fermentative or irritative processes are not

common at all, while more inflammatory pictures, catarrhal, erosive or

ulcerative, are the rule. There is another phase to the term incorrect

food, that is incorrect in its cleanness. During 1912–15 there was an

increasing mortality among the cats and dogs fed upon horse meat, mutton

and fowl heads. Early in 1916 the butcher shop was reconstructed and

thoroughly cleaned and covered galvanized pans supplied in which to

transport the food; these pans were scrubbed and scalded after use.

Since that time, infections inflammations of the stomach and intestines

have shown an ever increasing downward incidence, which result, there

having been no material changes in other directions, I do not hesitate

to ascribe to the improvement of butchering and dispensing engineered by

Dr. W. B. Cadwalader.

Helminths seem to be of importance in this order both by reason of the

percentage of autopsies in which they presented the most probable or at

least most suggestive cause and because uncinaria and strongylus have

been seen attached to the wall and a large bulk of known irritative

cestodes have occupied the lumen. Physical objects, stones, bones, wire,

may cause irritation enough to activate bacterial action or may actually

penetrate the wall; the latter action is well known. In so far as

practical application of this is concerned, it teaches to feed whole,

unsplintered or ground bone.

The distribution and character of pathological lesions according to the

region of the stomach is what might be expected from the shape and

physiology of its parts. True inflammatory processes are best, and in

some cases only seen in the pyloric half of the viscus, while the

changes in those few cases believed to be fermentative or irritative in

nature were largely confined to the fundus. Dilatation of the latter

part may be understood because there the muscular coats are about equal

to the mucous in thickness and one-half the width of those at the

pylorus, but why inflammatory processes should not be so developed in

the fundus is not clear unless the greater availability of mucus

protects the secreting wall. Not only does acute inflammation reach its

most definite form in the second part of the stomach, but the irregular

pigmentation, mammillated overgrowth and atrophy or ulceration of

chronic disease are likewise best seen in this part.

Acute enteritis, of all varieties, is seen more beautifully in

carnivores than in any other order of mammals, and nowhere can it be

studied better. Its gross appearance is that of the text-book and its

minute character even more instructive. I have used a slide of acute

catarrhal enteritis in a lion for the illustration of this lesion for

the _Text-book of Pathology_ by Doctor Stengel and myself. However, as

is known to all who have paid any attention to enteritis, the postmortem

findings are usually much less definite than clinical observations would

warrant one to expect. The Carnivora not uncommonly show intestinal

congestion, mucous membrane swelling without edema or opacity,

congestion of the spleen, cloudy swelling of the liver and kidneys and

perhaps mesenteric lymph node edema. This picture we have viewed as a

toxic affair of some sort or a bacterial infection not yet far enough

advanced to produce catarrhal or ulcerative enteritis and septicemia. In

such cases the carnivorous intestinal mucosa offers instruction. The

epithelium is vacuolated or fringed on the free edge or may be missing

altogether. In the depths mucus formation is very active, and where it

is going on, round cells seem attracted, collecting in groups in the

villus or in the subjacent submucosa. Perivascular round cell increase

may be noted. Plasma cells and granular eosinophiles are common, but I

cannot state how important the latter are in the general picture because

of the frequency of parasites in carnivores. The central vessel of the

villus and the arterioles of the submucosa are injected. Lymph follicles

may or may not be enlarged, but if so usually fail to show a germ

centre.

Colitis alone is not common in this order, but as an extension process

or involvement at the same time as the upper levels it occurs

occasionally. The only fact I wish to record and one which I would

emphasize because of having seen it recently in a human case of chronic

colitis, and since it does not appear important to systematic writers,

is superficial blood supply. The capillary network of the colonic villi,

while rich, is in the form of a fine plexus just under the epithelium.

In the cases studied these vessels become quite distinct and possess

much more definite walls, often bordered by mononuclears, while

connective tissue is more evident at the bases of the villi and deeper.

This may help in deciding the existence of a colitis.

Bacteriologically the most instructive experience to report is the

discovery that a small outbreak of enteritis among small Carnivora,

chiefly cats, fed upon fowl heads was due to Bact. paracoli, or at least

this organism was found in the intestinal mucosa, spleen, and heart’s

blood of three cases. The type of enteritis was hemorrhagic and

follicular. There was also a case of septicemia apparently emanating

from enteritis due to Bact. suipestifer in a lion (_Felis leo_). These

facts bring strongly to attention the modern teaching that meat

poisonings of the Gärtner type are to be considered as infectious and

not of the so-called ptomaine group.

PINNIPEDIA, while related closely to the Carnivora, are grouped in a

suborder in our classification and because of their restricted diet are

treated here in a separate paragraph. The tract is peculiar in the

strong tubular stomach sharply bent upon itself, the great length of the

small gut (upwards of a hundred feet in some genera), and the practical

absence of a cecum. Pathologically speaking, the most striking lesion of

these animals is ulcerative gastritis, a process usually most marked

along the posterior-superior surface, but not confined thereto. Upon

inspection the gastric mucosa, normally supplied with low regular rugæ,

is much distorted by swellings upon the top of which are irregular

ragged ulcers with rounded elevated but not frayed margins. The density

of the edges indicates much infiltration of the deep mucosa and

submucosa; this can be confirmed by microscopical examination. One

attempt to study this gastritis bacteriologically was fruitless.

Sections of one case showed streptothrix-like masses while in another

case bacterial colonies and yeast-like bodies were found in adjacent

lymph nodes. The genesis of this condition might lie in injury by fish

fins or by foreign bodies, of which large numbers are found at times (a

pint and a half of stones, marbles, and sticks were found in one

stomach). Gastritis has been the starting point of septicemia on two

occasions, and three times an acute exacerbation or new implantation of

infection occurred, with extension into the intestine. It is interesting

that all the deaths of Pinnipedia with gastroenteric conditions occurred

in the winter months.

INSECTIVORA are represented by two common European Hedgehogs. In one

there were three shallow but shelving ulcers in the stomach which had

bled sufficiently to weaken the animal; free blood was found in the

intestine. The other specimen was diagnosed at postmortem as having

catarrhal enteritis involving nearly the whole small gut, but

histological section did not confirm this.

As one descends the zoological scale the first gastrointestinal tract

prepared for the nutritional care of bulky food is to be found in the

RODENTIA. This order presents a great variety of shapes and arrangements

of the stomach, but the outstanding feature, with very few exceptions

(cf. spermophiles), is the development of the cardiac and fundal

divisions ostensibly for the reception of a large bulk of coarse food to

be digested at leisure. Some genera like the hamster (_Cricetus_) have a

stomach closely resembling the ruminants, while that of the spermophile

suggests the equine stomach. The pyloric end, variable in many ways,

greatly resembles the abomasum. So too the duodenum is large, loose and

distensible while the copious small gut ends in a very large cecum,

shaped at times in a manner which has led to the term “colonic stomach.”

The colon is variable and not always supplied with longitudinal bands

and sacculations.

In regard to incidence of gastrointestinal disease, rodents occupy a

middle position in the table. The stomach seems a vulnerable section of

the tract. Dilatation of the left hand section is common, due, to all

appearances, to fermentative processes which have as a result the

softening of the mucosa so that even immediately after death it will

separate almost entirely. In these cases the pyloric part need not

participate but may remain flat, smooth, soft and pink. This condition

is slightly more common in the compound than in the simple stomachs. In

some of this order, especially rats and cavies, there is a fermentative

gastroenteritis expressed by injection and edema of the pylorus and

duodenum, and much frothy mucus. It was at first thought that some

relation might exist between this condition and the absence of the gall-

bladder, but it occurs in varieties possessing this structure. The

reaction of the intestine to irritation in this order is peculiar in two

ways, the occurrence of mucus and the activity of the lymphatics. In all

the inflammations from and including the stomach to the cecum, mucus is

conspicuous. At times it is thin or loose and mixed with contents, while

at others it forms a relatively close covering for the mucosa almost

like a false membrane. Rodentia are peculiar in the promptness and

clearness with which the follicles of the intestinal wall and mesentery

enlarge in inflammation. They appear as pale, well outlined or diffuse

opacities in the wall or as distinct plaques prominent on the surface.

The PROBOSCIDEA are represented by one Elephant (_Elephas indicus_), in

which a mild catarrhal change was seen in the middle stretches of the

small intestine. This was of little importance as a cause of death,

there being several other diagnoses, and was probably a terminal affair.

HYRACES, of which we have a total of seven examples, present two mild

involvements of the intestine but none of the stomach. It would appear

from the records that the intestinal condition had little to do with the

death of the animals, and unfortunately no microscopic slides were made.

Because of the curious formation of the large gut, notes of both ceca

were made in one case, and can be condensed as follows: “The upper or

anterior cecum presented a shaggy pearl gray mucous covering, closely

attached to the mucosa. This cavity and the posterior ceca were packed

with dry crumbling feces. Small thin-walled cysts were seen in the tips

of the lower ceca. Duodenum was congested and mucosa swollen. Stomach

contained dry, poorly digested food. No parasites were found.”

The EDENTATA are represented by an Armadillo (_Tatu novemcinctus_) and

an Anteater (_Myrmecophaga tridactyla_.) The former had a prolapse of

the rectum accompanied by colitis but it is impossible to decide the

priority of the two conditions since the former is known to have existed

long enough to have permitted the latter to develop. The Anteater had a

distinct mucocatarrhal enteritis in which bacteria played a part since

involvement of the liver, spleen, kidney and lymph nodes also existed.

The beast was in good condition upon arrival, but did not become

accustomed to the proffered diet, and was distinctly anemic at death.

The UNGULATA, so-called for their hoofed and horned character, are also

associated anatomically by the construction of their gastrointestinal

tract. However, the order of the list as given on page 44 does not

represent their historical development nor does it accord with

anatomical arrangement of the tube under discussion. The last three

families of Artiodactyla are perhaps the simplest in the construction of

this tube, or at least take an equal place with the Perissodactyla,

while the remaining families of the former suborder have a complex tract

of generally similar architecture. This whole order has, however, an

alimentary tract anatomically suited for the consumption of bulky

vegetable stuffs and shows an attempt at adjustment between the food,

the methods of mastication, the area of digestive surface, and the bulk

necessary for nutrition. The number of factors opened up by the many

variations between this complex tract and that of the carnivorous simple

tract is so great that I shall attempt only to contrast the anatomy and

pathology of the simpler ungulate tracts and the complex ruminant

apparatus.

The simpler gastrointestinal tract is possessed by the Perissodactyla,

and by the following families of Artiodactyla, the Phachocœridæ, Suidæ

and Tayassuidæ. This consists of a stomach with a single cavity (some

Peccaries have partitions but no true septa with strict histological

differences) divided into esophageal, cardiac, fundal and pyloric areas,

dependent upon the nature of the lining epithelia and the absence or

presence of glands, as well as the nature of the tubules. The duodenal

section is ample and may be sacculated while the intestines are small in

calibre and rather sturdy in wall. The cecum is relatively very large,

well supplied by longitudinal bands and sacculations; the colon is

relatively short but quite capacious and sacculated.

The ruminants and other remaining members of the Artiodactyla have a

compound stomach suited to the separation of coarse and fluid foods and

the retention of water, and so arranged that boluses of different

densities are distributed as needed. These divisions are histologically

as well as grossly different. The first three, comparable to the

esophageal section of the simpler stomach, are reservoirs or channels,

while the fourth or true digestive section, is divided into areas

corresponding to fundus and pylorus, possessing the appropriate type of

gland. The duodenum in this group is narrow, as is the rest of the small

gut, and has delicate walls. The cecum proper is short and of variable

width, but never as great as in the group first discussed, while the

colon, an intricately wound tube, is narrow and very long. Certain of

the first group (Peccaries) have a colon of this type, but it is not so

complicated as in true ruminants.

These complications seem designed to permit of a long retention of

coarse food of low nutritive value per bulk for a time sufficient for

full digestion; reverse adaptation of large size of stomach and colon

may be explained on the same basis. Let us now examine these two groups

to discover their pathological reactions and the nature of the lesions.

TABLE 12.

_Showing the Percentage Incidence of Various Forms of Inflammation in

the Alimentary Tract of Ungulata._

══════════════════════════════════╤═════════════════╤═════════════════

Lesion │ Group A │ Group B

│ Perissodactyla │ Ruminants and

│ and Swine, Wart │ Relatives Per

│ Hogs, Peccaries │ cent.

│ Per cent. │

──────────────────────────────────┼─────────────────┼─────────────────

Acute fermentative gastritis │ 18.│ 2.1

All other forms of gastritis │ 16.3│ 5.

Acute toxic or fermentative │ 1.6│ 2.3

enteritis │ │

All other forms of acute enteritis│ 1.6│ 8.4

Chronic enteritis │ 0.│ 1.9

Colitis and typhlitis │ 0.│ 3.1

──────────────────────────────────┴─────────────────┴─────────────────

Ungulates as a class stand in a position equivalent to the Primates in

the incidence of gastrointestinal diseases. They show a conspicuous

percentage of cases apparently due to incorrect food and, coupled with

this, a high percentage of gastric involvement, being exceeded in this

respect by the marsupials only (there is an adequate reason for this—see

below). Cases ascribed to bacterial or parasitic agents are not

numerous. Analysis of the records of the two groups discussed above

brings out some interesting facts. Consultation of Table 12 shows

percentage comparisons, based on the number of autopsies, of lesions in

the various sections of the tract. Group A, that with the simple stomach

and the short capacious colon, is represented by forty-four specimens,

while Group B embraces 321 animals. Perhaps the use of these two widely

differing figures for comparison is open to some objection which might

be final and decisive were not the figures so definite. At a glance one

can see that Group A has involvement more marked high in the tract while

Group B has more disease in the intestine and colon. Certainly gastritis

is more common (five times) in the A than in the B group, while

enteritis is more common in B (over three times). No case of chronic

enteritis or of involvement of the colon is recorded in animals with a

simple stomach and a wide hind-gut. This may be read either in terms of

vulnerability of the stomach or in the degree of resistance of the

respective groups.

Consideration of the local factors of the stomach brings to light at

once the fact that incorrect food entering the simple stomach could

attack the softer, less resistant glandular section of the fundal and

pyloric areas whereas the rumen and psalter of the compound organ, with

their stratified epithelium devoid of glands, act as barriers or as

places where detoxication of irritants might take place. In both groups

bulky food is packed to the left, the esophageal and cardiac section in

the simple form, the rumen in the compound. Soft or liquid food may pass

into the psalter and abomasum of the ruminant stomach almost directly

since it has not the force or bulk to push aside the valve-like fold of

wall at the junction of esophagus, rumen and reticulum. For this reason,

if for no other, the character of soft food supplied to this order must

be unexceptionable.

It has not been possible to follow out the layering of diets as

Scheunert did when showing the course of various foods before they are

mixed at the beginning of the pyloric compartments. We have seen two

cases in ruminants which seem to indicate that soft food had passed into

the right side cavities of the stomach, there to cause irritation, while

the rumen remained quite normal. It seems, however, accepted by

veterinarians that excessive soft food may be followed by trouble in the

digestive stomachs, while excessive dry food may cause distention of the

left hand sections. So far as I know, the relative incidence of gastric

disorders in the above outlined groups has not been pointed out before.

The pathological types of gastroenteritis do not present many unusual

features. Simple injection of vessels during digestion seems more

evident in this than any other order, while mucus production seems less

marked. The mucosa of the reservoir portions may, in simple overfilling

and fermentative distention (gastric tympanites), be quite normal or

dull red; when active fermentation has occurred it may be digested and

peel off. More or less true inflammation as seen in the digestive

stomachs is definitely better expressed in the compound ruminant organ

than in the simple equine variety where congestion and edematous

swelling with hemorrhage form the usual picture. True catarrhal changes

both gross and minute, are often well seen and ulcerative lesions are

not uncommon; ulcers are unusual in the simple stomach. These statements

hold good also for the small intestine. Enteritis affects the duodenum

and jejunum more in the Perissodactyla and swine than in the ruminants.

Ungulata do not react with hyperplasia of the mural lymphatics as do

many other orders, but the swelling of the mesenteric nodes is often

noteworthy. As might be expected this is more definite with catarrhal

changes and therefore best seen in the ruminants. In the colon, however,

the solitary follicles are often quite prominent in simple inflammation.

Histologically the greatest changes seen in this order are superficial

degenerations with mononuclear increase in the deep submucosa, mostly

arranged in perivascular fashion. The villi do not contain the large

number of cells seen in the Carnivora.

MARSUPIALIA.

Consultation of the figures for this order in Table 11 arrests attention

at once because of the peculiar percentages found under the detailed

factors. Thus food is of no moment as a disturber of the alimentary

tract, while bacteria and parasites are high in importance. The gastric

segment is more often attacked than any other portion and slightly more

often than in the nearest order, Carnivora. These unusual figures

deserve explanation, to which purpose it will be necessary to consider

the anatomy of the organ and to discuss why bacteria and parasites stand

so high in etiology.

Marsupials are divided into six families in our classification (see page

44) which in regard to their diet, range from largely carnivorous (the

first two) through those choosing mixed insects, fruits and vegetables

(the second two) to those eating vegetables and grain (the last two).

The stomach of these animals does not vary exactly according to their

diet, the first four, opossums, dasyures, bandicoots and wombats,

possessing an organ closely similar in outline and construction and

resembling the carnivorous variety, while the phalangers and kangaroos

have a stomach entirely different from the first four although somewhat

similar to one another. The first group has a round or irregularly

elliptical organ with the esophagus and pylorus close together along the

lesser curvature. The wombats have a bank of glands surrounded by a

capsule, near the cardia. The stomach of the first four animals is

divided into cardiac, fundal and pyloric parts by the construction of

their mucosa, the first mentioned division being a high, rounded pouch,

rumen-like, well to the left. The phalanger’s stomach is more elongated,

the two openings well separated and a fissure is found in the right end

of the lesser curvature which serves to separate the pyloric part from

the rest. The Macropodidæ all have a stomach resembling the human colon

in being elongated, with longitudinal bands gathering it into

sacculations. There is a distinct esophageal section to the left with a

blind sac suggesting an ungulate rumen, a long tubular fundal, and a

sacculate pyloric division.

The small intestine of the order starts with the opossums as a stout

muscular and mucous tube fitted for meat eating, but as one proceeds to

study the families downward in the list this tube becomes more delicate

and longer. In the first two families the cecum is rudimentary and the

colon very short as in cats, but the length and capacity of these parts

increase through the bandicoots and wombats until in the strict fruit,

vegetable and grain eaters, phalangers and kangaroos, the cecum is long

and capacious and the colon relatively long and roomy.

TABLE 13.

_Showing the Incidence of Gastroenteric Disease in the Two Forms of

Marsupial Intestinal Tracts._

═══════════════════════╤═══════════════════════╤═══════════════════════

│ Group A │ Group B

│Carnivorous Stomach and│Herbivorous Stomach and

│ Intestines 103 │Intestines 73 Specimens

│ Specimens Per cent. │ Per cent.

───────────────────────┼───────────────────────┼───────────────────────

Acute gastritis │ 9.6 │ 15.

│ Bacteria Verminous │ Bacteria Verminous

Chronic gastritis │ 0. 13.6 │ 5.4 0.

Acute enteritis │ 2.9 │ 1.5

Colitis incl. typhlitis│ 1.9 │ 4.3

───────────────────────┴───────────────────────┴───────────────────────

Table 13 contains an analysis of the forms of gastroenteritis as they

were described in the two groups of tracts, that resembling the

carnivorous, that similar to the herbivorous intestinal construction,

and according to the factor believed to be responsible. In the first

group gastritis of an acute nature occurred in 9.6 per cent. of the 103

specimens. They were chiefly catarrhal in character and seem for the

most part secondary to verminous infestation; at least six of the ten

cases were associated with parasites. The process microscopically is

catarrhal and deeply infiltrative. Group B has a high incidence of

gastritis and here the evidence of bacteria or toxins is quite plain.

Several of the cases were in animals showing also Kangaroo disease of

the jaw with pneumonia or septicemia; the gastric lesion of

streptothricosis will be described under that heading. The character of

gastritis without jaw disease is somewhat different from that with it.

Pathologically the process is a congestive and superficially necrotizing

affair, forming upon the tips of the folds, small gray erosions or flat

shallow irregular ulcers, which upon histological study consist of loss

of tissue of the mucosa and some deep congestion with round cell groups

but no reaction deep in mucosa or submucosa. True catarrhal inflammation

has occurred, but not like in the opossums.

Chronic gastritis in the simple stomachs is almost exclusively in

opossums harboring _Physaloptera turgida_, a worm which fastens itself

more or less firmly in the mucosa and probably, with the assistance of

bacteria, causes sufficient irritation to produce a hypertrophic change

in the deeper layers and a destruction of the glands where it holds and

a distortion of those nearby. One is reminded that Fibiger found

spiroptera to be responsible for adenocarcinoma in rats; no tumor

formation has been found in these animals, although one opossum with

such a stomach had an adenocarcinoma mammæ. Small hemorrhagic spots may

occur in the deeper layers, possibly where the worms have bitten. The

rugæ are irregular or interrupted by knobs and papillæ.

Group B, stomachs showing chronic change, were all kangaroos. The three

cases resembled the infiltrating necrotizing lesions as discussed under

ulcers (page 175). The process showed an infiltration of the subsurface

tissues with a gray slough over the densest part. The mucosa as a whole

was irregularly rugous and spotted with red gray areas.

Altogether one gets the impression that in the simpler stomach, reactive

inflammation is most prominent, while in the colonoid stomach

degeneration is greater than reaction.

Intestinal lesions in marsupials are not common and not peculiar except

in that they carry out the pathological reaction as seen in the stomach.

The carnivorous intestine shows frank catarrhal changes, the herbivorous

presents congestions and superficial necroses. These two groups then

follow the descriptions as already given for carnivores and ruminants.

The colon presented in the first group, simple catarrhal or follicular

change. In the second division the lesions resembled those in the

stomach; they were only once of the three instances associated with

streptothricosis.

AVES.

The class Aves has been treated in the chart precisely as have the

mammals, but it is not possible to make the accurate diagnoses or to

separate groups of lesions according to anatomy as was done for the

latter class. Upon the average there is more gastroenteritis among birds

than mammals, but when looking for an explanation of this, it was

unfortunately necessary to enter in the “undecided” column of Table 11 a

very great number of cases. This column would be greater relatively were

it not for the parasites in parrots and gallinaceous birds, the entries

for which are high. Besides this fact and that the owl stands at the

top, the pigeons at the bottom of the list numerically, no further

general statements are allowable. There are several orders with high

values among those of which insufficient autopsies are at hand to cast

percentages.

The avian alimentary tract seems to have developed according to the

character of food the different varieties of birds consume if one may

judge by the construction of the bill, the gastric musculature and the

intestinal wall. Zoological classification has only secondarily

considered this point, it being made incidental to the habits and

habitats of birds. For this reason the orders as outlined on pages

44–46, placed as they are in historical evolutionary position, represent

with few exceptions groups which have differing diets and, by the same

token, differing gastrointestinal tracts. Classifications based upon

habits of life (Raptores, Cantores, Natores), prove likewise too broad

or too heterogeneous, while systems making character of food the chief

criterion though apparently correct in reasoning and helpful in certain

orders, (Accipitres, Galli) are found to present copious exceptions;

moreover we are imperfectly informed of the exact diet that many

families require or resort to in absence of their preferred food. I

shall therefore discuss the chief diseases and distributions according

to our classification, preceding the discussion by a brief résumé of the

anatomical peculiarities of the avian alimentary tube.

The first digestive burden falls upon the proventricle where the

principal juices are secreted while the muscular stomach or gizzard

assumes the duty of gastric mastication. The lateral muscular bellies of

its heavy wall grind the food and mix well the gastric juices. Its

mucosa probably supplies only lubricant. In birds whose food is hard,

corn and the like, this grinder is supplied with a dry horny internal

layer, while a thick, moist, soft, epithelial surface is sufficient for

carnivorous birds. All kinds of gradations exist between these extremes.

The mucosa of the proventricle is always soft, but quite deep to permit

the placement of compound tubular glands.

The relation of size of these two parts is subject to many

variations.[22] The proventricle is larger proportionately in meat

eating, fish-eating and fruit eating birds, the gizzard having the

greater size in granivora and insectivora. In certain birds the mucosa

of the two is separated by a very soft thin zone, an important fact in

Psittaci since at this place spiroptera seem to penetrate to the

glandular layer of both organs.

The duodenum begins in practically all birds, from a spherical cavity at

the pyloric end of the gizzard, to be accredited anatomically to both

sections. It passes downward, forms a long loop enclosing the pancreas,

its distal end lying under the liver and near the gall-bladder. Near its

end it receives the major bile and pancreatic ducts; smaller ducts from

the liver and pancreas may enter near the pylorus or elsewhere along the

loop. The small intestine is usually simple in its coils, but in the

birds that eat grain, grass and greens, may be long and complicated. So

too the colon, usually a very short segment, may be increased in the

just mentioned group while the ceca are only of any considerable length

in herbivorous birds. The length of the ceca is, according to Owen,

related to the availability of food and the need the bird may have for

exhausting the nutritive value of it. In carnivorous birds as in similar

mammals, the whole gut, but especially the hind-gut, is very short and

the ceca small or absent. But so they are in picarian birds which are

chiefly herbivorous, but may eat meat.

GASTRITIS.

The double-muscle stomach, that with the two lateral plates and tough

epidermal internal coating, is seldom the seat of disease. An excess of

greens in the diet sometimes seems to soften or macerate the lining,

while an excess of pebbles may cause erosions. Upon severe irritation

this internal layer assumes the appearance of tanned leather and may

crack. The proventricle of such a gizzard seems rather resistant to

disease, particularly one would say, to infective processes, for

catarrhal or ulcerative inflammation is uncommon. The saccular stomach

with uniform muscular walls continuous with those of the proventricle,

such as is seen in raptatory birds and parrots, offers a somewhat

different picture. The internal membranes of these organs are definitely

softer, seeming to swell with great ease, and the glands themselves are

smaller both at the fundus and outlet, a construction which may favor

their closure by swelling from simple congestion and edema. Catarrhal

and ulcerative processes are definitely more common in such organs than

in the first type or true gizzard.

ENTERITIS.

Enteritis of all orders is most outspoken in the duodenal loop, but a

determination of the lesion must be made with some care. All the signs

of intestinal inflammation—congestion, swelling and opacity, excess

mucus or mucopurulent covering—must be present to justify a gross

diagnosis of enteritis and even when these exist one fails at times to

confirm the finding by microscopical section. These changes may be

simulated by digestive activity so that it is but reasonable to demand

them all in a clear cut fashion before applying the term enteritis.

However, it is well known that cases in both human and veterinary

medicine giving a satisfactory clinical picture of this disease may fail

to show to the naked eye and under magnification the changes expected.

In the human being, the carnivore and the ruminant, the ileum presents

the most definite picture of enteritis. In the bird, the duodenum shows

the prominent lesions, and with the exception of specific diseases like

blackhead, is always involved when the smaller coil of small intestine

is affected. This is true whether the enteritis be nonspecific or be

associated with cholera of chickens, ducks or parrots.

The colon presents peculiar lesions in but few birds. Ulcerative and

necrotizing processes have been encountered in three orders, Psittaci,

Anseres and Herodiones, suggestively like the specific forms seen in the

ceca. Microscopy and one unsuccessful culture failed to reveal a mould

or protozoön. The condition appears as a gray white plaque in the

cloacal wall or it may spread up to the colon and around the urethral

orifices. At times it is superficial upon the mucosa and may be covered

by a pseudomembrane.

The chief interest in the ceca centres about enterohepatitis either of

heterakis and amœbic origin or that supposed to be due to coccidia or

Bac. scoticus. This specific form has been encountered only in Galli

(three of the four families). It has been so well described by Hadley,

Smith, Morse and Cushman that it is unnecessary to discuss it since we

have nothing to add to its pathogenesis or pathology. At a later time

some attention will be given to our experience with Quail disease. What

is more interesting from a comparative standpoint, besides having a

bearing upon blackhead, is the discovery of heterakis in the ceca, and

hemorrhage and fatty change in the liver without amœbæ or coccidia in

either place (unfortunately no bacteriology was done), in a Sebastopol

Goose (_Anser domesticus_), a bird which has ceca not unlike the

gallinaceous varieties. This is a single observation and must be treated

expectantly.

Microscopically the avian digestive tract in its various inflammatory

states presents a few noteworthy features. The primary reaction,

sometimes the only one, to irritation is injection of the vessels in the

villi or deeper mucosa. To this, however, is nearly always added a

granularity of the epithelium, without much evident mucus (goblet cell)

formation. When the epithelial degeneration is marked there appears a

round cell increase in the deep mucosa shortly followed by a similar

infiltration into the villi. True catarrhal enteritis as described for

the cats is not as common as some combination of the changes just

detailed, but when it occurs is best developed in the carnivorous avian

tract. The most striking cellular finding is the round cell of the

infiltrate. It is of the middle lymphoid size with clear protoplasm, or,

when late in the disease, may be small and so-called adult.

Polynuclears, unless eosinophilic, and endothelioid cells are rare.

The foregoing are general remarks concerning the pathology of the avian

tract, and we are now ready to discuss briefly the reactions of the

orders. I shall, however, omit mention of those in the right half of

Table 11.

Passerine birds are represented better than any other order because they

are more numerous in nature and therefore exhibited more generously in

collections. This order is not especially vulnerable as to its

alimentary tract, but this tube is often affected by tiny stones, bits

of rust from cages and by acute general nonspecific infections to which

these birds are quite susceptible. Upon many occasions intense

congestion with and without tiny hemorrhages in the duodenum are all

that can be found in the little birds and the diagnosis of enteritis is

put down. Only about one-tenth of these birds have shown more or less

definite catarrhal changes. Many birds have heavy infestation with worms

which may activate bacteria.

The Striges and the Accipitres will be discussed together because of the

similarity of their tracts and their diets. The reaction of their

gastric complex has already been mentioned and what was written there

can be extended to the intestine. The type of lesion is catarrhal and

seems to be “meat bred” although this cannot be proven. They never have

given positive heart’s blood cultures so that the disease seemed not to

be septicemic. Liver and spleen have harbored colon and paracolon

bacilli. It will be noticed that they have the highest incidence of

gastric disease.

Psittaci, birds with a tract similar to the last two but with a captive

diet of seeds, fruit and vegetables although they may eat small animals

and insects in the wild, present figures under bacteria and parasites

which explain the involvement of the alimentary organs. We have had two

acute outbreaks of what seemed to be fowl cholera, judging by the

pathology and the isolation of _Bact. gallinarum_ and we have frequent

deaths with the same gross anatomy from which bacterial isolation has

not been tried or was unsuccessful. At all events the enteritis of

parrots is often a definitely infectious affair. We have also isolated

_Bact. psittacosis_ on two occasions. Separation of the birds and

cleansing of the exhibition spaces seemed to stop the disease. The

lesions are hemorrhagic and superficially necrotizing in this group

whether or not they are septicemic. Some have also shown a follicular

appearance both grossly and minutely, one of which cases was associated

with _Bact. psittacosis_.

The effect of animal parasites is chiefly exerted, for this group, in

the proventricle where the S_piroptera incerta_ occupies the lumen and

penetrates the mucosa or burrows under the inner lining of the gizzard.

Enteritis is not especially associated with this infestation, death

resulting more from inanition than infection; some few cases have had

enteritis, others pulmonary disease.

Columbæ are not susceptible to disease in the parts under consideration.

This order seems to have some tissue resistance, for their lesions are

quite frankly catarrhal, more so than in most grain-eating birds.

The figures set against the Galli are swollen by the number of cases of

enterohepatitis of one sort or another. Extracting these from the total

leaves the order among the lowest. Their lesions are congestive and

hemorrhagic, although they may show catarrhal cases. They seem to be

able to summon mucus more readily than many other birds.

Anserine birds, though not very high in figures, present three

conditions worthy of note. In the first place, acute simple gastritis

occurs often, sometimes associated with foul green food, sometimes

without any apparent cause. From the number of times that foreign bodies

are present it seems probable that they contribute in some way.

Excessive stones and sand, bits of glass, collar buttons and the like

are sometimes found. Then the form of acute enteritis has always a

hemorrhagic tendency, at least in the submucosa, while the mucosa may be

swollen, opaque and covered with mucus. Upon histological study these

intestines show intense swelling by cellular infiltrate and

disappearance of the tips of the villi. The third observation concerns

what is apparently a subacute or chronic process although this is not

supported by microscopy. Certain birds will have a cast of mucus and

epithelial detritus rather closely adherent to the wall. Under the

microscope there may be slight evidence of chronic inflammation or there

may be little amiss. These birds have usually been large ones, and

several have come from the separate goose pens, not from the open lake

where many birds are kept.

The struthious birds deserve a word. They have had a great deal of

enteritis and mostly of infectious nature. Two instances have arisen

from bird diphtheria, one from cholera and six from what later seemed to

have been anthrax but was not diagnosed at the time. The character of

the lesions in the struthious intestine tends to be hypertrophic and

superficially erosive if not ulcerative. The changes are found with

greatest clearness in the lower duodenum and small coil.

CONSTIPATION.

Having discussed the inflammatory conditions of the gastrointestinal

tract we now come to the more or less definitely mechanical

abnormalities, whether or not they depend upon preëxisting inflammation,

and the subject of constipation will claim first attention. In the human

being this condition is the result of bad habits more than any other one

thing or all things together, I think it will be admitted. In the lower

animals perhaps no such thing as habit of defecation exists so that one

can with more certainty hold incorrect food, chronic catarrhs or

physical obstruction as responsible. Veterinarians look upon excess of

dry food and irregularity of work and food periods as the principal

causes of constipation. These factors do not hold in zoological

collections. As a matter of fact constipation is of minor importance in

this menagerie, but a certain few cases are worthy of note. It has been

mentioned in the diagnoses in only a little over 1 per cent. of the

total, and of these the records indicate its importance only ten times

(.2 per cent.); a few notes of these cases are appended. The first place

of incidence is taken by marsupials (six kangaroos and one opossum), the

second by ungulates (largely ruminants) and the third by Primates. It

will be noted that with exception of the opossum, herbivorous mammals

occupy the first places of incidence, carnivores falling well behind the

orders named. This condition is quite infrequent in birds and is usually

associated with the presence of seeds or parasites or with impaction in

the ceca.

Primates, almost exclusively feeders upon carbohydrate and soft protein

food, have shown as causes of constipation two outstanding conditions. A

low grade of colonic catarrh with excessive pouchings of this tube has

had constipation associated with it three times. One of these cases had

small coproliths in the diverticula, one other a fecal concrement in the

cecum. Another group of these cases with evidence of delayed passage of

feces shows chronic peritonitis with adhesions, one of which seems

certainly due to filaria in the peritoneal sac.

The seat of constipation in monkeys is practically always the colon. The

carnivores while occasionally showing hard fecal masses packed into the

colon, more often exhibit a constipation in the ileum. One case

presented a nearly empty colon with a long scybalum just above the cecal

valve. There is no peculiar associated pathology in the notes at my

command.

Ungulata, showing next to the highest incidence, has its stoppage

chiefly in the colon, but the lowest stretch of the ileum may contain

balls of feces. In nearly every case one finds some grade of colonic

catarrh. In two instances, there being a proctitis, it seemed as if the

animal voluntarily restrained from defecating because of pain. The caput

coli is the seat of stoppage in the Rodentia.

Marsupials give such a high relative incidence that especial search of

their records was made, without, however, very definite result. In three

of the seven cases an acute general infection existed, in one an acute

peritonitis which seemed to emanate from a small ulcer in the ileum, in

one an injury to the anal region was found while in the remaining two

the notes would suggest that the lower intestine was atonic, judging by

its distention, translucency and pallor. In five the stoppage took place

in the large bowel alone, in the others both divisions being affected.

It is often difficult to establish a diagnosis of constipation in birds

because many varieties form a long rather dry mass in the lower small

intestine, to be moistened in the cloaca for discharge. Still again the

groups with capacious ceca are apt to have them filled normally with

firm casts. Diagnoses of fecal inspissation and stoppage in the smaller

tube have been made seldom, but one must consider also the obstruction

offered by excessive urate collections either in the cloaca or lower

ileum which will amount to a constipation if the cloaca be over-dilated

and dried urates mixed with dirt or feathers cover the anal opening.

The causes of this condition in birds are usually mechanical,

inflammation being found in a small minority of cases. In the small

passerine birds, seeds, sand, or parasites form the commonest findings.

This is also true of parrots, while excessive urate collections are

noted for both these groups. The gallinaceous birds present two reasons

for fecal stoppage—disease of the ceca (see pages 205–6) and cloacitis

probably secondary to anal closure by excessive urate collection. Uratic

stones, varying from one to five millimetres in diameter, have been

found in the cloaca in several orders. In only one case, a pheasant, did

they cause ulceration and cloacitis. Sand, rust, grains and the like are

found frequently, and sometimes in groups of birds, indicating that the

specimens had not been put upon the correct flooring or caging. Unbroken

seeds may obstruct the lumen.

MECHANICAL OBSTRUCTION.

Although the following is not constipation it is well to cite at this

place an experience which amounted to mechanical intestinal obstruction.

A number of finches were subjected to postmortem and found to have whole

white millet seeds in their intestines, this being the only discoverable

cause of death. Investigation revealed that during the night mice ate

the canary seed in the pans, leaving only the millet, which the hungry

birds consumed whole. Small birds can take a few millet and crack them

when eating leisurely, but apparently not when hungry. When the food was

removed at night the trouble ceased.

Obstruction by sand is well illustrated by a peculiar form of pica, in a

goose, which is worth citing, and calls to mind the sand disease of

horses:

Canada Goose ♂ (_Branta canadensis canadensis_).

DIAGNOSIS.—Masses of sand in entire intestinal tract. The general

condition externally and internally is good. The crop is distended

like a sausage, quite firm and the overfilling is obviously due to

sand in which very few stones, which could be called pebbles, are

found. This mass continues into the esophagus making the whole tract

impassable for food. The mucosa is a little pink and dirt-stained in

places but is not visibly inflamed. The gizzard is contracted over a

mass of sand but no food. Sand in more or less definitely packed

condition is found all along the gut tract, in one place in the small

coil it being quite as tight as in the crop and no lumen remaining.

Sand and bits of shale are found in ceca. The organs are apparently

healthy, slightly pale perhaps, but certainly not distinctly anemic.

No infection exists. The aorta, just above renals, has a 15 mm. × 2

mm. pale opacity of same consistency as the rest of the vessel, just

perceptibly higher than surrounding surface.

“Sand disease” has occurred in a Persian Wild Ass (_Equus onager_)

causing in this case ulceration, perforation and peritonitis, a Common

deer (_Mazama virginiana_) and a Chapman’s zebra (_Equus burchelli

chapmani_). The collection of sand is always greatest in the caput coli,

but may coat the large bowel to the anus.

Larger and more definitely obstructive physical objects are found in

both mammals and birds. We have on record a lion (_Felis leo_) and a

tiger (_Felis tigris_), which swallowed pieces of bone large enough to

be stuck in the small intestine and completely occlude it. Smaller

objects like buttons have been found even in the passerine tract. Worm

masses may occupy such a large part of the lumen of the tube as to

constitute a physical obstruction. This is definitely less important in

mammals than in birds, especially in the passerine order of the latter

class.

Dilatation of the intestine aside from that occurring in connection with

fermentation, constipation or ileus, in other words chronic atonic

dilatation, has not been encountered. Acute dilatation has been found in

several orders under the picture known for domesticated animals. Its

pathology and incidence have already been discussed.

ILEUS.

Ileus or acute intestinal obstruction may be divided for our purposes

into intussusception, volvulus, strangulation and paralysis from

interruption of mesenteric circulation. Examples of all these varieties

have been encountered and illustrative cases will be cited. In so far as

incidence is concerned, the Ungulata and Carnivora greatly outnumber all

other orders, showing seven cases each; the sum total in all other

orders is but eight. Upon re-reading some of the protocols I have,

however, excluded three invaginations in the carnivores, one each in the

ungulates and rodents, as probably being postmortem or shortly

antemortem occurrences; two had very early peritonitis but other things,

sufficient to account for death, were present. These deductions bring

the total cases of ileus in mammals to seventeen. Five cases in birds

will be discussed briefly.

Primates present one case of volvulus, one of intussusception and one of

internal strangulation. The first displayed the entrance of four inches

of ileum into the colon with such swelling of the wall as to prevent

reduction. The exciting cause seemed to be an enteritis, the cause of

death a peritonitis. A white-collared mangabey (_Cercocebus collaris_)

was the victim of volvulus probably favored by an anomalous position of

the transverse and descending colon which lay to the right, the latter

traversing the abdomen obliquely from right to left to reach the pelvis.

The volvulus occurred in the ileum just above the cecum, the twisted

part being found adherent by the peritonitis. The third case is a

strangulation due to peritonitis from filaria and adhesions between

stomach and colon from a colitis and pericolitis due to cestodes, one of

which was found deeply implanted in the colonic wall.

Two cases of intussusception are noted (after deductions above) for the

Carnivora. They both occurred in the ileum, one restricted thereto, the

other extending into the colon. In both a vague history of being “off

their feed” or giving evidence of intestinal trouble could be obtained

from the keeper. The three excluded cases had invaginations in the

middle and lower small intestines but not at the cecal valve. Volvulus

did not occur in the Carnivora.

A paradoxure (_Paradoxurus hermophroditus_) died as the result of a

strangulation of a six-inch knuckle of gut which had passed through a

hole in the omentum. The animal had not been eating well for a month but

gave no signs by which this ileus could have been diagnosed. Perhaps it

had existed for sometime but only shortly before death had swollen

sufficiently to cause obstruction.

Having excluded a doubtful invagination in a small rodent there remains

an interesting though somewhat obscure case in a porcupine (_Erethizon

dorsatus dorsatus_). This animal suffered with an acute hemorrhagic and

catarrhal enteritis while the colon seemed free of change until the

rectum was reached. Here was a stretch of a foot with the purple,

lusterless but translucent appearance of a strangulated intestine

although no involution or twisting remained. This was looked upon as a

volvulus which had untwisted a few hours before death.

Intussusception was seen only once in the Ungulata, a tapir (_Tapirus

terrestris_) with chronic enteritis. Here the ileum had passed into the

colon for a distance of nine inches, it being much swollen and congested

but not gangrenous. Its condition warranted the idea that the process

was antemortem but a peritonitis had not arisen, death having occurred

from the slight extra shock in an animal suffering with chronic

malnutrition. Volvulus was encountered three times, two deer and a

zebra. The last was the animal already described that carried such a

heavy load of sand in the gut tract, a factor in the production of the

twist probably although this might have been aided by a fibromyoma of

the colonic wall. The location of the volvulus in this order was twice

in the dilated descending colon, the third in the jejunal area. This

last was a twist which resembled an internal strangulation because of

the intricate knot-like windings of the small bowel.

The marsupials present two interesting cases. A rock kangaroo

(_Petrogale pencillata_) had chronic gastric ulcerations with local

peritoneal adhesions which apparently obstructed nearby coils of

intestine so that they became inflated and twisted over. An opossum had

a volvulus of the stomach which performed one and a half turns from left

to right; its protocol follows.

Common Opossum ♂ (_Didelphys virginiana_). Ileus. One and one-half

complete volvulus turns of stomach on duodenum. General condition

fairly good. Abdomen quite prominent, a condition found to be due to

great dilatation of the stomach which occupied the whole anterior part

of the abdominal cavity. The organ is blue and the vessels stand out.

Postmortem changes are occurring everywhere favored by the obstruction

to the circulation. The dilated stomach has undergone a volvulus upon

the third part of the duodenum making one and a half turns. The spleen

lies upon the right side well below the liver; it is swollen, soft and

deep purple. The duodenum in its upper half takes part in the

dilatation and beginning gangrene. The pedicle of the twist is made of

the duodenum, esophagus, edge of the mesentery and the middle part of

the pancreas; the end of the tail of the last is gangrenous. There is

no apparent obstruction lower down to explain the twist of the

stomach.

Among the Aves the following cases only are worthy of report. A parrot

(_Melopsittacus undulatus_) was found to have a tightly packed mass of

worms in the end of the duodenum above which the bowel was distended,

elongated, doubled on itself and of a deep red color; below this the

small intestine was empty. A closely similar condition was found in a

Screech Owl (_Otus asio asio_) the obstruction occurring just above the

end of the small gut. A Sparrow Hawk (_Falco sparverius_) had an

invagination two cm. in length, a short distance above the end of the

small intestine. No peritonitis existed but the presence of an acute

enteritis helps to explain the intussusception.

HERNIA.

Hernia is not a common occurrence among the lower animals but our

experience is instructive in two particulars, to wit, its absence in the

orders preceding the Rodentia and the frequency of the traumatic

variety. There being no general remarks to be made upon the subject, it

seems well to give a summary of the findings in each of the seven cases.

A Western Fox Squirrel (_Sciurus rufiventer_) showed a diaphragmatic

defect on the right side, a rounded opening with smooth edges, through

which a loop of intestine had passed, entering behind the liver and

reaching into the pleura as high as the pulmonary apex where it was

adherent; this was probably of long standing. Two more loops were found

wedged in the diaphragmatic hole, one of which was gangrenous.

An Indian Antelope (_Black Buck_) (_Antilope cervicapra_) presented an

irreducible incarcerated but not strangulated umbilical hernia. The

peritoneum was fused with the aponeurosis at the ring but the gut was

not adherent at this point while it was attached within the sac outside

the muscle, thus forming the incarceration. Apparently the sac had

dissected between the muscular layers for it could be followed for

several centimetres in some directions. A Hog Deer (_Cervus porcinus_)

had apparently suffered an injury in the flank for at one point the

muscles were irregularly cicatrized and a rent was present through which

several loops of intestine and a band of omentum had escaped, being

adherent to fascia. No injury to the skin was apparent.

Another Indian Antelope showed a clean traumatic rupture of the muscle

_and peritoneum_ in the right inguinal region _without_ penetration of

skin. An acute hernia had occurred which was lightly adherent to fascia

and an acute peritonitis was beginning. The bowel was however not

strangulated.

An aoudad (_Ovis tragelaphus_) seems to have suffered an injury by a

pointed object (horn?) just to the right of the ensiform cartilage for

at this position there is a circular hole, with smooth healed edges, in

the aponeurosis, permitting the emersion of a peritoneal sac containing

omentum. All parts were adherent but no acute inflammation existed.

What may have been a hernia or a relaxation of the transversus perinei

was observed in an Undulated Grass Parrakeet (_Melopsittacus

undulatus_). A bulge about the size of the finger end was seen

externally, beside and behind the anus. This proved to contain several

loops of bowel and a mass of fat.

A lateral abdominal hernia was seen in a Barbary Turtle Dove (_Turtur

risorius_). It consisted of a peritoneal sac and two loops of intestine.

This protrusion, while firmly fixed in its unnatural position, was in no

way constricted.

RECTAL PROLAPSE.

Prolapse of the rectum may in a sense be looked upon as a hernia or at

least as a relaxation of the anal and perineal muscles with protrusion

of parts normally situated intracorporeally. Although not frequent it

has been incurable in the animal, as it frequently is in man without

operation, a measure we have not adopted. Just what determines weakness

in the pelvic outlet is entirely obscure for indeed we have seen here

wounds and inflammations of the perineal area without prolapse of the

rectum and in none of the cases of prolapse did the pelvic floor seem

injured or diseased. It is but speculation to blame the annular muscles

of the anus. Tenesmus, or at least reasons for this straining action,

have been sought, with the result that in our cases lesions of the egg-

laying apparatus in birds and enteritis in mammals have stood out most

prominently. In no case have hemorrhoids been encountered nor has a

tumor pendant from the colonic mucosa, drawn the bowel toward the anal

opening. It might be added parenthetically here that hemorrhoids are

practically unknown for quadrupeds, Hutyra and Marek failing to mention

them independently and only one reference being found in the

_Jahresbericht fur Veterinär Medizin_ (Schmidt 1914–169); this case is

more like angioma than hemorrhoids. If tenesmus be active in the

production of rectal prolapse then it would have to be assumed that this

straining effort can be induced by enteritis since eversion of the

rectum has occurred with this disease in the absence of colitis, the

condition usually expected in the presence of tenesmus. The thirteen

cases have been seen in Mammalia, 8, (Carnivora, 2, Rodentia, 1,

Ungulata, 3, Edentata, 1, Marsupialia, 1) and Aves, 5, (Passeres,

Picariæ, Striges, Psittaci and Galli each one). Three mammals had

enteritis, one had foreign bodies in the bowel and one had many

ascarids; three had no demonstrable or suggestive causes. Two of the

five birds had enteritis high in the tract, one had uratic calculi in

the cloaca, and three had trouble in the egg-laying apparatus: one too

large an egg, one a broken egg and one a salpingitis.

DIVERTICULA.

It is almost certain that in a human pathological service of fifty-five

hundred autopsies, one or more diverticula of the Meckel variety would

be encountered and perhaps several of other kinds. In our material only

pouchings or false diverticula of the colonic wall are recorded, and our

personnel has often spoken of the absence of these gross abnormalities

of the alimentary tract. The two cases, notes of which are given, are

instances of hernial pouchings of the colonic mucosa and serosa, a

condition which is well known in human medicine. It may be said to occur

in two varieties, one in which the pouchings have heavy walls formed by

a thickened mucosa, muscularis and peritoneum and one in which the

bulgings have delicate walls, then being small herniæ of the inner coats

through rifts in the outer. Such a division is probably unnecessary or

misleading since the latter may be only a forerunner of the former.

However the clinical evidence of the simple variety is scanty and may be

little more than constipation while the peritonitic variety gives a

clinical picture of pain, constipation and a mass in the left abdominal

area, then known as diverticulitis or pericolitis sinistra. In these

cases the colon is much distorted by the irregularity of its mucosa and

by inflammatory thickening of the muscularis and serosa. Diverticula

arise from defects of the muscular coat, or secondarily after

inflammation or prolonged constipation, by weakness of muscle, or as

hernial protrusions around the entrance of blood vessels where the

muscle is thin. Such sacculations permit feces to collect and continue

the inflammation, thus further weakening the gut and producing

constipation, the whole vicious cycle being favorable to the formation

of more sacculations; coproliths may form in the diverticula. The two

monkeys now reported seem to have varying grades of the same condition,

a long standing colitis with diverticula, constipation and the

collection of inspissated feces in the sacculations. These animals did

not have hemorrhoids.

Black Ape ♀ (_Cynopithecus niger_). Coprostasis. Coproliths in

diverticulum. Chronic colitis. Cor bifida. The large intestine is of

the same calibre as the small intestine should be when not distended.

The sacculations as seen before opening the organ are salient, forming

distinct pouches. In one or two cases they are so pronounced as to

constitute diverticula 7 cm. long. In two instances the serosa at the

fundi of these diverticula is markedly hyperemic and very thin. In

many cases the sacculations contain coproliths. The wall of the organ

is distinctly thickened, puckered, inelastic and opaque. Mucosa is

thrown up into coarse rugæ.

Japanese Macaque ♂ (_Macacus fuscatus_). Chronic hypertrophic colitis.

False diverticula of colon. The large intestine contains a moderate

quantity of quite constipated feces. The serosa is smooth. The wall

shows at several stretches enlargements of the normal sacculations,

forming false diverticula. The wall of the gut in these herniæ is

thinner than in the surrounding parts; no ulcers exist; no local

peritonitis is present. The mucosa everywhere is irregular in

thickness, less translucent than normal and thrown into irregular

rugæ; tenacious mucus covers it. No ulcers.

TUMORS.

Only one tumor was observed in the mammalian intestinal tract proper.

Dasyure (_Dasyurus maculatus_) Adenocarcinoma of the intestines. On

postmortem there was a pale diffuse thickening of the coats of the small

gut over a large area; numerous soft, light yellow, sharply

circumscribed, elevated (like secondary tumors) nodules in the liver and

spleen, and a pea-size whitish nodule around a bronchus in the right

lung. Histological section of primary growth not made but a cross

section of the intestine in the vicinity shows an adenomatous change

with considerable increase in the connective tissue. The nodules in the

liver, spleen and lung and the appearances of the abdominal lymph nodes,

found microscopically, are precisely similar. They consist of

irregularly arranged epithelial nests and distorted acini, around which

are sharply outlined spaces, filled with the remains of degenerated

blood or a granular material. The metastases are always sharply

outlined.

Aves supply three papillomata which are interesting in that one occurred

in the proventricle, and two grew in the duodenum in the vicinity of the

upper biliary opening and presented within the lumen soft masses which,

while not occluding the passage, offered some little obstruction as

indicated by a slight distention above their location. In two, carefully

studied, no indications of parasites or of cancer could be found. The

birds concerned were an amazon, an owl, and a rhea.

SECTION VII

THE ALIMENTARY TRACT, PART 2. THE LIVER

A consideration of the liver is anatomically and physiologically the

next step in the discussion of diseases of the alimentary tract. While

this organ may participate in most of the pathological states of the

tubal part of the system, it is comparatively seldom the primary seat of

change and when damaged seems to be possessed of great accommodative and

reconstructive power. This must be true, and fortunately so, since we

ascribe to it the major detoxicating function of the body. Nevertheless

it is noteworthy that the largest solid organ of the animal body shows a

relatively low percentage of changes threatening to life. In the sense

of Pearl’s method of statistics, it does not “break down” easily. In

pathology it is the custom to list with great care all the changes,

gross and minute, in the liver, but with a few exceptions they are

secondary or incidental. They do however reflect many things, especially

referable to diet and to chronic infection from the intestinal drainage

area. It is in these directions that the organ will be studied in the

following pages.

Anatomically the liver is situated in the right upper part of the

abdomen subjacent to the diaphragm in both mammals and birds, being held

in position by attachment to this transverse partition, by ligaments or

folds of peritoneum, and by the other abdominal viscera. Its general

relationships do not offer great variations since in all animals means

are afforded for a dual blood supply and an outlet for the hepatic

secretion, the bile, into the higher intestines. Naturally variations in

the size of the lobes are observed and there has been considerable

speculation as to their independence and association. From the

standpoint of comparative pathology, little can be ascertained to assist

in this matter unless the position of abscesses and hepatitis relative

to cholecystitis have a bearing; some discussion of this will appear

later. We have not observed any peculiar pathology of the lobes of

Spigelius and Riedel. In so far as the size and arrangement of the organ

is concerned a few general facts of significance may be mentioned.

It was formerly thought that the liver varied inversely as the size of

the animal but Magnan[23] and others have shown that the matter is not

so simple. In the first place if there be an actual mathematical formula

it is that the liver varies in size inversely as the surface area of the

body, but this is not the whole story. It seems that the relation of

size of the organ to its weight is not constant and that it is better to

judge of the organic capacity by the latter. In herbivorous animals,

both birds and mammals, the liver is lightest per kilo of body weight;

next in weight are in order, fisheaters, meateaters, insectivora,

seedeaters, fruiteaters and omnivora. There is besides this a roughly

inverse ratio between the size of the liver and the length of the

intestine and in the class Aves inversely as the size of the lungs also.

From the immediately foregoing statements it is apparent that a

bewildering variation occurs and that only rough measurements of the

relative volume of the liver are available. An attempt was made in the

Marsupialia, which present all the variations given, to discover if any

peculiar pathology corresponded with the above groups; as it was

fruitless, no change from our zoological treatment will be made.

Lobar arrangement varies from the relatively simple double avian type to

the manifold lobulations of the seal or the marsupial but I can find no

literature to indicate that lobes or lobulations have a direct effect

upon functions. There must be a difference of blood supply for in

certain infectious diseases like enterohepatitis and amœbiasis, the

cystic and extreme right lobes are more affected than the left parts of

the organ. In the bird this is not so difficult to follow since the

three divisions of the portal vein, while they combine at times in an

ampulla within the hilum of the liver, seem directed to certain lobes,

that from the left portal seeming to point toward the right side. The

avian portal system differs from the mammalian in having a large branch

from the renal area, the so-called renal-portal system, pass to the

liver, and by having a free anastomosis between the portal area and the

caudal vena cava whereby blood from the pelvic district may pass into

the general circulation without going through the liver. There is no

unanimity of opinion as to the function or importance of this

connection[24] and from the data collected here there is no peculiar

renohepatic pathology.

The gall-bladder is not a constant organ in either mammals or birds and

indeed it may be absent or present in very closely related species (Two-

toed Sloth present, Three-toed Sloth absent). When present in mammals it

is usually a dependent bag while in birds it commonly lies upon the

cystohepatic duct, between the liver and the last curve of the duodenum,

in some varieties filling from the bottom, the inlet being guarded by a

valve. This cystic duct in nearly all birds, comes exclusively from the

right lobe while the hepatic duct, with which the cystic has no

connection, is formed by combination within the liver of radicles from

both sides. It passes to the duodenum well in advance of the cystic

duct, in some birds, _e.g._, the Struthiones, very near the pylorus,

that is on the descending limb of the duodenal loop. By this means

obstruction to the biliary stream is rendered difficult. The common duct

combines with one of the pancreatic outlets in most mammals but the

abdominal salivary gland in lower animals has more often patent separate

ducts or multiple ducts than it does in man. Birds have one to four

pancreatic ducts separate from the biliary openings.

The gall-bladder is missing in most varieties of the following groups:

pigeons, parrots, wrens, ostriches, rheas, cuckoos, toucans among the

birds; most odd-toed ungulates, hyraces, Indian elephants, all deer,

peccaries, three-toed sloth, and many rodents. The varieties lacking

this reservoir are herbivorous in the main, true carnivores seeming

always to be possessed of such a structure. Among the important

herbivorous ungulates, Bovidæ, Tragulidæ, Camelidæ and Suidæ have this

bile reservoir almost without exception. Because of the interest now

being shown in the pathology of the gall-bladder and its passages and of

the pancreas, it was hoped that evidence of definite practical value for

human pathology would be at hand in our study if we divided the animals

into groups with and without a bile reservoir. The result is not

unequivocal but worthy of note; it is discussed on pages 238 and 255.

Microscopically the well known lobular arrangement of the liver is

rather faithfully carried out among the mammals albeit the most

systematic and complete architecture is to be found in the pig while the

marsupial seems the most disorderly, thus resembling the avian organ. In

the latter class all the parts are indistinct, the cells having an

unclear outline, the tubules being intricately wound and the

interlobular connective tissue being scanty and not anastomosing in a

definite framework. The intralobular reticulum is especially difficult

to detect. Groups of cells are often found at portal spaces; these are

large and small mononuclears and granular cells, probably of the

hematopoietic system. It is possible that blood formation is performed

in the liver and spleen in some adult birds but such a function is

denied for the mammal except under very unusual conditions of bone

marrow atrophy.

Glycogenic and fatty conservation is a function possessed by both

zoological classes as are the detoxicating and bile-producing powers.

However it is highly probable that urea and creatin in metabolism is not

cared for by the avian liver as it is by the mammalian, judging by the

researches of Paton and of Richet.

FAT DEPOSITS.

The care of fat by the liver is very well shown by examining the

incidence of fatty metamorphoses through the various orders. In the

first place Mammalia show a slightly higher percentage of fatty change

than do Aves and should show a greater difference were it not for the

large number of cases in two orders of the latter. Among mammals,

lemurs, rodents and marsupials store fat in the liver more than other

orders but in the second and third, it is chiefly the carnivorous

varieties that have this property. Just why the slothful herbivorous

lemurs should be first on the list is not evident especially since the

grain-eating Ungulata are least apt to present fatty livers. With this

exception, mammals with plentifully available hydrocarbons in their diet

are most apt to show its deposit in the organ under discussion. Among

the birds the gallinaceous varieties stand far ahead of all others, the

passerines following next. Galli show the condition in association with

acute infections, chronic diseases and in health. Unless there be

distinct reason for it at autopsy, it may almost always be said to be

normal. Passeres, especially the smaller forms, frequently come to

autopsy with such excessively large livers, and indeed with a very large

pad of abdominal fat, and nothing else, that one is compelled to look

upon this overburdened organ as incapacitated by the deposit. These two

orders increase the percentage value for the birds. Striges, Anseres,

and Accipitres also show a good number of cases but there is among the

Aves no such clear relationship between food fat and fat infiltration as

may be found in the Mammalia.

AMYLOID DEPOSITS.

Amyloid deposit is reported with reasonable frequency in domesticated

animals, causing in them a fairly definite entity, being as usual

related to the effects of long continued or repeated infectious disease.

Wild animals suffer from this condition but rarely and therefore to our

few cases will be given a short discussion separately. An Indian

Paradoxure (_Paradoxurus niger_) had patches of amyloid irregularly

distributed through the organ. The animal had a carcinoma of the head of

the pancreas, an obstructive biliary cirrhosis in a state of atrophy and

a chronic nephritis with arteriosclerosis. There was nothing peculiar

about the distribution of the deposit as there was in the next case, a

Badger (_Meles meles_) where amyloid was found around the interlobular

vessels and extending in the lobules along their canaliculi. This latter

case seemed without cause and we have considered it a primary

amyloidosis, the spleen, heart muscle, kidneys, intestines and other

structures being affected. (See Fig. 7.) A third mammalian case

concerned a Dasyure (_Dasyurus viverrinus_) which showed distinct

intralobular collections. Its cause was a chronic suppurative process in

the jaw bone.

Avian livers are somewhat more prone to show amyloid deposits, eight

cases being on record. Four occurred in the Passeres, one each in

Columbæ and Impennes and two in Anseres. Three were associated with

chronic infectious disease and two with well established nematode

parasitism. The remaining three, classed as primary, were not related to

any other lesions, in two the amyloid liver being the only finding.

The next abnormal deposition related to the physiology of the organ is

blood pigmentation. Normally hemic pigment is dispensed with very

rapidly but under unnatural conditions it accumulates. In only one order

is there any noteworthy percentage of hemosiderosis, the carnivores, the

remainder showing a very trifling incidence.

DEGENERATIONS.

Going further into the physicochemical alterations of the liver brings

us to consideration of those changes known as degenerations—

parenchymatous, fatty, hydropic, hyaline, all of which we shall group

under one heading. They occur in a great variety of conditions and do

not appear to be specific, nor as the records are analyzed do they

appear to occur preëminently in any one disease of the lower animals.

The percentages are however higher for orders and families whose diet

contains relatively more protein, carnivores, the higher marsupials,

accipitrine, and wading birds.

ACUTE ATROPHY.

A very important degenerative disease of the liver is acute yellow

atrophy or, better expressed, acute degenerative atrophy for it is a

total destruction of the whole or large parts of the parenchyma. It is

apparently toxic in origin being related to the toxemias of pregnancy,

to certain organic and inorganic soluble poisons; some cases arise

without discoverable cause. We have seen no cases in the mammal but two

in birds. Both were females, one in active ovulation, while the other

had no related pathology and the condition of the ovaries could not be

determined since they had been destroyed after death by rats. The

macroscopic and minute anatomy offers nothing new. Jaundice was present

but not intense.

HEPATITIS.

True inflammatory lesions are to be defined as some form of

parenchymatous change to which are added congestion, infiltration of

round or polynuclear cells, stagnation in the bile ducts or perhaps

actual degeneration of their lining cells. It seems necessary to

stipulate these things because in the chronic forms, usually called

cirrhosis, it is necessary to have all of them, plus efforts at

regeneration, in order to determine it as a chronic progressive process.

Acute hepatitis is a rare condition in mammals except when it is

combined with septicemia or severe enteritis. In birds on the other hand

the liver is, aside from the intestinal wall, perhaps the most frequent

seat of pathology in the abdomen. This is because of its almost constant

involvement in infective enteritis, and in such conditions as fowl

cholera, fowl typhoid, coccidiosis and cecal amœbiasis, all of which we

have sporadically. When one searches for special distribution among the

orders, only one of them stands out as having a high percentage, the

Galli, an order which seems to have a very vulnerable liver.

The macroscopic anatomy of hepatitis in birds is peculiar in showing a

definite swelling with spots of gray or yellow color, sometimes

coalescing to form irregular areas. These are much more definite than in

the mammalian organ where swelling and hemorrhage are the commoner

findings. These pale spots are of two origins. They may be focal

necroses of the hepatic cells, with or without circumferential

congestion or hemorrhage to make them stand out. In amœbic, coccidial

and typhoid livers such is the type of change. In septicemia and

cholera, the mottlings are made up of increased interstitial mononuclear

areas, with blood cells and shadow cells numerously present. I have seen

what was in all probability a stage of repair after both these kinds of

change. In the former, regeneration seemed to take place from adjoining

liver cells, there being in the section no evidence of increased bile

ducts to make new hepatic cells. It seemed also that phagocytes were

derived from blood cells and not from Kupffer’s cells. In the

infiltrative lesion disappearance of the liver cells from the groups

leaving compressed and deeply granular remnants was all that could be

determined. Regeneration seemed to be progressing in the manner just

outlined.

NECROSES.

The degenerative and infiltrative areas of acute hepatitis are simulated

by focal necroses in livers not the seat of a general hepatitis from

which they can be differentiated only by the microscope. These small

areas of local tissue death are quite common in all pathological

processes but are most common in the liver, possibly because of its

exposure to toxins from the intestine. Their exact origin is not

determined, various explanations being given. The somewhat distinct

distribution in mammals _versus_ that in birds may help in the final

decision. In the former, focal necroses are more often encountered

midway in the anatomic lobule and around the central vein whereas a

perivascular location seems the usual position in the bird.

Massive necroses of the liver may be of considerable importance in

veterinary medicine. They take their origin in several different ways.

The commonest in our records are those due to cecal coccidiosis and

amœbiasis (quail disease and blackhead) while from the primary seat of

these two infectious diseases, the cecum, may originate the virus of

nonspecific hepatic necroses. We have observed several birds, passerine,

psittacine and gallinaceous, which at autopsy showed a distention of the

cloaca, ceca, and lower small intestine with urates and slime but no

mural inflammation and a large area of necrosis in the liver. This

suggests perhaps a “white diarrhœa” but it did not occur in epizoötics

and other morbid anatomy of this specific disease was absent. These

frequent instances of association between the colonic area and the liver

seem to suggest the transfer of necrotizing organisms, just as amœbæ

travel, and to indicate measures to clean out the tract when birds

become “plastered.” Massive necroses also arise from mould disease, and

from infection with the necrosis bacillus, emanating from nearby

infectious foci, or _via_ the normal passageways from the intestine.

Massive areas of degeneration may form by the coalescing of numerous

foci, in any septicemic disease.

ABSCESS.

In man, amœbæ, flukes, cestodes and biliary tract infection are the

commonest causes of purulent collections within the liver. In the lower

mammals parasites play practically a solitary rôle at least as the major

influence in localizing the collection, bacteria from the intestine

doing the rest. We have one case of massive abscess in a porcupine

suffering with septic pneumonia, the suppuration in the liver being due

to the colon bacillus, the general septicemia probably being from

distemper. Monkeys have shown more abscesses than any other order, three

being observed. One was due to infestation with trichocephalus which had

apparently penetrated from the colonic wall into the liver through

adhesions formed between these two structures. Another seems certainly

amœbic but these protozoa could not be found, while the third followed

an ulcerative enterocolitis of unknown cause. Two cats were seen with

parasitic abscesses; one harbored _Distoma_ or _Clonorchis sinensis_,

the other a nematode of ascaris type.

The topographic distribution of these six hepatic abscesses was

interesting. The position of the abscess is not mentioned in one case

but of the remaining five three were entirely in the right lobe, one had

the major lesion on the right side and smaller separate abscesses spread

over the organ, and one with about equal distribution in all lobes. All

three confined to the right side were solitary.

Abscesses of considerable size are not met with in the bird as in the

mammal perhaps because the former does not form real pus, necroses

developing instead.

Congestion of the liver is a matter of small importance from the

standpoint of pathology unless it be of sufficient duration to cause

cyanotic atrophy and induration. However the facts that congestion of

this organ occurs three times as often in the mammal as in the bird and

that vascular cirrhosis has not been seen in the latter class, are

interesting and noteworthy. In addition ascites of hepatic origin has

not been seen in the birds. The explanation for this lies in the rich

anastomosis between the intestinal area and the caudal vena cava so that

the blood does not have to pass through the liver to reach the heart.

This arrangement would reduce the back pressure in passive congestion

and relieve the liver in the congestion due to toxic or inflammatory

distention of small vessels.

CIRRHOSIS.

The chronic inflammations or so-called cirrhoses of the liver have been

subjected to a great deal of study and many theories have been expounded

as to their cause and classification. Here is not the place to discuss

the academic question of nomenclature but rather to adopt an acceptable

working classification and to analyze our material thereon. A cirrhosis

is a chronic inflammation of the liver indicated by increased connective

tissue with evidences of degeneration and attempts at regeneration on

the part of the hepatic cells. Certain cases of increased connective

framework fail to show the last two features and, since they must be

grouped near the cirrhoses because of the prominence of connective

tissue, they are called _fibroses_, _perilobular in type_. Among the

instances carrying out the full stipulations are livers with evidence of

a perivascular fibrosis and obstruction, to which are added degeneration

and regeneration of the lobular margins; such are PORTAL CIRRHOSES in

human medicine associated with passive congestion in the intestinal

area, and ascites. In a second variety, fibrosis seems to succeed upon

obstruction to the biliary lumina or upon peribiliary inflammation,

BILIARY CIRRHOSES. The effects of this are to dam back bile with the

production of varying degrees of jaundice and for the inflammation to

spread into the lobules, thus distorting their internal architecture;

this form is therefore unlike portal cirrhosis which alters the size and

shape of lobules as a whole. Fatty change is very prominent in certain

cases and it has been a custom, perhaps without warrant, to put such

livers into a separate group. It may be that they represent a different

chemical process. When there exists for a long time a venous stasis in

the liver, necrosis is apt to occur in the cells subjected to pressure

and the absence of fresh blood. This gives rise to a “nutmeg” liver upon

which may succeed a definite perivenous fibrosis.

This then is a working classification of the hepatic cirrhoses. Perhaps

many slightly differing varieties might be constructed but this grouping

will permit comparison and contrast with human cases, and with instances

in the various orders. Because of the relatively small total, thirty-

two, it is perhaps unwise to attempt any conclusions as to distribution

but it is certainly noteworthy that twenty-six occurred in mammals. This

means 1.6 per cent. in mammalian autopsies against .2 per cent. in

avian. Among the former class the carnivores stand at the head of the

list, followed in order by the marsupials, ungulates, primates, and

rodents.

Carnivora have shown a few typical portal cirrhoses from a pathological

standpoint but only one, in a badger (_Taxidea taxus_), was combined

with the classical picture of intestinal hyperemia and ascites. Two of

the cases were combined with chronic enteritis which may, of course,

have been secondary but there was also a hyperplasia of the spleen which

bespoke some grade of infection. None of the four showed involvement of

the biliary tract. One animal, a skunk (_Mephitis mesomelas_), was

jaundiced; it had anemia, nephritis and enlarged spleen but no

intestinal inflammation; perhaps the associated anemia may have been

responsible for the pigmentation. Biliary cirrhosis occurred in two

Carnivora, in both associated with enlarged spleen and nephritis. One

showed jaundice and the other, with a huge liver from congestion and

interstitial infiltration, had a small ascites. Fatty cirrhosis was

diagnosed in a raccoon but this is viewed with some reservation because

this animal easily stores fat and in this case it may not have been a

part of the process. In none of the foregoing cases did parasitism enter

into the causation of the change and I shall always specify when such a

factor was probable. The only vascular cirrhosis in our records occurred

in a Gray Wolf incident to a longstanding myocarditis (Gray Wolf, _Canis

lupus mexicanus_, Myocarditis, Adenomatoid goitre, Chronic

gastroenteritis, Vascular cirrhosis of liver, Subacute diffuse

nephritis, Edema of lungs, pericardium, and peritoneum). Two examples of

perilobular fibrosis appeared in this order, a raccoon (_Procyon lotor_)

and a paradoxure (_Trichosurus vulpecular vulpecular_). The only

noteworthy feature was, in the former, a very marked biliary stasis on

the lobular margins and in the connective tissue; this animal was not

jaundiced.

Ungulata are normally well supplied with definite interlobular strands

which, in a few varieties, completely encircle the lobule but always

show as clear fibrous septa going out from the portal areas. This

richness of connective tissue renders more difficult a decision of

increase so that unequivocal degenerations and regenerations with

inflammatory changes have been demanded as criteria for cirrhosis. It

has been recognized that cattle get a definite increase in their

interstitial tissue without serious reaction in the parenchyma. With the

knowledge of these facts in mind it has been possible to detect two

distinct portal cirrhoses, two biliary cirrhoses and three perilobular

fibroses. It is however evident by examining the rest of the autopsy

notes that the chronic inflammations have had with one exception, little

influence on the animal’s life and death and the associated pathology is

not instructive in etiology. One old deer with the definite portal type

had ascites and intestinal hyperemia which hastened his end.

The type of cirrhosis in the marsupial is progressively inflammatory and

of the biliary variety. In two of the three cases there was active

infection somewhere in the body, one a long continued streptothricosis,

the other and more important a choledochitis with involvement of the

pancreatic head. The third case showed a nephritis and a

pericholedochitis and pericholecystitis. In all three there was definite

evidence of biliary obstruction within the liver and in the occurrence

of general jaundice.

Monkeys have presented one portal, two biliary, and one perilobular

cirrhoses. The London Garden reports a cirrhosis with gall stones in a

Chimpanzee. The case of the Barbary Ape is so good that it is quoted in

brief.

Barbary Ape ♀ (_Macacus innuus_). Found dead. Never known to be sick.

On exhibition nine years. Acute dilatation of stomach. Acute

gastritis. Portal cirrhosis of liver. Acute parenchymatous nephritis.

Chronic passive congestion of lungs. Chronic splenitis and

perisplenitis. Ascites. Mild passive congestion of abdominal

circulation. On opening the abdomen a dilated stomach occupies most of

the anterior part, displacing the intestines downward and backward.

The upper lobes of both lungs are uniformly deep red, soft, collapsed,

subcrepitant. Subclavian vessels—veins distended with red clot,

arteries with small amount of chicken fat clot. The heart is dilated

on the right side, filled with currant jelly clot. The liver is small,

surface hobnailed, edges rough, consistency tough, color brown.

Section surface glistening, moist, granular and opaque, mottled by

irregular brown areas separated by paler brown intercommunicating

bands. Gall-bladder is small, contains viscid yellow bile and duct is

patulous. Areolar tissue about the bile ducts is thick and opaque, the

duct wall itself is thick and yellow. Gall-bladder tightly attached to

capsule of liver. Spleen is slightly enlarged, soft and tough. Capsule

is smooth, opaque and thickened on gastric surface. The trabeculæ are

prominent, pulp mottled gray-red, few recent hemorrhages. Capsule of

the kidneys is smooth, strips easily leaving a smooth brown surface

with dilated vessels. Organ is soft. Section surface is glistening,

striæ wide and indistinct, glomeruli faintly visible. Microscopic

section of liver shows high grade of fibrosis almost entirely confined

to portal areas with a marked increase in bile ducts although no place

is found where these bile ducts are running into lobules suggesting

attempt at regeneration. Liver cells show high grade of fatty

degeneration in some places, whole lobules being necrotic. There is no

pigmentation and connective tissue is fairly rich in cells. Fibrosis

quite well advanced. Cells about equally fibroblasts, round cells and

polynuclears. Bile ducts very well preserved and cellular infiltrate

rather less directly around them than at other parts of connective

tissue. The section of kidney shows moderate congestion, granular and

vacuolar degeneration of epithelium generally distributed except in

proximal tubules where there is swelling and desquamation. Detritus

present in tubules and capsular spaces. Tufts swollen.

The biliary forms of Primates were associated in one case with an

undetermined parasite in the bile channels, in the other with

tuberculosis and chronic enteritis. In all the cases the relative

inconspicuousness of bile in ducts or in cells is worthy of mention. The

perilobular fibrosis in a small cebus was trifling in extent but was

associated with considerable round cell infiltration in isolated areas;

there was also nephritis, splenitis, and enteritis.

The only representative of the rodents is a capybara (_Hydrochœrus

hydrochœrus_), their largest variety. This case was originally described

as a typical Lænnec or Pictou cirrhosis but I now class it as a portal

form. The distinct insular arrangement of the lobules, the failure of

involvement of the bile channels and the ascites are reasons for the

present decision. The animal suffered also from tuberculosis (not in

liver) and myocarditis.

The Indian Elephant, “Bolivar” (_Elephas indicus_), an old specimen, is

the only member of his order to show cirrhosis. It may be considered as

a senile process in part but the extreme distortion and compression of

the lobules press the conclusion that it was a progressive inflammation.

[Illustration:

FIG. 18.—PORTAL CIRRHOSIS OF LIVER IN ATROPHIC STAGE. BARBARY APE

(MACACUS INNUUS). THE DILATATION OF THE STOMACH ALSO SHOWS IN

PHOTOGRAPH.

]

[Illustration:

FIG. 19.—ATROPHIC PORTAL CIRRHOSIS OF LIVER. INDIAN ELEPHANT (ELEPHAS

INDICUS).

]

Aves fail to show lesions which could be called portal cirrhosis, five

of their six cases being biliary and one fatty with signs of continued

infection. The macroscopic anatomy of the avian liver with chronic