which occurs in the course of the disease, for during the intervening
period or coma there is no means of determining that it is due to this
complication. Severe cases of influenza may simulate anthrax in the
horse. In both we have stupor, the intense coloration of the mucous
membranes of the eyes, and a certain amount of swelling of the legs and
under surface of the belly. The diagnosis here can be made only by
microscopic examination of the blood. In strangles, equine variola, and
scalma we have an intensely red, rosy coloration of the mucous
membranes, full, tense pulse, and although in these diseases we may have
depression, we do not have the stupor and coma except in severe cases
which have lasted for several days. In influenza we have no evidence of
the formation of pus on the mucous membranes as in the other diseases,
except sometimes in the conjunctivae.
In severe pneumonia (lung fever) we may find profound coma,
dark-yellowish coloration of the mucous membranes, and swelling of the
under surface of the belly and legs; but in pneumonia we have the
history of the difficulty of breathing and an acute fever of a sthenic
type from the outset, and the other symptoms do not occur for several
days, while in influenza we have the history of characteristic symptoms
for several days before the rapid breathing and difficulty of
respiration indicate the appearance of the complication. Without the
history it is frequently difficult to diagnose a case of influenza of
several days' standing, complicated by pneumonia, from a case of severe
pneumonia of five or six days' standing, but from a prognostic point of
view it is immaterial, as the treatment of both are identical. The fact
that other horses in the same stable or neighborhood have influenza may
aid in the diagnosis.
_Prognosis._--Influenza is a serious disease chiefly on account of its
numerous complications. Uncomplicated influenza is a comparatively
simple malady, and is fatal in but 1 to 5 per cent of all cases. In some
outbreaks, however, complications of one kind or another preponderate;
in such instances the rate of mortality is much increased.
_Alterations._--The chief alteration of influenza occurs in the
digestive tract, and consists in hyperemia, infiltration, and swelling
of the mucous membrane, and especially of the Peyer's patches near the
ileocecal valve. The tissues throughout the body are found stained, and
of a more or less yellowish hue. There is always found a congested
condition of all the organs, muscles, and interstitial tissues of the
body. The coverings of the brain and spinal cord partake in the
congested and discolored condition of the rest of the tissues.
Other alterations are dependent entirely upon the complications. If the
lungs have been affected, we find effusions identical in their intimate
nature with those of simple pneumonia, but they differ somewhat in their
general appearance in not being so circumscribed in their area of
invasion. The alterations of meningitis and laminitis are identical with
those of sporadic cases of founder and inflammation of the brain.
_Treatment._--While the appetite remains the patient should have a
moderate quantity of sound hay, good oats, and bran; or even a little
fresh clover, if obtainable, can be given in small quantities. It is not
so important that a special diet shall be observed as that the horse
shall eat a moderate quantity of nourishing feed, and he may be tempted
with any feed of good quality that he relishes. He should be placed in a
well-ventilated box stall away from other horses. Grass, roots, apples,
and milk may be offered and, if relished, allowed freely. To reduce the
temperature the safest simple plan is to inject large quantities of cold
water into the rectum. Antipyrene may be used with alcohol or strychnia.
Derivatives in the form of essential oils and mustard poultices, baths
of alcohol, turpentine, and hot water, after which the animal must be
immediately dried and blanketed, serve to waken the animal from the
stupor and relieve the congestion of the internal organs. This treatment
is especially indicated when complication by congestion of the lungs,
intestines, or of the brain is threatened. Quinin and salicylic acid in
1-dram doses will lower the temperature, but too continuous use of the
former in some cases increases the depression. Iodid of potash reduces
the excessive nutrition of the congested organs and thereby reduces the
temperature; again, this drug in moderate quantities is a stimulant to
the digestive tract and acts as a diuretic, causing the elimination of
waste matter by the kidneys. Small doses of Glauber's salt and
bicarbonate of soda, used from the outset, stimulate the digestive tract
and prevent constipation and its evil results.
In cases of severe depression and weakness of the heart digitalis can be
used with advantage. At the end of the fever, and when convalescence is
established, alcohol in one-half pint doses and good ale in 1-pint doses
may be given as stimulants. To these may be added 1-dram doses of
turpentine.
In complications of the intestines camphor and asafetida are most
frequently used to relieve the pain causing the colics; diarrhea is also
relieved by the use of bicarbonate of soda, nitrate of potash, and
drinks made from boiled rice or starch, to which may be added small
doses of laudanum.
In complication of the lungs iodid of potash and digitalis are most
frequently indicated, in addition to the remedies used for the disease
itself.
Founder occurring as a complication of influenza is difficult to treat.
It is, unfortunately, frequently not recognized until inflammatory
changes have gone on for several days. If recognized at once, local
bleeding and the use of hot or cold water, as the condition of the
animal may permit, are most useful, but in the majority of cases the
stupefied animal is unable to be moved satisfactorily or to have one
foot lifted for local treatment; the only treatment consists in local
bleeding above the coronary bands and the application of poultices.
During convalescence small doses of alkalines may be kept up for a short
time, but the greatest care must be used, while furnishing the animal
with plenty of nutritious, easily digestible feed, not to over-load the
intestinal tract, causing constipation and consequent diarrhea. Special
care must be taken for several weeks not to expose the animal to cold.
_Prevention._--In order to prevent the introduction of the disease it is
advisable to isolate newly purchased animals for at least a week.
Further, the stabling of healthy horses in sales and feed stables should
also be guarded against. At the beginning of an outbreak the disease may
be checked by immediate isolation of the affected horses, by taking the
temperatures of the healthy animals, and by the segregation of those
showing a marked elevation.
Bacterial vaccines are now being prepared for the prevention of this
disease and also for its cure, but to date the results are not
convincing as to the beneficial action of these products. Since the
cause of the disease has not yet been satisfactorily determined it is
difficult to conceive how immunity could be produced with the aid of the
germs which enter into the preparation of these products. The reports
would indicate, however, that vaccines exert a favorable influence upon
the course of the disease, probably preventing severe complications
which under ordinary conditions are the principal factors in determining
the severity of the outbreak.
CONTAGIOUS PNEUMONIA.
_Synonyms._--Edematous pneumonia; stable pneumonia; equine
pleuropneumonia; influenza pectoralis equorum; pleuropneumonia;
influenzal pneumonia; Brustseuche (German).
Contagious pleuropneumonia is an acute contagious disease of horses
manifesting itself either as a croupous pneumonia or a pleuropneumonia
with complications in the form of serous infiltrations of the
subcutaneous tissues and tendons.
_Etiology._--Investigators of this disease incriminated various kinds of
microorganisms as the cause of this affection. Transmission experiments
were usually negative with these organisms. This was also the case in
attempts to transmit the disease by feeding with affected parts of the
lungs, intestinal contents, and nasal discharge; likewise by
intravenous or subcutaneous injections of blood and of emulsions made
from nasal discharge, urine, the lung, and other organs.
The most recent experimental results of Gaffky and Lueber proved that at
least at the beginning of the disease the bronchial secretion contains
the infection. Upon killing horses affected with the typical forms of
the disease on the third or fourth day of the affection the air passages
are usually found to be filled with a yellowish, tenacious, germ-free
secretion with which they succeeded in infecting healthy colts. The
virus has not been isolated. The possibility of its being a protozoan is
suggested by the above-named investigators through their observations of
round or rod-shaped bodies in the round cells of the secretions.
Two organisms were formerly especially considered to play an important
part in the cause of the disease, the _Streptococcus pyogenes equi_,
which has been isolated from most cases of the disease, and the
_Bacillus equisepticus_, which by some investigators was considered to
be the cause of contagious pleuropneumonia. Although there is no doubt
as to the presence of these microorganisms in most of the cases, their
association with the cause of this disease, however, is now doubted,
especially since attempts to transmit the disease with pure cultures of
these germs failed to reproduce the typical form of the disease. They,
however, are of great significance in connection with the pathological
changes occurring in connection with the infection and probably are the
determining factor in the course of the disease. They exert their action
after the animal has already been attacked by the true virus, and then
produce the inflammatory changes attributed to these secondary invaders.
This disease is the adynamic pneumonia of the older veterinarians, who
did not recognize any essential difference in its nature from an
ordinary inflammation of the lungs, except in the profound sedation of
the force of the animal affected with it, which is a prominent symptom
from the outset of the disease. Again, this same prostration of the
vital force of the animal, combined with the staggering movement and
want of coordination of the muscles, caused it for a long time to be
confounded with influenza, with which at certain periods it certainly
has a strong analogy of symptoms, but from which, as from sporadic
pneumonia, it can be separated very readily if the case can be followed
throughout its whole course.
Infectious pneumonia is a specific inflammation of the lungs,
accompanied with interstitial edema and inflammation of the tissues of
these organs and a constitutional disturbance and fever. It causes a
profound sedation of the nervous system, which may be so great as to
cause death. It is sometimes attended with pleurisy, inflammation of the
heart or septic complications, which also prove fatal.
Old, cold, damp, foul, unclean, and badly drained and ventilated stables
allow rapid dissemination of the disease to other horses in the same
stable and act as rich reservoirs for preserving the contagion, which
may be retained for over a year.
The virus is but moderately volatile, and in a stable seems rather to
follow the lines of the walls and irregular courses than the direct
currents of air and the tracts of ventilation. Prof. Dieckerhoff found
that the contagion of influenza was readily diffusible throughout an
entire stable and through any opening to other buildings, but he also
found that the contagion of infectious pneumonia is not transmissible at
any great distance, nor is it very diffusible in the atmosphere. A brick
wall 8 feet in height served, in one instance, to prevent the infection
of other animals placed on the opposite side from a horse ill with the
disease, while others placed on the same side and separated from the
focus of contagion only by open bars in the stall were infected and
developed the disease in its typical form.
_Symptoms._--The symptoms differ slightly from those of a frank,
fibrinous pneumonia, but not so much by the introduction of new symptoms
as by the want of or absence of the distinct evidences of local lesions
which are found in the latter disease. All the pneumonias throughout the
whole course of the trouble are less marked and less clearly defined.
The symptoms may develop slowly or rapidly. If slowly, there is fever
and the animal gives a rare cough which resembles that of a heavy horse
affected with a slight chronic bronchitis; it becomes somewhat dejected
and dull, at times somnolent, and has a diminished appetite. This
condition lasts for several days, or the disease may begin with high
fever, and the symptoms described below are severe and develop in rapid
sequence. The respiration increases to 24, 30, or 36 to the minute, and
a small, running, soft pulse attains a rhythm of 50, 70, or even more
beats in the sixty seconds. The heart, however, contrary to the
debilitated condition of the pulse, is found beating violently and
tumultuously, as it does in anthrax and septic intoxication. The mucous
membranes of the eyes and mouth and of the genital organs are found
somewhat edematous, and they rapidly assume a dirty, saffron color, at
times approaching an ocher, but distinguishable from the similar
coloration in influenza by the want of the luster belonging to the
latter and by the muddy, dull tint, which is characteristic throughout
the disease.
Suddenly, without the preliminary rales which precede grave lesions of
the lungs in other diseases, the blowing murmur of pneumonia is heard
over a variable area of the chest, usually, however, much more
distinctly over the trachea at the base of the neck and directly behind
the shoulder on each side of the chest. In some cases the evidence of
lung lesion can be detected only over the trachea. The lesions of the
lungs may be scattered throughout both lungs, involving numerous small
areas, or they may be confined to and more or less fully occupy one or
two lobes. Occasionally there is a general involvement of both lungs.
The body temperature has now reached 104 deg. or 105 deg. F., or in extreme
cases even a degree higher. The debility of the animal is great without
the stupefaction or evidence of cerebral trouble, which is constant with
such grave constitutional phenomena in influenza or severe pneumonia.
The animal is subject to occasional chills, and staggers in its gait.
The yellow coloration of the visible mucous membrane is rendered pale by
infiltration of the liquid of the blood into the tissues; the pulse may
become so soft as to be almost imperceptible, the heart movement and
sounds being at the same time exaggerated. The animal loses flesh
rapidly, and dropsies of the extremities, of the under surface of the
belly, or of the internal organs may show themselves.
_Terminations._--These symptoms may gradually subside after five to
eight days, with an improved appetite the inanition may cease and the
animal commence to nourish its impoverished blood and tissues; the pulse
becomes stronger and the heart more regular and less tumultuous; the
mucous membranes assume a brighter and more distinct color; the
difficulty of respiration is removed, and the animal may make a
recovery. When death occurs it is usually directly due to heart failure;
in some cases it is caused by asphyxia, owing to the great amount of
exudation into the lung tissue, rendering its further function
impossible.
_Complications._--The pulmonary complications of infectious pneumonia
are secondary inflammatory or necrotic changes in the lungs themselves.
Suppuration at times takes place in the bronchi and may extend to the
lung tissue. In this case mucous rales develop which are most distinctly
heard over the trachea and on the sides of the chest directly behind the
shoulders. With the development of the mucous rales, to be heard on
auscultation, we have a more purulent discharge from the nostrils,
similar to that of a chronic or subacute bronchitis. If the inflammation
has been of some standing, cavernous rales may be heard, indicating the
destruction of a considerable portion of lung tissue and the formation
of a cavity. The effects of this more acute inflammatory process are not
appreciable in the general condition of the animal, except to weaken it
still further and add to its debilitated and emaciated cachexia.
Gangrene sometimes occurs. A sudden rise of the body temperature of 1 deg.
or 2 deg., with a more enfeebled pulse and a still more tumultous heart,
develop simultaneously with the appearance of a discharge from the
nostrils. This discharge is gray in color, serous or watery in
consistency, mixed with the detritus of broken-down lung tissue, and
sometimes contains clots of blood, or in more serious cases may be
marked by a quantity of fluid blood from a hemorrhage, which proves
fatal. The discharge is fetid to the smell. The animal emaciates
rapidly. On examination of the lungs mucous rales are heard in the
larger bronchi, cavities may be found at any part of these organs, and
points of lobular pneumonia may be detected.
A very serious complication is an inflammation of the heart muscle. This
is shown by a very weak and rapid pulse, great prostration, some filling
of the lungs. This complication nearly always terminates in death. Other
complications which may be mentioned are inflammation of the kidneys,
blood poisoning, congestion of the brain, and inflammation of the
tendinous sheaths and the tendons of the legs.
_Diagnosis._--As fever is the first symptom of infectious pneumonia, it
is useful during an outbreak of this disease to make daily temperature
measurements of the exposed horses, so that the first indication of
disease may be discovered and the horse removed from contact with those
that are sound.
_Prognosis._--The mortality in this disease may be as high as 25 per
cent, but it is usually not more than 10 per cent. If there is a special
tendency to complications of some sort, the mortality is increased.
_Alterations._--At the time of death from infectious pneumonia we
frequently find septic changes and the evidences of putrefaction. The
solidification of the lung tissue is found irregular in shape and high
around the root of the lungs and the large bronchi, and is generally
covered by sound lung tissue. The anterior lobes of the lungs are
usually entirely affected. The diseased portion appears of a
gray-yellowish color, somewhat watery, and tears readily. Matter is
found in the air tubes which form gutters through the jellylike mass of
the diseased lung. Abscesses from the size of a nut to larger masses may
be found throughout the lungs. The blood is dark in color, fluid, or
only clotted into soft, jellylike masses. Masses of gangrenous or
dead-black tissue may be present.
_Treatment._--Bleeding is not to be used, because it would only still
further weaken an already enfeebled animal; antimony or the alterants
would increase the depression of a too-depraved constitution. There is
in this disease no acute congestion of a particular organ to draw off by
depletive measures, nor any violent blood current to be retarded, for
fear of hypernutrition of any special part.
Revulsives do good, as they excite the nervous system and awaken the
torpor of the weakened blood vessels, which aid in the reestablishment
of the functions. As in other diseases, mustard poultices may be applied
over the belly and sides of the chest, but caution must be used in the
employment of blisters, as ugly ulcers may result from their action on a
tissue of weakened vitality. Setons are dangerous from the great
tendency in this disease to septic complications. Repeated friction of
the legs by hand-rubbing and warmth by bandaging and by rubbing the
surface of the body with turpentine and alcohol, which is immediately to
be dried by rough towels, will excite the circulation and stimulate the
emunctories of the skin.
Stimulants are given internally from the outset of the disease.
Turpentine in 1-dram doses regulates the heart and excites the kidneys
to carry off waste matter, but if repeated too frequently may disturb
the already delicate digestive system. Alcohol rectifies the latter
danger, and is a useful stimulant to the heart and digestive system, if
given with care in small doses. It is an antiputrid, and is especially
indicated when septic complications and gangrene are present. The
aromatics and bitter tonics are useful; gentian and tea in warm
decoction form a useful menstruum for other remedies. Digitalis is a
useful remedy. Strychnin and quinin may be given throughout almost the
whole course of the disease. The various preparations of iron are
astringents and excitants to the digestive system. Carbolic acid is an
antiputrid which is of marked benefit in edematous pneumonia; it should
be given in small doses diluted in alcohol.
Salicylic acid may be given in 1 or 2 dram doses every few hours. It is
much used for troubles of the serous membranes, lowers the temperature,
and is of value in this disease in preventing the exudation into the
tissue of the lungs. The alkalines, as the sulphate and bicarbonate of
soda, the nitrate of potash, and very small doses of the iodid of
potash, should be employed to regulate the digestive tract, the kidneys,
and the other excreting glands, and to stimulate absorption of the waste
matter.
The biological products enumerated under the treatment of the catarrhal
form of influenza are also recommended for this disease. The bacterial
vaccines in particular are being employed to a great extent, but the
results are not uniformly satisfactory, especially with regard to
prevention. They might, however, exert a beneficial influence against an
attack of the secondary invaders and complications. A serum is also
being prepared especially for the treatment of this disease, and since
this is obtained from animals which have been highly immunized against
the various organisms found in association with influenza it no doubt is
beneficial, especially when the life of the animal is threatened. Such
serum, however, should be used in sufficiently large doses, as repeated
experience has proved that small doses have no beneficial action on the
disease.
More recently salvarsan is being highly recommended for the treatment of
the pneumonic form of influenza, and by many investigators it is
considered as a specific for this affection. A single injection of this
preparation is supposed to result in a rapid clearing of the lungs and
the recovery of the animal is hastened. The cost of this product,
however, at the present time, is exorbitant, and it should be considered
only in the treatment of very valuable animals.
The same procedure as given for influenza should be carried out in the
prevention of this affection.