“When air only moderately vitiated is breathed continuously for a
greater length of time the results are still very injurious, and in the
front rank of diseases so caused stand pulmonary consumption, and other
destructive affections of the lungs. Perhaps no better example of this
can be given than that of the monkey houses of the Zoological Gardens of
London and Paris. While these houses were small and ill-ventilated the
monkeys died in large numbers from pulmonary consumption, but after they
had been enlarged and better ventilated the mortality from this cause
nearly ceased. (Arnott.)”
“Town dairy cows which are packed in close ill-ventilated buildings and
never allowed to go out are very subject to consumption, while horses
kept in no better conditions, but spending nearly half their time in the
open air, rarely have phthisis. (With lung plague it will be remembered
that the out-door exercise and mingling of herds leads to an increase of
the mortality.) Horses newly stabled suffer severely from diseases of
the lungs. The same holds true of human beings. A long list of careful
observers have noticed the essential connection of lack of ventilation
and pulmonary consumption. Baudelacque, Carmichael, Arnott, Lepelletier,
Allison, Sir James Clark, Toyubee, Guy, Greenhow, Sir Alexander
Armstrong, Parkes, and Aitken have especially insisted upon consumption
being a sequence of lack of ventilation. Dr. Cormac indeed insists with
great force that consumption is originated by rebreathed air.”
“The notorious prevalence of consumption in sailors has been directly
traced to the impure air in which they sleep, and an extensive outbreak
of lung disease (not tubercular), leading to destruction of lung tissue,
in the English Mediteranean squadron in 1860 was clearly traced by Dr.
Bryson to the contamination of the air. In a nursery hospital at Dublin
with entire neglect of ventilation, 2,944 children died in four years,
whereas after the ventilation had been improved only 279 died in the
same length of time.”
“Parkes (Practical Hygiene) says:
“‘But not only phthisis may be reasonably considered to have one of its
modes of origin in the breathing of an atmosphere contaminated by
respiration, but other lung diseases, bronchitis and pneumonia, appear
also to be more common in such circumstances. Both among seamen and
civilians working in confined, close rooms, who are otherwise so
differently circumstanced, we find an excess of the acute lung
affections.’
“In this connection, the statement of the air breathed by an ox per hour
and that supplied him on board a ship with insufficient ventilation or
none may be instructive. The ox takes in with each breath about 5 liters
of air. This is at the rate of 50 liters per minute, or 3,000 per hour =
105.9 cubic feet. This amount of air is therefore rendered all but
irrespirable by each animal in the course of an hour. And this, be it
noted, is by breathing alone, and makes no account of the contamination
by perspiration in the overheated hold, and by the emanations from the
accumulating excrement.”
“On board the steamers we have found the space allotted to each bullock
to vary from 150 to 240 cubic feet. On the steamship “Holland,” loaded
at New York, August 21, 1881, we found the stalls amidships allowed the
full space of 240 cubic feet per head. In the bow where there was less
height between the decks the space was considerably less. On the lower
deck, where 129 cattle were accommodated, the space allowed each was
217.4 cubic feet. The port-holes in the upper deck were nine inches in
diameter and there was one for each pair of stalls—central and
lateral—or for eight oxen. These being well above the water line would
be available for ventilation in ordinary weather. The port-holes in the
lower deck, similarly arranged, were about two feet above the water
line, and consequently not available for ventilation, save in
exceptionally calm weather. The temperature on the main deck of this
ship (between the outer and main deck), when only half the cattle had
been loaded, was in the neighborhood of 90° although she was lying in
the center of the North River with port-holes and hatches open, and a
fresh breeze blowing from the north.”
“On the ‘Assyrian Monarch’ the space per head was only 192 cubic feet,
but this ship was supplied with a ventilating fan or blower capable of
delivering over 50,000 cubic feet of fresh air per hour, so that her
ventilation was abundantly provided for. In some smaller ships we found
the space per head to exceed little, if at all, 150 cubic feet. In
these, accordingly, a single hour without any change of air would
threaten the life of every animal on board, and two hours would endanger
those for which even the larger space is provided. It is true that such
absolute seclusion is rarely required, and that a certain amount of
ærial diffusion is always going on through imperfectly closed hatches,
companion ways, and ventilators, yet that these are often insufficient
has been amply shown by such losses as are reported above, as well as by
the bronchitis and tuberculosis which Drs. Whitney, Lyman, and Williams
have found in the lungs of American animals arriving in England.”
“ORGANIC MATTER IN EXPIRED AIR.”
“The decomposing organic matter given off by the lungs and skin is
probably the most injurious of the animal excreta, when allowed to act
on the system for a length of time. This exhaled organic matter is
easily recognized in the air by chemical tests, or by the putrid odor
evolved when cotton wool, that has been breathed through, is left to
soak in otherwise pure water at a temperature of 70° to 80° Fahrenheit.
The experiments of Gavarret and Hammond, in which expired air had its
carbonic acid and water vapor removed, leaving only the organic matter,
showed that the latter was highly deleterious. Hammond found that a
mouse died in forty-five minutes in such an atmosphere. It has also been
again and again demonstrated that air containing a given amount of
carbonic acid as the result of respiration is far more poisonous than
air which contains the same amount of carbonic acid as a product of
combustion.”
“WATER VAPOR IN EXPIRED AIR.”
“The amount of water vapor given off by the lungs varies greatly
according as the air is already more or less saturated with water. As
the air in the stalls between decks is always saturated with water
vapor, we may take the very lowest estimate for each animal, namely, 60
ounces in 24 hours, which for a cargo of 200 head would amount to over
93 gallons. And this is in addition to the exhalations from the skin and
the bowel and kidney excretions. The air between decks is therefore
constantly saturated with moisture which condenses and runs down in
streams on every solid object. Among the ill effects of this saturation
may be noted:”
“First. The saturation of the air with water vapor increases the
exhalation of carbon dioxide from the lungs. This effect on the
excretion of carbonic acid is usually so great as to counterbalance the
tendency of warm air to reduce the production of this acid. This
saturation, therefore, with water increases the danger of suffocation by
the accumulation of the irrespirable carbon dioxide in the ship, unless
the air is being constantly removed.”
“Second. The excess of moisture in the warm atmosphere hastens the
decomposition of the organic matter derived from the lungs, skin, and
manure. Sir Alexander Armstrong, head of the medical department of the
British Navy, says: “There can be no more fertile source of disease
among seamen, or, indeed, other persons, than the constant inhalation of
a moist atmosphere, whether sleeping or waking; but particularly is this
influence injurious when the moisture exists between a ship’s decks,
where it may be at the same time more or less impure, and hot or cold,
according to circumstances.” It has become an aphorism with sanitarians
that “a damp ship is an unhealthy ship,” and many instances are adduced
in which a sufficient renewal of the air between decks, with or without
stoves to dry it, has transformed a naval pest-house into a salubrious
vessel.”
“All such considerations must emphasize the demand for such a constant
renewal of air between decks on steamers carrying cattle as shall serve
to obviate all those conditions of ill-health, with congestion and
inflammation of the lungs, as have proved in the past a serious drawback
to our foreign cattle-trade. To accomplish this and at once remove from
between decks the excess of carbon dioxide, of decomposing organic
matter, and of humidity, and to furnish air approaching in purity and
dryness that of the atmosphere outside, we can conceive of nothing more
simple and effective than thorough ventilation by fan or heat
extraction, as referred to below.” Report of the U. S. Treasury Cattle
Commission, 1882.
The above quotations were written with special reference to cattle but
the author reproduces them here as in principle applicable to horses as
well.
In both horses and cattle treated as above it is common to find ingesta
in the bronchia drawn in during the violent paroxysms of coughing. Here
we have a direct mechanical irritant and a means of septic infection,
highly calculated to induce unhealthy broncho-pneumonia. Williams quotes
the case of a horse in which vomition was caused by an over dose of
aconite, and a portion of the food entered the bronchi.
In this connection must be named the introduction into the bronchia of
liquids forcibly administered to horses and cattle. In the horse the
length of the soft palate enables him to hold liquids in the mouth
during his pleasure, and among the expedients adopted to coerce him are
the very dangerous ones of holding the nostrils and of pouring the
liquid through the nose. When the nostrils are held the urgent demand
for air leads to attempts to breathe through the mouth, and, whether he
succeeds in this or not, the usual result is the drawing of a portion of
the liquid into the lungs. When it is poured through the nose the animal
cannot protect himself except by rapid gulping, and as he must breathe,
a portion of the liquid is usually drawn into the lungs. Any irritant
taken in this way will develop bronchitis, and some bland agents like
melted lard are almost equally injurious. Cattle having a short palate
can scarcely resist swallowing liquids that are poured into the mouth,
but a cough with the succeeding quick inspiration will almost certainly
draw a portion into the bronchia. To return to the influence of cold,
exposed situations which receive the full force of cold winds, those
from the north and west on the Atlantic slope are specially conducive to
bronchitis. Exposure of newly clipped animals to stand without
protection in winter or early spring, has the same tendency. Finally the
inhalation of smoke or of heated and irritant gases and vapors, as in a
burning building, is an effective factor.
_Symptoms_: In its _mildest form_ bronchitis is a transient illness with
some dullness, impaired appetite, hot, dry mouth, redness of the visible
mucous membranes, a moderately strong, resonant cough, attended with
slight pain, slight rise of temperature, accelerated breathing and
pulse, and mucous discharge from the nose. Such an attack passes over in
a few days and without any medicinal treatment if ordinary precautions
are taken to avoid a repetition of its causes.
In _severe cases_ the symptoms are more intense from the first. Besides
the dullness and inappetence, hot, dry mouth, generally increased
temperature of the body (102° to 104° F.), accelerated and labored
breathing, and other manifestations of fever, there are more specific
symptoms. The cough is dry, hard, painful, often paroxysmal, and appears
as if it came from the very depth of the chest. A strong, harsh,
bronchial sound is heard over the lower end of the trachea and the upper
border of the middle third of the chest just behind the shoulder.
Percussion detects no change from the natural resonance of the chest,
nor auscultation any crepitating sound. Pressure in the intercostal
spaces causes no suffering. The expired air feels hot. The pulse though
accelerated is moderately soft and sometimes even weak, a condition
which marks inflammations of mucous membranes as contrasted with those
of the serous. The mucous membrane of the nose has a dark red hue,
especially when the inflammation extends to the smaller ramifications of
the bronchial tubes so as to impair the æration of the blood. In the
same state there is excessive dullness and prostration because of the
supply of partially venous blood to the brain. The head is held low, the
nose often supported upon the manger, and the eyelids are semi-closed
and injected.
From the second to the fourth day a free exudation takes place from the
surface of the mucous membrane, and the symptoms are materially changed.
The cough becomes more frequent but softer, looser, and attended with a
rattle from the air passing through the abundant mucous secretion. The
cooing or tubal sound heard at the lower end of the windpipe and behind
the shoulder has now given place to a _mucous râle_. A nasal discharge
appears at first watery, thin, of a whitish, glairy froth, but soon
becoming more opaque, white, milky and flocculent and having little
tendency to stick to the nostrils. This is often expelled with sneezing
and accompanied by movement of the jaws. With the access of free
secretion there is a great mitigation of the fever and the other
distressing symptoms, and, if no relapse nor complication supervenes,
recovery may be complete in a fortnight or three weeks from the onset.
From this time all the febrile symptoms decline and disappear, appetite
and liveliness return, the discharge rapidly diminishes and finally
disappears, when the patient may be said to have completely recovered.
=Capillary and pseudo-membranous bronchitis= are described by Reynal as
occurring in young horses recently brought into the army and subjected
to the hot and close stables in some of the French barracks. It began as
ordinary bronchitis, which in place of tending to recovery, propagated
itself to the most minute bronchial ramifications, and was frequently
complicated by the formation of false membranes. The signs of its
accession are an extreme intensity of the general symptoms, the rapid,
labored, difficult breathing, accompanied by convulsive action of the
pectoral and abdominal muscles; the frequent, painful, suffocating and
abortive cough, which violently shakes the whole body; the extended
head, open mouth, distorted nostrils, reddish brown protruding eyes; the
pinched, haggard features, and the frothy mucous, nasal discharge
striated with blood, and later interspersed with shreds of false
membrane similar to those existing in croup. In connection with these
are the symptoms of extreme oppression, partial sweats, tumultuous
action of the heart and small, weak, rapid pulse. Death resulted from
suffocation during a paroxysm of coughing.
_Course._ _Duration._ _Termination._ Bronchitis is not usually fatal,
except in very young or old or worn out animals, or unless it assumes
the _capillary_ form or is complicated by pneumonia, pulmonary abscess
or by metastasis to the bowels or feet. In the mildest cases health is
re-established in three or four days, and in the severe, about the
twelfth, fifteenth or twentieth day. In old and debilitated animals in
which pure bronchitis proves fatal, the abundant effusion into the
bronchial tubes, the influence of gravitation retaining this in the
smaller tubes, the palsy of the cilia which normally carry it outward,
and the want of power to expectorate by coughing, usually bring about
suffocation. This is favored by the non-ærated state of the blood, which
rapidly prostrates the already weakened nervous centres. The
supervention of pneumonia will be marked by a new class of symptoms,
especially labored breathing, dullness on percussion and crepitation on
auscultation. The susceptibility of the bowels is so great in some cases
of bronchitis, particularly in those associated with a low fever, that
superpurgation, enteritis and death may result from the smallest dose of
laxative medicine,—the author has seen a fatal result from the
administration of two drachms of aloes in a case of this kind. In such
circumstances the skin usually participates in an equal degree, and
though the superpurgation be checked an extension of the disease to the
feet may still prove fatal or induce such changes of structure as to
leave the animal practically worthless. In old animals or after repeated
severe attacks of bronchitis it may merge into the _chronic_ form.
_Thick wind_ is a frequent sequel of severe cases from thickening or
dilatation of the bronchial tubes, from collapse of the lung or from
emphysema.
_Postmortem appearances._ In the bodies of animals that have died of
bronchitis the air passages within the lungs are filled with a white or
greenish yellow mucus. If this is washed from the tubes by a stream of
water, the mucous membrane is often found to be injected, studded more
or less profusely with red points or with branching red lines, and with
petechia, and the mucous membrane is softened, sometimes thickened and
friable. When, however, the bronchitis has been attended by a free
purulent expectoration the mucous membrane may, when washed, show no
perceptible alteration from the healthy standard as examined by the
naked eye.
In the _capillary form_ the blocking up of the smaller tubes by a
tenacious frothy mucus, and by the false membranes which form complete
casts of many of the tubes and the partial consolidation (collapse) of
circumscribed pyriform masses of lung tissue with which such tubes
communicate form the chief features on examination after death.
This state of _consolidation_ or _collapse_ of lung is frequently seen
in simple bronchitis as well. It is then due to the blocking up of one
or more bronchia by plugs of tenacious mucus which act as valves,
preventing the entrance of air, though it may permit of its easy passage
outward. This state of lung differs materially from the consolidation
due to inflamed lung tissue (hepatisation). When cut it does not present
the granular appearance of the latter, caused by the exudation into the
minute air cells, but the cut surface has an uniform homogeneous aspect
aptly likened by Lænnec to _muscular flesh_ (splenisation). Mendelson,
Traube and Gairdner have induced artificial collapse of the lung by
introducing foreign bodies into the bronchia of animals.
_Emphysema_ of the margins of the lung is a frequent concomitant of
_collapse_. The cause is plain. The portion of lung, the subject of
collapse, emptied of its air, does not occupy a tithe of the space it
would normally fill. The rest of the lung tissue expands unduly to fill
out the vacated portion of chest and the cells become overdistended and
ruptured. The emphysematous lung is known by its lighter color, by its
irregular bulging surface, by the subsidence of these elevations when
pricked with a needle, and by a more marked crepitation when pressed.
When the cells have burst and the air escaped into the areolar tissue
between the lobes, it appears as dark lines circumscribing small
portions of pulmonary tissue and collapsing when pricked.
_Treatment._ The mildest cases will recover of themselves, especially if
care is taken to protect the patients against cold, wet, draughts of
cold air, over-exertion, and other injurious causes, and to give a part
of the food warm and sloppy. In severe cases treatment must be more
active, but it will be borne in mind that severe depletive measures are
badly endured. Bleeding dangerously increases the already existing
weakness and prostration without affording any corresponding advantage.
It is only admissible when from the severity of the symptoms in the
early stages suffocation is threatened or when the brain becomes
involved in disease.
Causing the patient to inhale water vapor from scalded bran or hay is to
be assiduously carried on for half an hour to an hour twice or thrice
daily until expectoration has been freely established and the cough and
fever alike moderated. The density of the vapor must of course be
apportioned to the particular case so as to avoid any approach to
suffocation. The addition of the fumes of burning sulphur will often by
their astringent and antiphlogistic action on the mucous membrane,
render the vaporous application more effective. A pinch put into a small
piece of paper twisted at one end to prevent burning of the fingers may
be set fire to and the fumes allowed to pervade the apartment so that
they can be breathed freely without inducing cough. A mustard poultice
to the neck and sides of the chest should also be applied and kept on an
hour or until effusion into the skin is well marked by thickening of its
substance. Injections of warm water should be given alike to check or
obviate shivering and to equalize the general temperature and to solicit
the action of the bowels. In sporadic cases with active fever and full
strong pulse a laxative dose of aloes (3 to 4 drachms) may be given, but
if with a low fever and during the prevalence of influenza not more than
half the dose should be given or enemata alone may be relied upon. As
soon as the medicine has set or at once if it is withheld, neutral salts
may be given (Liquor Ammoniæ Acetatis 2 oz. or Sweet Spirits of Nitre 1
oz. or nitrate of potass ½ oz. combined with 10 drops tincture of
aconite repeated twice or thrice daily). If the cough is troublesome and
secretion long in being established, expectorants may be used (oxymel of
squill 3 oz., powdered squill ½ oz. or liquorice 1 drachm) with half the
doses of the neutral salts.
In the early stages to hasten expectoration such preparations as the
following may be given:
Recipe: Potas. Bicarb. 2 ounces; Ammon. Carb. 2 ounces; Digitalis Pulv.
2 drams. Mix. Divide into eight powders: give one every four hours.
Recipe: Ammon. Murias. 2 ounces; Choral. Hydrat. 1 ounce; Tinct.
Hyoscam. 2 fluid ounces; Aqua 8 fluid ounces. Mix. Give two
tablespoonfuls every four hours.
Apomorphia, tartar emetic, turpentine or benzoin may be employed or even
pilocarpin, care being taken not to increase prostration unduly.
Compressed air, oxygen and peroxide of hydrogen will sometimes relieve.
With the advent of expectoration, or earlier, iodide of potassium in one
drachm dose, thrice a day will do much to obviate glandular and other
enlargement which would tend to develop _roaring_.
The diet should be laxative, non-stimulating and somewhat spare. Mashes
of wheat bran, boiled linseed or boiled barley; roots such as turnips,
carrots, beets; in summer a limited supply of fresh grass, with little
hay at any time and that scalded, may indicate the nature of the
aliments to be used. As a beverage chilled fresh water or linseed tea
may be supplied _ad libitum_.
Should the nasal discharge manifest no disposition to cease at the end
of 15 or 20 days, as will sometimes happen in young horses, stimulants
and tonics must be employed. Gentian (4 drachms), Sulphate of iron (2
drachms), Arsenious acid (5 to 10 grains) or nux vomica (1 scruple) may
be given daily as ball, electuary or powder. A full and nutritive diet
should at the same time be allowed, and open air exercise enjoined.