“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.