DISEASES OF THE RESPIRATORY ORGANS. (continued 2)

TUBERCULOSIS OF THE LUNGS.

Pulmonary consumption or tuberculosis has been recognized in the horse in a number of instances. The symptoms are as of chronic pneumonia or pleurisy. There is no treatment for the disease.

HEAVES, BROKEN WIND, OR ASTHMA.

Much confusion exists in the popular mind in regard to the nature of heaves. Many horsemen loosely apply the term to all ailments where the breathing is difficult or noisy. Scientific veterinarians are well acquainted with the phenomena and locality of the affection, but there is a great diversity of opinion as regards the exact cause. Asthma is generally thought to be caused by spasm of the small circular muscles that surround the bronchial tubes. The continued existence of this affection of the muscles leads to a paralysis of them, and the forced breathing to emphysema, which always accompanies heaves.

Heaves is usually associated with disorder of the function of digestion or to an error in the choice of feed. Feeding on clover hay or damaged hay or straw, too bulky and innutritious feed, and keeping the horse in a dusty atmosphere or a badly ventilated stable produce or predispose to heaves. Horses brought from a high to a low level are predisposed.

In itself broken wind is not a fatal disease, but death is generally caused by an affection closely connected with it. After death, if the organs are examined, the lesions found depend much upon the length of time broken wind has affected the animal. In recent cases very few changes are noticeable, but in animals that have been broken-winded for a long time the changes are well-marked. The lungs are paler than natural, and of much less weight in proportion to the volume, as evidenced by floating them in water. The walls of the small bronchial tubes and the membrane of the larger tubes are thickened. The right side of the heart is enlarged and its cavities dilated. The stomach is enlarged and its walls stretched. The important change found in the lungs is a condition technically called pulmonary emphysema. This is of two varieties: First, what is termed "vesicular emphysema," which consists of an enlargement of the capacity of the air cells (air vesicles) by dilation of their walls. The second form is called interlobular, or interstitial, emphysema, and follows the first. In this variety the air finds its way into the lung tissue between the air cells or the tissue between the small lobules.

Symptoms.—Almost every experienced horseman is able to detect heaves. The peculiar movement of the flanks and abdomen point out the ailment at once. In recent cases, however, the affected animal does not always exhibit the characteristic breathing unless exerted to a certain extent. The cough which accompanies this disease is peculiar to it. It is difficult to describe, but the sound is short and something like a grunt. When air is inspired—that is, taken in—it appears to be done in the same manner as in health; it may possibly be done a little quicker than natural, but not enough to attract any notice. It is when the act of expiration (or expelling the air from the lungs) is performed that the great change in the breathing is perceptible. It must be remembered that the lungs have lost much of their elasticity, and in consequence of their power of contracting on account of the degeneration of the walls of the air cells, and also on account of the paralysis of muscular tissue before mentioned. The air passes into them freely, but the power to expel it is lost to a great extent by the lungs; therefore the abdominal muscles are brought into play. These muscles, especially in the region of the flank, are seen to contract, then pause for a moment, then complete the act of contracting, thus making a double bellowslike movement at each expiration, a sort of jerky motion with every breath. The double expiratory movement may also be detected by allowing the that the expiratory current is not continuous, but is broken into two jets. When the animal is exerted a wheezing noise accompanies the breathing. This noise may be heard to a less extent when the animal is at rest if the ear is applied to the chest.

As before remarked, indigestion is often present in these cases. The animal may have a depraved appetite, as shown by a desire to eat dirt and soiled bedding, which he often devours in preference to the clean feed in the trough or manger. The stomach is liable to be overloaded with indigestible feed. The abdomen may assume that form called "potbellied." The animal frequently passes wind of a very offensive odor. When first put to work dung is passed frequently; the bowels are often loose. The animal can not stand much work, as the muscular system is soft. Round-chested horses are said to be predisposed to the disease, and it is certain that in cases of long standing the chest usually becomes rounder than natural.

Certain individuals become very expert in managing a horse affected with heaves in suppressing the symptoms for a short time. They take advantage of the fact that the breathing is much easier when the stomach and intestines are empty. They also resort to the use of medicines that have a depressing effect. When the veterinarian is examining a horse for soundness, and he suspects that the animal has been "fixed," he usually gives the horse as much water as he will drink and then has him ridden or driven rapidly up a hill or on a heavy road. This will bring out the characteristic breathing of heaves if the horse is so afflicted, but will not cause the symptoms of heaves in a healthy horse. All broken-winded horses have the cough peculiar to the affection, but it is not regular. A considerable time may elapse before it is heard and then it may come on in paroxysms, especially when first brought out of the stable into the cold air, or when excited by work, or after a drink of cold water. The cough is usually the first symptom of the disease.

Treatment.—When the disease is established there is no cure for it. Proper attention paid to the diet will relieve the distressing symptoms to a certain extent, but they will undoubtedly reappear in their intensity the first time the animal overloads the stomach or is allowed food of bad quality. Clover hay or bulky feed which contains but little nutriment have much to do with the cause of the disease, and therefore should be entirely omitted when the animal is affected, as well as before. It has been asserted that the disease is unknown where clover hay is never used. The diet should be confined to feed of the best quality and in the smallest quantity. The bad effect of moldy or dusty hay, fodder, or feed of any kind can not be overestimated. A small quantity of the best hay once a day is sufficient. This should be cut and dampened. The animal should invariably be watered before feeding; never directly after a meal. The animal should not be worked immediately after a meal. Exertion, when the stomach is full, invariably aggravates the symptoms. Turning on pasture gives relief. Carrots, potatoes, or turnips chopped and mixed with oats or corn are a good diet. Half a pint to a pint of thick, dark molasses with each feed is useful.

Arsenic is efficacious in palliating the symptoms. It is best administered in the form of a solution of arsenic, as Fowler's solution or as the white powdered arsenious acid. Of the former the dose is 1 ounce to the drinking water three times daily; of the latter one may give 3 grains in each feed. These quantities may be cautiously increased as the animal becomes accustomed to the drug. If the bowels do not act regularly, a pint of raw linseed oil may be given once or twice a month, or a handful of Glauber's salt may be given in the feed twice daily, so long as necessary. It must, however, be borne in mind that all medicinal treatment is of secondary consideration; careful attention paid to the diet is of greatest importance. Broken-winded animals should not be used for breeding purposes. A predisposition to the disease may be inherited.

CHRONIC COUGH.

A chronic cough may succeed the acute disease of the respiratory organs, such as pneumonia, bronchitis, laryngitis, etc. It accompanies chronic roaring, chronic bronchitis, broken wind; it may succeed influenza. As previously stated, cough is but a symptom and not a disease in itself. Chronic cough is occasionally associated with diseases other than those of the organs of respiration. It may be a symptom of chronic indigestion or of worms. In such cases it is caused by a reflex nervous irritation. The proper treatment in all cases of chronic cough is to ascertain the nature of the disease of which it is a symptom, and then cure the disease if possible and the cough will cease.

The treatment of the affections will be found under their appropriate heads, to which the reader is referred.

PLEURODYNIA.

This is a form of rheumatism that affects the intercostal muscles; that is, the muscles between the ribs. The apparent symptoms are very similar to those of pleurisy. The animal is stiff and not inclined to turn round; the ribs are kept in a fixed state as much as possible. If the head is pulled round suddenly, or the affected side struck with the hand, or if the spaces between the ribs are pressed with the fingers, the animal will flinch and perhaps emit a grunt or groan expressive of much pain. It is distinguished from pleurisy by the absence of fever, cough, the friction sound, the effusion into the chest, and by the existence of rheumatism in other parts. The treatment for this affection is the same as for rheumatism affecting other parts.

WOUNDS PENETRATING THE WALLS OF THE CHEST.

A wound penetrating the wall of the chest admits air into the thoracic cavity outside the lung. This condition is known as pneumothorax and may result in collapse of the lung. The wound may be so made that when the walls of the chest are dilating a little air is sucked in, but during the contraction of the wall the contained air presses against the torn part in such manner as entirely to close the wound; thus a small quantity of air gains access with each inspiration, while none is allowed to escape until the lung is pressed into a very small compass and forced into the anterior part of the chest. The same thing may occur from a broken rib inflicting a wound in the lung. In this form the air gains access from the lung, and there may not be even an opening in the walls of the chest. In such cases the air may be absorbed, when a spontaneous cure is the result, but when the symptoms are urgent it is recommended that the air be removed by a trocar and cannula or by an aspirator.

It is evident that the treatment of wounds that penetrate the thoracic cavity should be prompt. It should be quickly ascertained whether or not a foreign body remains in the wound; then it should be thoroughly cleaned with a solution of carbolic acid, 1 part in 40 parts of water. The wound should then be closed immediately. If it is an incised wound, it should be closed with sutures or with adhesive plasters; if torn or lacerated, adhesive plaster may be used or a bandage around the chest over the dressing. At all events, air must be prevented from getting into the chest as soon and as effectually as possible. The after treatment of the wound should consist principally in keeping the parts clean with a solution of carbolic acid, and applying fresh dressing as often as required to keep the wound in a healthy condition. Care should be taken that the discharges from the wound have an outlet in the most dependent part. (See Wounds and their treatment, p. 484.) If pleurisy supervenes, it should be treated as advised under that head.

THUMPS, OR SPASM OF THE DIAPHRAGM.

"Thumps" is generally thought by the inexperienced to be a palpitation of the heart. While it is true that palpitation of the heart is sometimes called "thumps," it must not be confounded with the affection under consideration.

In the beginning of this article on the diseases of the organs of respiration, the diaphragm was briefly referred to as the principal and essential muscle of respiration. Spasmodic or irregular contractions of it in man are manifested by what is familiarly known as hiccoughs. Thumps in the horse is similar to hiccoughs in man although in all cases the peculiar noise is not made in the throat of the horse.

There should be no difficulty in distinguishing this affection from palpitation of the heart. The jerky motion affects the whole body, and is not confined to the region of the heart. If one hand is placed on the body at about the middle of the last rib, while the other hand is placed over the heart behind the left elbow, it will be easily demonstrated that there is no connection between the thumping or jerking of the diaphragm and the beating of the heart. In fact, when the animal is affected with spasms of the diaphragm the beating of the heart is usually much weaker and less perceptible than natural. Thumps is produced by causes similar to those that produce congestion of the lungs and dilatation or palpitation of the heart, and may occur in connection with these conditions. If not relieved, death usually results from congestion or edema of the lungs, as the breathing is interfered with by the inordinate action of this important muscle of inspiration so much that proper aeration of the blood can not take place. The treatment should be as prescribed for congestion of the lungs, and, in addition, antispasmodics, such as 1 ounce of sulphuric ether in warm water or 3 drams of asafetida.

RUPTURE OF THE DIAPHRAGM.

Post-mortem examinations after colic or severe accident sometimes reveal rupture of the diaphragm. This may take place after death, from the generation of gases in the decomposing carcass, which distend the intestines so that the diaphragm is ruptured by the great pressure against it. The symptoms are intensely difficult respiration and great depression. There is no treatment.