Common Diseases of Farm Animals

by Robert Alexander Craig

PNEUMONIA.—Inflammation of the lungs is more common in horses than in any of the other domestic animals. The croupous form is the most common. The inflammation may affect one or both lungs, one or more lobes, or scattered lobules of lung tissue. The inflammation may be acute, subacute or chronic.

The causes are very much the same as in other respiratory diseases. Exposure to cold and wet, stable draughts, becoming chilled after perspiring freely and washing the animal with cold water are the common causes of pneumonia. Inflammation of the lungs is especially apt to occur if the animal is not accustomed to such exposure. Animals affected with other respiratory diseases are predisposed to pneumonia. Drenching animals by way of the nostril and irritating drenches, or regurgitated feed passing into the air passages and lungs are the traumatic causes of pneumonia.

The symptoms vary in the different forms of pneumonia. In case pneumonia occurs secondarily, the earliest symptoms are confounded with those of the primary disease. The first symptoms noticed may be a high body temperature, as indicated by chills, and refusing to eat. The visible mucous membranes are red and congested, the nostrils dilated, the respirations quickened and difficult, the expired air hot and the pulse beats accelerated. The animal coughs, and in the horse, a rusty discharge may be noticed adhering to the margins of the nostrils. The horse refuses to lie down if both lungs are inflamed. In severe cases the expression of the face indicates pain, the respirations are labored, the general symptoms aggravated, and the animal stands with the front feet spread apart. Cattle are inclined to lie down, unless the lungs are seriously affected. Hogs like to burrow under the litter.

The course of croupous pneumonia is typical, and unless it terminates fatally in the first stage, the periods of congestion, hepatization and resolution follow each other in regular manner. Auscultation of the lungs is of great value in diagnosing and watching the progress of the disease. It is more difficult to determine the character of the lung sounds in the horse and cow than it is in the small animals. This is especially difficult if the animal is fat. During the period of congestion which lasts about a day, one can hear both healthy and crepitating sounds. The period of hepatization is characterized by an absence of sound over the diseased area. The inflammatory exudates become organized at the beginning of this stage, and the air can not enter the air cells. This period lasts several days. Resolution marks the beginning of recovery or convalescence. Toward the end of the second period, the inflammatory exudate in the air cells has begun to degenerate. In the last stage, these exudates undergo liquefaction and are absorbed, or expelled by coughing, in from seven days to two weeks, depending on the extent of the inflammation and the general condition of the animal.

In the subacute form the symptoms are mild and may subside within a week. Sometimes abscesses form in the lung. Gangrenous inflammation of the lung can be recognized by the odor of the expired air and the severity of the symptoms. This form of pneumonia terminates fatally. If the larger portion of the lung tissue is inflamed, death from asphyxia may occur in the second stage.

The success in the treatment of pneumonia depends largely on the care. Properly ventilated, clean, comfortable quarters and careful nursing are highly important. Large animals should be given a roomy box stall. Cold does not aggravate pneumonia, providing the animal's body is well protected with blankets and the limbs bandaged. Wet, damp quarters and draughts are injurious. Hogs should be given plenty of bedding to burrow in. A light, easily digested diet should be fed. Very little roughage should be fed. If the animal does not eat well, it may be given eggs and milk. Weak pulse beats should be treated by giving digitalis and strychnine. Counterirritation to the chest wall is indicated. During convalescence, bitter tonics may be given. Constipation should be treated by giving the animal castor or linseed oil.

PLEURISY.—Inflammation of the pleura is most common in horses. It occurs in all farm animals and is frequently unilateral. There are two forms of pleurisy, acute and chronic. Pleuropneumonia is common when the cause is a specific germ. This occurs in tuberculosis, pleuropneumonia of horses and pneumococcus infection.

The common causes are exposure to cold, chilling winds, draughty, damp quarters, and drinking cold water when perspiring. Injuries to the costal pleura by fractured ribs and punctured wounds may cause it to become inflamed.

The early symptoms of acute pleurisy are chills, rise in body temperature, pain and abdominal breathing. The most characteristic symptom is the ridge extending along the lower extremities of the ribs (pleuritic ridge). The animal does not stand still as in pneumonia, but changes its position occasionally, its movements in many cases being accompanied by a grunt. Pressure on the wall of the chest causes the animal to flinch and show evidence of severe pain. Large animals rarely lie down. The cough is short and painful. On placing the ear against the wall of the chest and listening to the respirations, we are able to hear friction sounds. After a few days effusion occurs in the pleural cavity. Although the animal may have refused to eat up to this time, it now appears greatly relieved and may offer to eat its feed. This relief may be only temporary. If the fluid exudate forms in sufficient quantity to cause pressure on the heart and lungs and interfere with their movement, the pulse beat is weak, the respirations quick and labored, the elbows are turned out and the feet are spread apart. All of the respiratory muscles may be used. The expression of the face may indicate threatened asphyxia. We may determine the extent of the pleural exudate by auscultation. There is no evidence of respiratory sounds in that portion of the chest below the surface of the fluid. Dropsical swellings may occur on the under surface of the breast and abdomen.

In subacute cases evidence of recovery is noted in from four to ten days. Acute pleurisy very often terminates fatally. Under the most favorable conditions, recovery takes place very slowly, sometimes extending over a period of several months. It is not uncommon for the horse to continue having "defective wind."