DISEASES OF THE RESPIRATORY APPARATUS 99 



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 respira- 

 tions are labored, the general symptoms aggTavated, and the 

 animal stands with the front feet spread apart. Cattle are in- 

 clined to lie down, unless the lungs are seriously affected. ITogs 

 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 gTeat value in diagnosing and 

 watching the progTess 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 be- 

 come 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 sub- 

 side within a w^eek. 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. 



