76 THEORY AND PRACTICE 



the hip of the animal. This impulse is in direct proportion to the 

 amount of dyspnoea present. This is a valuable point in making 

 your prognosis. In other words, the greater the impulse, the 

 greater the labor in breathing with disastrous consequences. 



The mucous membranes begin to get cyanotic by about the 

 end of the 3rd day. This increases until time of death, when 

 they are livid with an orange tinge. As death approaches, the 

 horse sweats in patches, his extremities get cold, and exhaustion 

 develops rapidly. He persistently stands all through the course 

 of the disease until he drops and dies from asphyxia. 



After the lungs have become solid, under percussion you get 

 a solid dense sound, — no sound except the tubular breathing. 

 Note particularly that there is a difference between pneumonia 

 and hydrothorax. In pneumonia you hear the tubular breathing 

 to the very bottom ; in hydrothorax you hear no sound below the 

 water line. This tubular breathing is a very important symptom 

 in pneumonia, in which it is a diagnostic symptom. No respir- 

 ator}^ murmur can be heard for the air vesicles are full. In 

 such a condition the expired air is usually cold, for it does not 

 stay in the lungs long enough to get warmed up. 



Etiology. — A specific pneumococcus causes an ordinary case 

 in croupous pneumonia. In other cases a bacillus is found, which 

 some bacteriologists consider pathogenic for this disease. But 

 these germs are usually found in the mouth of the healthy ani- 

 mal so that it yields to the action of germs which are constantly 

 present in his mouth. 



A lowered resistence on the part of the animal will allow the 

 bacteria to grow and multiply. Those exciting causes are as 

 follows : 



1. Exposure to cold and wet. If the cold 



is damp, this aggravates the case. 



2. Insufficient ventilation. 



3. Defective cardiac power as seen in pas- 



sive congestion of the lungs. 



4. Inhalation of smoke and irrespirable 



gases. 



5. Foreign bodies taken in through the 



trachea and bronchi. 



