144 MANUAL OF EQUINE MEDICINE. 



In the early stages, when the large bronchi are specially 

 affected, loud, sonorous rhonchi may be heard over the 

 anterior part of the chest, and also behind the scapula, 

 at the upper and middle thirds of the chest. If the smaller 

 ramifications be involved, sibilant rales are heard ; they 

 are of higher pitch, and wheezing and hissing in character. 

 The milder forms of bronchitis yield no physical signs 

 of importance. 



As the disease progresses, there is secretion of viscid 

 mucus from the bronchial mucous membrane, and the sounds 

 in consequence become moist, being modified by the pass- 

 ing of the air through the bubbles of mucus. In the large 

 bronchi, where the sonorous rhonchi were heard, large cre- 

 pitations or mucous rales, as they are sometimes called, are 

 now audible in their stead. In the smaller tubes lesser 

 crepitant sounds or sm^art sibilant rales are heard. 



In cases where the deeper and more sonorous sounds are 

 in excess of the high-pitched sibilant rales, the disease is 

 mainly confined to the large bronchi, and the smaller 

 ramifications are entirely free. The prognosis in such cases 

 is more favourable. 



When the smaller bronchi are especially affected, the ex- 

 pirations are much prolonged, and the prognosis is more 

 serious. 



In some cases one or several bronchi may be blocked 

 up, and thus portions of the lung may collapse, and 

 consolidation, atrophy, and pulmonary emphysema may be 

 induced. 



As the disease progresses there is expectoration of a 

 scanty, ropy, tenacious mucus. The discharge escapes to 

 some extent through the nose, but the greater part passes 

 into the mouth, and is swallowed. In the later stages, how- 

 ever, a profuse discharge escapes through the nostrils. The 

 cough becomes more violent and frequefit than at first, but 



