60 THEORY AND PRACTICE 



flesh rapidly and dies in from 2 to 4 weeks from septicemia. 

 The fetor of this expiring air is so marked that you can smell 

 it plainly. 



90% of the cases of bronchitis in the third stage die and it 

 is safe to say that at least 90% of the cases that do not run 

 beyond the second stage recover. In cattle acute bronchitis is 

 more apt to prove fatal than in horses. 



Special Pathology. — In the first stage the ciliary epithelium 

 is ruffled up producing the sensation of rawness that we feel in 

 such cases and the mucous membrane is intensely congested. 



In the second stage the effusion of serum increases and there 

 is a secretion of degenerated mucous that coagulates more or 

 less. This serum macerates the attachments of the ciliary 

 epithelium and they become loose and float out with the dis- 

 charge leaving the surface unprotected. If the disease is con- 

 fined to the bronchi no further development will take place un- 

 less it goes on to the third stage, which is that of suppuration. 

 In that case some suppuration will take place and probably 

 ulceration. This ulceration in all probability leads to a fatal 

 termination by absorption of the putrefactive matter. In cases 

 of bronchitis the effusion is drawn back by inspiration, leading 

 to the plugging of the bronchioles. This condition is spoken of 

 as "occlusion." In some cases some of the thinner portion of 

 the effusion or mucous may be forced back into the vesicles. 

 The air in the vesicles at the ends of the occluded bronchioles 

 becomes absorbed. In that case the vesicles collapse, which 

 constitutes atelectasis, producing what is known as ''fetal lung." 



Post Mortem. — There are three stages in bronchitis in which 

 horses may die. One is when the eff'usion in the bronchi is ex- 

 cessive, filling the smaller bronchi and the horse dies from 

 asphyxiation, practically in the same condition as an animal 

 would be under water. In bronchitis with effusion the medium 

 sized bronchi are full and the horse practically drowns. The 

 second is when he goes into the third stage and dies from septi- 

 caemia. Third, when he has bronchiolitis with occlusion and 

 atelectasis. 



The post mortem characteristics are as follows: The large 

 bronchi are about half filled, we will say, with a frothy, bloody, 



