DISEASES OF THE RESPIRATORY SYSTEM. 123 



animal down a run, and if he is a whistler he will show it. Drawing 

 heavy loads, especially in mud or snow, will often cause the sound 

 to be heard. In some cases the sound can be detected by ausculta- 

 tion over the trachea when the horse is at rest. 



What is the prognosis ? 



Depends a gi-cat deal on the cause; the prognosis is usually 

 grave as regards a cure. 



In some few cases relief may be afforded and the animal able 

 to do slow, easy work. The disease is slow in its course. 



Outline the treatment. 



Tracheotomy or laryngotomy may be resorted to, but the tubes, 

 being foreign bodies, produce a great deal of inconvenience; again, 

 the air enters directly into the lungs, possibly filled with dust, etc., 

 and is not heated. 



Sometimes blistering is used; also, electricity and strychnine; 

 but there seems to be no satisfactory way of treating this trouble. 



If tubes are put in permanently, they have to be taken out 

 every three or four , weeks or of tener, the parts and tubes thor- 

 oughly cleansed, and the same or another tube replaced. 



A resection of the vocal cords, called arytenectonuj, has been 

 resorted to and has met with varying success. 



4. DISEASES OF THE BRONCHI. 



BRONCHITIS. 



Define bronchitis. 



Bronchitis is essentially an inflammation of the mucous mem- 

 brane of the larynx, trachea, and bronchial tubes (the large or 

 small). 



What are the forms of bronchitis ? 



Clinically and pathologically, l)ronchitis in the horse may be 

 divided into acute catarrhal bronchitis of the large tubes, 



CHRONIC catarrhal BRONCHITIS, ACUTE CAPILLARY BRONCHITIS, 

 BRONCHIECTASIS. 



