52 THEORY AND PRACTICE 



CHRONIC LARYNGITIS. 



Under this head come nearly all the conditions producing 

 noisy breathing — roaring, whistling, wheezing, thick wind, 

 chronic cough, and paralysis of the throat. 



Etiology. — These chronic conditions generally follow some 

 acute disease of the throat, but they may not. Roaring, for ex- 

 ample, is due to paralysis of a nerve ; whistling may be caused 

 by a certain anatomical conformation; wheezing, diseases of the 

 nostrils ; thick wind may follow bronchial diseases ; chronic 

 cough — anything; paralysis of the throat may follow acute 

 laryngo-pharyngitis. 



Roaring. — Roaring is due to the paralysis of the left recur- 

 rent laryngeal nerve. As a result we get paralysis of certain 

 arytenoid muscles. These are the arytenoideus, thyro-arytenoideus, 

 crico-arytenoideus, and the crico-arytenoideus posticus. In this 

 condition the muscles atrophy and change their red, fleshy color 

 to that of pale yellow or amber. As a result the arytenoid cartil- 

 age drops into the larynx and obstructs inspiration. Expiration 

 is performed with these, but in inspiration, the rima glottis may 

 be almost closed by the obstructing cartilage. 



Symptoms. — These consist of loud roaring sounds in breath- 

 ing, great difiiculty in respiration, — may be so great as to choke 

 the horse until he drops. But the animal does not die from 

 asphyxia ; when he goes down, the recumbent position helps re- 

 store respiration. So long as the horse is quiet, there is no dif- 

 ficulty in breathing, but the roaring occurs during exercise. As 

 a rule, roaring ruins the horse, although the famous Eclipse was 

 a roarer. 



Whistling. — This is a sharp shrill sound on a high key. It 

 is sometimes produced by diseases of the throat. It can be 

 produced mechanically. A horse with narrow jowls harnessed 

 with a curb bit, under the tap of the whip will produce pressure 

 on the larynx so that it becomes constricted, and this may cause 

 whistling. 



Wheezing. — This disease is not necessarily connected with 

 the larynx, it may be in the nose. It may be caused by neoplasm 

 of the septum nasi, polypus in the nostrils, fracture with 



