34 DISEASES OF THE LARYNX 



Course. — The course of primary roaring is chronic. Due to 

 the increasing atrophy of the crico-arytenoid muscles on the 

 left side the condition grows worse with time. Many roaring 

 horses may be used for light, slow work while others are 

 practically worthless for service. This depends largely upon 

 how deep into the lumen the arytenoid cartilage sinks and 

 whether or not the hypertrophic fellow muscles of the 

 opposite side can act as compensators for the diseased ones 

 of the left. 



Some cases of secondary roaring (forage poisoning, 

 strangles) recover spontaneously in four to six months. 



Prognosis. — About 80 per cent, can be either relieved or 

 cured by surgical interference. 



Treatment. — The most successful treatment "consists in 

 the removal of the laryngeal saccule of the affected side. 



TUMORS IN THE LARYNX. 



Occurrence. — In domestic animals tumors in the larynx 

 are not common. Occasionally we run across them in 

 horses and cattle. The commonest ones are cysts which 

 develop on the anterior surface of the epiglottis or exception- 

 ally below the cricoid cartilage. They attain the size of a 

 hen's egg and are filled with a slimy fluid. Fibromas, 

 lipomas, melanomas, and carcinomas are rare. Chondromas 

 sometimes occur in horses involving the arytenoid and 

 cricoid cartilages and produce symptoms of roaring. Poly- 

 poid tumors occur associated with chronic laryngitis. In 

 cattle tubercular and actinomycotic growths are not 

 uncommon. 



Symptoms. — Tumors of the larynx produce dyspnea and 

 dysphagia. The dyspnea resembles that noted in roaring. 

 It is, however, not infrequently intermittent and occasionally 

 tends to decrease rather than increase on exercise. There 

 is sometimes blood-streaked nasal discharge. A diagnosis 

 can usually be arrived at by palpation through the mouth, 

 the use of the laryngoscope or an exploratory opening of 

 the larynx. The treatment is surgical and consists in the 

 extirpation of the tumor. (See Surgery.) 



Digitized by Microsoft® 



