ROARING. 105 



seen before; one cause of somewhat rare occurrence is a polypics 

 orpolyphoid tumor situate in the upper part of the nasal passage; 

 thickening of the mucous membrane which covers the walls of the 

 nose, resulting from chronic catarrh or cold, a condition which 

 materially lessens the calibre or size of the nasal passage, and 

 which after exertion is apt to become rather more swollen and so 

 still further diminish the size of the air passage and produce a 

 wheezing sound extremely perplexing to a young practitioner 

 anxious to do his duty by his client; he readily observes the noise, 

 but does not consider it sufficiently pronounced to indicate roaring, 

 and in this he is correct, but the doubt still remains as to the 

 cause; a speculum might probably reveal something to assist one 

 in arriving at a conclusion, but the facilities for applying this test 

 are rarely available; moreover as it would involve casting the 

 horse, it is very improbable the seller would permit such a course 

 to be adopted; hence all that can be said is the horse makes a 

 noise! Horses with short, thick necks, having Vao. parotid glands 

 very fully developed will not infrequently make a noise as bad as 

 the worst roarer during a test gallop, while all the time there is 

 no defect in the larynx; we consider this to be due to the turgid 

 and swollen condition of the parotid glands, as the result of the 

 quickened circulation, the glands pressing upon the opening of 

 the larynx through the position of the horse's head, his nose 

 being drawn into his chest while hard held, and the size of the 

 respiratory passage materially constricted; such an animal without 

 a beajing rein, would do ordinary work in harness at a fair trot 

 and give no evidence of making a noise; this sort of exercise 

 would not excite the circulation sufficiently to cause any disturb- 

 ance. We nsxt come to the larynx itself for diseased conditions 

 other than the chief and most acute one already referred to in- 

 volving an alteration in the shape of the organ by reason of struc- 

 tural defects; these are mainly due to inflammation, such as oc- 

 curs in laryngitis, already dealt with in the previous chapter; this 

 form of inflammation affects the other tissues which go to form 

 the vocal organ, such as cartilage the component parts or some of 

 them being united as the result of inflammation and thus altering 

 entirely the shape of the larynx or the connectiv^e tissue which 

 serves to keep the various cartilaginous parts in position which 



