RESPIRATION. 
3 L 1 
minish the caliber of the passages. The pituitary membrane is 
subject to polypi* and steatoma : the latter are sometimes formed 
upon the posterior surface of the velum palati ; in each of 
these cases the inspiration is prolonged, and there is more or less 
roaring in ordinary breathing. If by excitement of the animal 
the breathing is quickened, roaring is heard in expiration as well 
as inspiration, and the former, which before was shorter, is now 
equally prolonged with the inspiration. The glottis conies next 
for consideration. Whatever may tend to lessen the dimension 
of this aperture to the trachea will most certainly affect the respi- 
ration. The various changes arising from disease in this part of 
the respiratory canal are, thickening of the lining membrane ; 
ulceration of it; atrophy and hypertrophy of the laryngeal muscles ; 
ossification of the cartilages forming the glottis ; defective nervous 
influence to the muscles of the larynx; tumours external of the 
glottis, or enlargement of the salivary glands, producing constric- 
tion by pressure : any of these abnormal alterations of structure 
produce an impediment to the ingress and egress of air in respira- 
tion. The inspiration is thereby prolonged in ordinary breathing 
during moderate exertion, but, if the respiration is hurried, the in- 
spiration and expiration are nearly equal. The change in the 
character of the inspiration is accompanied by an increase and 
alteration of the blowing sound natural to the glottis, or a whistling 
or roaring is audible, according to the degree of obstruction 
through the aperture, and the extent of exertion to which the 
horse is submitted. It is remarkable, in all cases of obstruction 
through the glottis, that the inspiration is more difficult than the 
expiration ; and all the irregular or morbid sounds arising from 
disease of the larynx are sounds of inspiration, coughing ex- 
cepted, while those natural to the animal are sounds of expira- 
tion ; such are neighing 4 and snorting. Our best veterinary writer, 
Mr. Percivall, in his Lectures, ascribes snorting to inspiration; 
bul this is an error : it is a long, powerful, and sonorous expiration. 
In all cases of roaring the sound is emitted during inspiration ; 
and it is only under violent continued exertion that a horse can be 
heard to roar in expiration, and even then it is much less audible 
* The French speak of polypi of the nasal membrane. I never saw a case 
myself, but steatoma upon the velum I have witnessed. 
Mr. J. Sewell, of Brighton, had a case of polypus in the right nostril of a 
horse, which he removed by slitting up the ala to the superior angle and 
dragging it away, rupturing the pedicle at its base, and the case did well. — 
The Veterinarian for 1836, p. 400. 
Mr. Brown, of Melton Mowbray, relates a case as occurring in the stomach 
of a horse. — The Veterinarian for 1834, p. 76. 
Mr. Goodworth, of Driffield, gives a case of polypus in the pharynx of a 
marc; and at p. 631 of The Veterinarian for 1831, a contributor under 
the signature T. — Youatt — appears to be quite familiar with them : conse- 
quently there can be no doubt as to the horoe being an animal subject to them. 
