60 Roaring in Horses, 



respiration ; 2. The difficulty in breathing (dysjmoea) ; 3. 

 The character of the cough. In man, the alteration in or 

 loss of voice (aphonia) is an early and characteristic 

 symptom, but this is, of course, absent in the horse ; and 

 therefore the veterinary surgeon has not the advantage of 

 it as an aid in the detection of laryngeal paralysis at an 

 early stage, nor as a diagnostic sign. 



1. Stridor. 



In the great majority of cases, the existence of this 

 paralysis is first ascertained by the noise the horse makes 

 when undergoing exertion, or when made suddenly to 

 inspire ; but it is, as a rule, when in more or less rapid 

 motion that the abnormal sound is first perceived. In 

 healthy or physiological respiration, when the horse is at 

 rest and the ear is held near the animal's nostril, a faint 

 blowing or puffing sound can be heard, which is somewhat 

 prolonged during inspiration, not so long, but louder in ex- 

 piration. This gentle soft sound is produced by the air 

 passing through the larynx and air-passages of the head ; it 

 can be heard more distinctly if the ear be closely applied to 

 the trachea, and loudest of all in the region of the larynx. On 

 exertion, this sound is increased, though not nearly so much 

 in horses which are in good training or condition, as in 

 those which are not so, or are very fat, or have the abdomen 

 voluminous — as animals fed on bulky food, or pregnant 

 mares— such are said to be " thick-winded ;" but however 

 much its diapason may be raised, this sound is still normal. 

 In Roaring the sound is different— or it may be said that 

 another sound is added to it — when circumstances cause 

 the respiration to be increased, and the compound noise 

 then emitted is indicative of an altered state of the 

 laryngeal cavity. 



The timbre, or tone, and the intensity of the new sound, 

 vary considerably with the changes in the larynx which 

 give rise to them. While the horse is at rest the sound is 



