434 DISEASES OF THE RESPIRATOEY ORGANS. 



infiltration of the membranes, these not being much elevated 

 but occupying a considerable s^oace, the sound is of a whisthng 

 or sibilant character. 



This is apt to be confounded with noise of a similar charac- 

 ter originating at some other point of the air-passages, and by 

 propagation, detected at a distance from its place of origin. 

 Generally we may distinguish between these abnormal sounds 

 originating in the upper and lower air-passages by carefully 

 auscultating from the nasal chambers downwards. When 

 originating in the sinuses of the head, they will be found to de- 

 crease in pitch as we proceed downwards. 



There is a sound often heard in examining horses, of which 

 it behoves us to be cognisant ; it is that of a tolerably loud flap- 

 ping or fluttering noise proceeding from the nasal cavities, 

 emitted when a horse is made to execute rapid movement, 

 sometimes — but we think wrongly — styled 'high-blowing.' This 

 sound, which is heard when trotting or cantering, but disappears, 

 when the horse has settled down to a good and steady gallop, 

 is to be regarded rather as a peculiarity connected with the 

 muscular arrangement of the nostrils ; probably the actual 

 noise is the result of flapping or quivering of a voluntary 

 character of the false nostrils. It may be intermittent, but 

 usually disappears when the animal has been galloped for some 

 time. It ought not to be regarded as unsoundness. 



In laryngeal disease, where w^c have a lessening of the orifice, 

 there is an audible increase in pitch and duration of the sound. 

 When the mucous membrane is considerably inflamed, with 

 infiltration of the submucous tissue, considerable tumefaction 

 and lessening of the cavity of the larynx, with an extra amount 

 of mucus on the membrane, we have a soft humid sibilant 

 rale or whistle ; this sound, it may be observed, is of an inter- 

 mittent character, being most distinct when the amount of 

 mucus in the larynx is greatest, and less observed when by 

 coughing the mucus is dislodged. 



Another sound of a somewhat similar character, but not 

 moist, a dry sibilant Avheezing or whistling sound characterized 

 by its steady persistent nature, is indicative of a narrowing of 

 the aperture of the larynx, it may be from compression, distor- 

 tion, or approximation of the cartilages or vocal cords, the 

 result of nervous disease. 



