CHRONIC DISEASES OF THE ORGANS OP RESPIRATION. 229 



Roaring is in some cases hereditary, probably where the make and 

 shape of the sire or dam predispose their progeny to this disease. 



461. High Blowers. 



The noise, which some horses make by flapping the alae of their 

 nostrils, has occasionally been mistaken by inexperienced people for 

 roaring. It has, however, no connection with disease of any sort. It 

 arises from powerful muscular development in the part. If a horse so 

 formed be pushed to his speed and continued at it for some time, it will 

 be seen that he can intermit the noise at his will ; and when he really 

 becomes distressed at the pace, he will have something else to do than to 

 flap about his nostrils, and the sound will then cease altogether. 



462. Grunting. 



Grunts, very similar to those given by roarers when threatened with 

 a blow, are sometimes emitted by horses with big bellies, especially by 

 those just taken up from a straw yard. The cause in such cases may be 

 sudden pressure on the diaphragm from the stomach. Horses also, 

 which have been long in dealers' yards and have been frequently 

 examined as to their wind, will sometimes grunt on being approached, 

 on account of fear of a blow. 



Such grunts have often no connection with roaring; but the horses 

 which emit them should be examined as to their wind with more than 

 ordinary care. Grunting and roaring usually go together, though, as 

 above stated, they may be unconnected. 



WHISTLING. 



463. Nature, seat, and causes of Whistling. 



Whistling is a modification of the noise known as Roaring. The 

 peculiar sound, which is that of air passing through a narrow channel, 

 arises from abnormal contraction in some part of the air passages. The 

 seat of the contraction may be in the larynx, or it may be caused by 

 thickening of the membrane of the windpipe from previous inflammation 

 of that organ. The causes of Whistling are very similar to those of 

 roaring. 



464. Treatment. 



The treatment is similar to that of Roaring. 



In some cases a whistler may be capable of more exertion than a 

 roarer ; but in other cases an opposite result may be found. The public 

 generally attach less importance to whistling than to roaring. 



