Predisposing Causes of Roaring. 57 



The bearing-rein has long been considered a powerful 

 agent in injuring the larynx, and so leading to impaired 

 respiration. Percivall, fifty years ago, said of Eoaring 

 horses : " A large proportion of these subjects are harness- 

 horses, whose necks have been rainbowed by the bearing- 

 rein for hours together, and whose larynges have been 

 compressed and tracheas distorted by this unnatural and 

 constrained position of the head and neck." And subse- 

 quent writers have insisted as strongly upon the injury! 

 done by the injudicious use of this article of harness. But! 

 though it may, and does, cause much pain and discomfort i 

 to horses, yet it is very questionable if it does distort the \ 

 larynx or trachea, or produce Eoaring. Saddle-horses are 

 more liable to become Roarers than carriage-horses, so farj 

 as my experience leads me to judge, and they do not wear: 



bearing-reins. 



9. Accidental Causes. 



What may be considered as the accidental predisposing i 

 causes of Chronic Roaring may also be regarded as the 

 most frequent, if not the almost constant exciting, causes 

 of the imperfection. The occasional causes I have already 

 alluded to, and among them are some which I believe are 

 in operation in a very great majority of the cases of Roar- 

 ing, and especially of horses predisposed by heredity or other 

 tendencies to become Roarers. I refer to the contagious 

 and infectious suppurative fever of early age — Strangles, 

 which is followed so very often by Roaring ; also inflamma- 

 tion of the air-passages, or fevers affecting these or the 

 membrane lining the chest (pleura). 



Among our army horses. Strangles certainly holds the 

 first place in predisposing or exciting to Roaring, among 

 remounts especially, and respiratory diseases come next. 

 In the French army it is somewhat the same, if we refer to 

 the evidence which Charon adduces. That good observer had 

 opportunities for studying this matter which few, if any, of 



