102 THE MODERN HORSE DOCTOR. 



produce distortion of the larynx or windpipe ; the result is^ then 

 the same. 



Roaring may also be occasioned by pressure on the throat 

 from tumors, &c, from tonic spasm, and from atrophy of the 

 parts. We have always supposed that the seat of roaring was 

 confined to the upper respiratory passages ; but the following case, 

 related by Mr. Percivall, goes to show that the lungs may be- 

 come its seat. " A horse was treated for violent roaring. JThe 

 neck was repeatedly blistered ; it was even fired ; but still no 

 relief. So painful was it to hear the animal roar, when he was 

 even gently led out of the stable, that bronchotomy was had re- 

 course to, but without avail. At length, seeing the animal suf- 

 fered so much pain and distress in breathing, and that the case 

 appeared altogether insusceptible of being relieved, it was de- 

 termined to destroy him. On examination, no thickening of the 

 laryngeal or tracheal membrane appeared, nor, in fact, any other 

 disease of those parts ; but the lungs were hepatized throughout 

 their substance, and the smaller divisions of the bronchial tubes 

 in many places so compressed that they were hardly pervious." 



To prove the nervous origin of roaring, Mr. Field made the 

 following experiment : " Having ascertained that the organs of 

 respiration of a horse used for farming purposes were sound, I 

 cast him, and laid bare the recurrent nerve of the off side, and 

 passed a ligature loosely around it ; he was then allowed to get 

 up, and, after a few minutes, galloped severely without evincing 

 the slightest defect in his breathing. The nerve was then drawn 

 out by the ligature, and one inch and a half of it excised ; and 

 immediately on only trotting the horse a short distance, such a 

 degree of roaring was occasioned, that, had the exertion been 

 continued, he would soon have fallen. 



" I kept this horse four years, and though his breathing became 

 much better, he continued a sad roarer ; at the end of that time 

 I destroyed him, for the purpose of procuring the larynx, which 

 exhibited the usual condition of wasted muscles (atrophia) on the 

 side deprived of the influence of the recurrent nerve." 



Treatment of Roaring. — The intelligent reader will here per- 

 ceive, that in the majority of cases very little hopes can be enter- 

 tained of a cure, and in fact, the defect cannot be cured unless we 



