History of Roaring. 9 



pathological anatomy, that the morbid conditions giving 

 rise to Roaring began to be seriously investigated. Of 

 course, errors were common at first, and the causes assigned 

 were often more imaginary than real ; but, nevertheless, 

 the real sources of the obstruction causing the noise were 

 anxiously sought for. 



So long ago as 1817, Godine found deformity of the 

 larynx to be, as he supposed, a cause of " cornage."^ 

 Bouley made a similar observation in 1821;^ and Dupuy 

 describes cases in which the glottis was narrowed and 

 deformed, through depression of the left arytenoid cartilage 

 of the larynx. 



In 1825, the first marked step in elucidating the pathology 

 of Roaring, as it is now understood, was made by a very 

 distinguished French veterinarian, Bouley, who, in dissect- 

 ing the carcase of a horse that had been seriously affected, 

 found considerable engorgement of the lymphatic glands at 

 the entrance to the chest (pre-pectoral) ; and observed that 

 the left recurrent nerve, which passed through them on its 

 course to supply the muscles of the larynx, was compressed 

 by these glands and altered in its structure. He had at 

 first imagined that the Roaring had been the result of 

 deformity of the trachea ; but as there was no deformity in 

 this instance, the coincidence of the noise during life with 

 this condition of the nerve found on post-mortem examina- 

 tion, decided his opinion as to the cause of obstructed 

 breathing."^ 



The physiology of the nervous system was beginning to 

 be better understood when these observations were made, 

 and the chief functions of the great nerve of organic life — 

 the vagus — were known, and this knowledge was applied to 

 the elucidation of morbid processes. The very important 

 clinical observation recorded by Bouley, led the veterinary 



1 "Elements d'Hygiene," 1817. 



2 " Compte Rendu d'Alfort " for 1821. 



^ " Recueil de Med. Veterinaire,'' 1825. ^ Ihid., p. 380. 



