Causes of Chronic Roaring. 119 



In 1846, Lafosse related a case in which a horse at first 

 manifested Roaring at intervals, but soon became continu- 

 ously affected, and the dyspncea finally became so serious that 

 the animal died asphyxiated. At the autopsy the bronchial 

 lymphatic glands were observed to be extremely enlarged, 

 brownish in colour, indurated, adherent to each other and 

 to the lungs, and containing pus at various points, while the 

 pneumogastric nerves were compressed in them, and almost 

 confounded in their mass.i Trasbot^ made many autopsies 

 of horses that had been Roarers, and invariably found that 

 the left recurrent nerve Avas surrounded by indurated, 

 enlarged, or in some other way altered, bronchial lymphatic 

 glands, or was compressed between them and the aorta, and 

 that it was atrophied from its entrance among them ; in 

 some instances it had almost disappeared, or was reduced 

 to a thin gray filament throughout its entire length up the 

 neck. 



Other observers, among them being Dupuy, Bouley, 

 Colin, and Zundel, have noted similar implication of the 

 nerve in these thoracic glands ; and my own examinations 

 of horses which had been affected with Roaring have, in 

 the majority of instances, yielded results the same as those 

 of Trasbot. Bassi reported a case in which a horse was 

 destroyed because of this defect, and an examination 

 showed that the left recurrent nerve had been pressed upon 

 by an enlarged lymphatic gland near the twelfth tracheal 

 ring, and was only one-third its ordinary volume. 



Bouley, so long ago as 1825, found this nerve compressed 

 and altered by engorgement of the pre-pectoral lymphatic 

 glands of horses so affected;^ and F. Gunther records an 

 instance of confirmed Roaring being caused by the left 

 thyroid gland compressing this nerve, and leading to wast- 

 ing of the laryngeal muscles on the same side. Professor 



1 " Journal des Veterimiires du Midi," 1846. 



= " Archives V^terinaires," 1879. 



' " Reoueil de M^decine V^'.t'rinaires," 1826, p. .38. 



