120 Roaring in Horses. 



Sewell, in dissecting the body of a horse which had been a 

 Koarer, found a bony tumour growing from the cervical 

 vertebra between the first ribs, which had exercised pressure 

 on the nerve. ^ 



Many other instances of a similar kind could be given, in 

 which compression of the left recurrent nerve has produced 

 Koaring. In the days when bleeding was fashionable, it was 

 not at ail an infrequent consequence of inflammation of the 

 jugular vein, due to phlebotomy. 



Goubaux was of opinion that harness horses wearing 

 small collars were liable to become affected, as the left 

 recurrent nerve is more superficial at the bottom of the 

 neck than the right one. This is not at all a likely cause, 

 however. 



Some authorities, as K. Giinther, Franck, and others, 

 have favoured the view that the paralysis was related to the 

 course the left recurrent nerve pursues around the posterior 

 aorta ; the pulsations of this great artery are supposed to 

 strain the nerve and weaken its function. But it may be 

 pointed out that the relations between the artery and nerve 

 are the same in horses inhabiting countries in which Roar- 

 ing is unknown. 



Martin- supposed that during the development of the 

 body in youth, the neck becomes lengthened and the heart 

 pushed back, straining the left recurrent nerve and pressing 

 it at the aorta, and so impairing its function. In this way 

 it was attempted to account for the greater frequency of 

 Roaring in horses with long, thin necks ; and Ellenberger, 

 according to Moller, adopting this view, lays stress on the 

 high development of the arterial system and the absence of 

 fat in English thoroughbred horses, whereby the nerve is 

 but little protected at the aorta ; this exposes horses to 

 become Roarers when their condition is fine — as during 

 training. The influence of this arterial pressure in 



^ Percivall, op. cit., p. 253. 



- " Oesterreich. Monatsschrift," 1885. 



