Predisposing Causes of Roaring. 53 



Our army statistics do not assist us very much in arriving 

 at a conclusion as to age in predisposing to Roaring. Horses 

 rarely receive medical or surgical treatment when they first 

 become affected, and are consequently not reported; the 

 morbid change commencing in many cases very obscurely 

 and gradually increasing, does not, except in severe cases, 

 prevent the horses performing their duty until they are 

 cast, either because of it or of age, or some other disability. 

 Tables III. and lY., therefore, only show horses sold because 

 of Roaring, which in the older ones was no doubt present for 

 many years ; and Table 11. gives the ages of those already 

 affected, but serviceable. 



The influence of age must be considered in relation with 

 the circumstance that young horses are most predisposed 

 to those diseases which are followed by Roaring, adult 

 horses being much less liable to them, and therefore seldom 

 becoming subjects of laryngeal disturbance ; though they 

 suffer far more frequently than young animals from the 

 affections collectively and popularly designated " Broken- 

 wind." 



7. Conformation. 



Certain conformations have been always more or less 

 associated, in the minds of horsemen, with a tendency in 

 horses to become affected with Roaring. 



In this country, horses with long thin necks — "Ewe- 

 necked" — are supposed to be more likely victims than 

 those with better-formed and proportioned necks. Martin^ 

 has supposed that the processes of development of the 

 body in young horses predisposes them anatomically: the 

 heart being pushed farther back and the neck growing 

 correspondingly long, causes the left recurrent nerve to be 

 exposed to extensions and pressure at the aorta, which, he 

 imagines, may impair its conductibility . And Moeller is of the 

 opinion that the frequent appearance of Roaring at from three 



1 Martin, " Oesterreich. Monatsschrift fiir Thierheilkunde," 1885. 



2 Op. cit., p. 34. 



