I 



EOARINa. 383 



liardly ever become roarers. On the other hand, I have known in- 

 stances, in Egypt and India, of horses becoming roarers when 

 liberally fed on ordinary chopped straw, the ends of which would 

 probably have an irritating eti'ect on the mucous membrane of the 

 mouth, gullet and stomach. The animals in question were either 

 Enoflish horses or Australian horses which, were descended from 

 English parents, and were therefore more or less predisposed 

 to this complaint. As I could find no cases of roaring produced 

 in this manner among Egyptian, East Indian, and Arab horses 

 which were fed under similar conditions, I conclude that this 

 manner of feeding can produce the disease only in conjunction with 

 a predisposing influence, such as that of heredity. Many expe- 

 rienced stablemen in England consider that hay given in large 

 quantities is a well-marked cause of roaring, especially if it contains 

 a considerable proportion of rye grass, which is rich in woody fibre. 

 The proportion of woody fibre in hay is much higher if the grass 

 is cut late, than if it is harvested early in the season, say, in the 

 beginning of June ; and also varies according to the amount of 

 fermentation that takes place during the process of drying. Heavy 

 cart-horses in Scotland and in the North of England, many of which 

 are given large quantities of straw to eat, are almost as subject to 

 roaring .as are thorough-breds. Here, the fact that they are of 

 great size (p. 385) has a strong predisposing influence. 



Experience justifies the remark that, other conditions being equal, 

 horses which are fed on green grass are not so liable to roaring as 

 those which are kept on hay or straw, especially if it is chopped. 

 It is instructive to note that if straw is chopped so fine as to allow 

 it to be readily swallowed without being well masticated, it is 

 much more liable to cause indio;estion than if it is cut at a lencrth 

 of, say, four or five inches. 



PREDISPOSING CAUSES OF ROARING PARALYSIS.— 1. J 

 cold, damp climate is undoubtedly the chief predisposing cause in 

 this disease, evidently by its influence in producing diseases of the 

 organs of breathing. In fact, the liability to contract roaring in a 

 country, other conditions being equal, is directly proportionate to 

 the tendency of horses in that climate to catch colds and coughs. 

 No country, however, is absolutely free from this disease, which 

 is common in the cold, damp climate of Great Britain and Ireland, 

 but is almost unknown in the warm climates of India, Egypt, Syria, 

 Arabia, Persia, South xA.frioa, and, I believe, in South America. 

 During an eighteen years' residence in India, I found only two 

 or three cases of roaring among the many thousands of Arab horses 

 I met, and about the same number in Indian-bred horses. It is true 

 that the majority of Arabs are under 14.2; but many of the Indian 



