480 GENERAL DISEASES. 



it broke out in the Eastern Provino© early in January. It is 

 usually at its worst in April, and as a rule disappears with the 

 first frost in May, Edington states that it begins about the end 

 of October in the Transvaal and Rhodesia. " In Natal it gene- 

 rally begins on the sea-coast a little before Christmas ; at Maritz- 

 burg, about February; and up country, somewhat later. March 

 and April are the worst months. Occasional cases are met with 

 even in the winter on the coast. One undoubted instance occurred 

 near Ladysmith during the Boer war in 1881, in July or August, 

 when the ground was covered with snow" (Wiltsliire). 



TRANSMISSION FROM ONE HORSE TO ANOTHER HORSE. 



— Experience amply proves that the disease is never, under natural 

 conditions, communicated from one horse to another horse. '' It 

 is only directly contagious ; for while horses may be inoculated 

 with virulent blood and be permitted to die among clean animals, 

 I have never found, during observations extending over seven 

 years, a single case of infection from such a source " (Edington). 

 Inoculation with the blood serum which is discharged from the 

 nostrils of an infected horse, will produce the disease in many 

 cases, but not always. Drenching with the blood of an infected 

 horse appears to invariably convey the disease. Experience 

 warrants the statement, that horses suffering from this malady are 

 capable of infecting healthy pastures, and in this way would in- 

 directly infect other horses. 



CAUSE. — There is no doubt that the virus of this disease is 

 transmitted to the horse almost always by means of damp grass. 

 The influence of dew or damp on grass is shown by the frequent 

 occurrence, during an outbreak, of cases of this disease among 

 horses which are allowed to graze while dew is on the herbage, 

 and by the almost absolute protection afforded by restricting the 

 animals to the consumption of dry fodder. It is instructive to 

 note that horse sickness is almost unknown in South African 

 racing stables, the animals of which seldom, if ever, get green 

 grass when in training. The same remark applies, with more or 

 less correctness, to the stabled horses of South African mail coach 

 lines, which are fed on dry food and which enjoy a marked im- 

 munity from this disease, even when animals at grass in the 

 vicinity are dying from it in large numbers. Dr. Edington, who 

 has done far more than anyone else in the investigation of this 

 disease, tells us that " horses which are kept in the stable during 

 the night are, as a rule, safe, but during last year (1899) 60 per 

 cent, of the stabled horses in Eshowe, Zululand, died of this 

 sickness. Veterinary-Lieutenant Coley, A.V.D., who kindly made 

 the observations for me, stated that these horses were mainly fed 



