468 GENERAL DISEASES. 



only directly contagious ; for while horses may be inoculated with 

 virulent blood and be permitted to die among clean animals, 

 during observations extending over seven years, a single case of 

 infection from such a source was never found. Inoculation with 

 the blood serum discharged from the nostrils of an infected horse 

 will produce the disease in many cases, but not always. Drencli- 

 ing with the blood of an infected horse appears to invariably 

 convey the disease. Experience warrants the statement, that 

 horses sufiering from this malady are capable of infecting healthy 

 pastures, and in this way would indirectly 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 enjoy a marked immunity 

 from this disease, even when animals at grass in the vicinity are 

 dying from it in large numbers. Dr. Edington states that horses 

 kept in the stable during the night are, as a rule, safe, but during 

 the year 1899 60 per cent, of the stabled horses in Eshowe, Zulu- 

 land, died of this sickness. Veterinary-Lieutenant Coley, A.V.D., 

 who kindly made the observations for him, stated that these 

 horses were mainly fed on G-uinea'or Ubaaba grass, mixed with 

 forage (oaten hay) or Indian com. This grass was usually out in 

 the evening and made into bundles next day. Those who took 

 particular care to have the grass thoroughly dried in the sun 

 before using it, did not lose their horses, while those who neglected 

 this precaution lost heavily. While in South Africa, I heard from 

 reliable authorities, of several cases of stabled horses, during an 

 outbreak, contracting the disease, apparently from being fed on 

 grass which was cut and freshly brought to them ; while those 

 wJiich were in the same stable, but which were kept on dry food, 

 remained healthy. 



Some South African horse-owners believe that night air in the 

 open acts as a carrier of this disease, and consequently will not 

 work their animals after the sun has set. This precaution appears 

 to be absolutely unnecessary a.s regards the prevention of horse 

 sickness. The coach horses to which I have recently alluded, work 



