HISTORY 



323 



cent tissue at once. The application of caustics and disinfect- 

 ants makes matters infinitely worse, as they stimulate the 

 tissues to renewed growth-activity. In Florida the disease 

 affects only the genus equinus. " 



In 1896, some of the diseased tissue from cases of this 

 affection in Florida, were sent to the Bureau of Animal Indus- 

 try for investigation. They were studied by Fish, who made 

 an extended report on the results of his findings. He also 

 gave a very complete review of the literature. 



Hodgson, in 1853, referred to the sores as cancerous ulcers 

 and Hart, in 1872, was strongly inclined to pronounce it 

 cancer, although he could not confirm this view structurally 

 by microscopic examination of the tissue. It seems to. be 

 generally accepted that the disease is peculiar to the Tropics, 

 but cases have been reported in Kansas and Minnesota in the 

 United States, not only during the summer months, but when 

 the thermometer registered below zero. We might also expect 

 that the disease would exist in Mexico and Central and South 

 American countries, where the conditions of temperature and 

 moisture are favorable. 



Reports show that a high temperature is essential for the 

 development of the disease, although exceptional cases are 

 noted as occurring during the cold season. Moisture does not 

 seem to be necessary, since many cases develop when the sea- 

 son is dry. It is, however, an important factor. Statistics 

 show that cases are more numerous and that the disease 

 assumes a more aggravated form during the wet season. 



In India, native as well as foreign bred horses are sus- 

 ceptible, but according to some writers, none of the other 

 equine species is affected. 



In the United States mules and cattle are said to develop 

 it, but not so readily as the horse. Outbreaks among cattle 

 are comparatively rare. Thin-skinned animals are more sus- 

 ceptible than thick-skinned ones. Some discrepancy of 

 opinion exists as to the kind of horses most likely to take the 

 disease (assuming that bursattee and leeches are similar). 

 Neal states that only horses of good blood leech, and the 



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