CHAPTER Xm. 



TKOPICAL DISEASES. 



SURRA. 



This disease is caused by the Trypanosoma Evansi, an organism 

 which is a low form of animal life and is found in the blood of affected 

 animals. It attacks and destroys the red blood cells, causing rapid 

 loss of flesh and, sooner or later, death. It is claimed by some au- 

 thorities that the disease originates from the use of water and grass 

 from low lands. 



Symptoms. — Variable temperature, ranging from normal to 102° 

 and even to 106° F. ; dullness; lack of vigor; sometimes swelling of 

 the submaxillary lymph glands; thin, watery discharge from the 

 nostrils; swelHng of the sheath and legs, more frequently the hind 

 ones (Plate XlXa), and swelling along the belly; these swellings pit 

 on pressure. The mucous membrane of the eye, especially of the 

 haw, shows dark-red spots (petechial spots) ; the urine is highly col- 

 ored and is usually passed in large quantities; the bowels are con- 

 stipated in the early stage and profuse diarrhea occurs later. In 

 chronic cases paralysis of the hind extremities takes place, the ani- 

 mal sta^ering when moved. The paralysis may later become com- 

 plete and the horse will be unable to rise. In the acute type of the 

 disease the animal dies in twelve or fifteen days, while in the chronic 

 case he may linger for one or two months. The diagnosis is com- 

 plete only when a microscopic examination of the blood discloses the 

 parasite (Plate XX). As a rule, the parasite is seen only when the 

 temperature is considerably elevated. 



Surra is always fatal, and as the danger to other animals is great 

 on account of its highly ctmtagious nature, all animals that have 

 been proved to have the parasite in the blood should be removed at 

 once from contact with healthy stock and destroyed. The carcasses 

 should be saturated with oil and burned. Measures to prevent the 

 spread of the disease should always be enforced. When in a district 

 infested with surra the temperature of horses should be taken regu- 

 larly every two or three days. Any animal showing, without a 



