246 THE HORSE IN HEALTH AND DISEASE 



heal, characteristic star-shaped scars are left to mark their loca- 

 tion. 



A positive diagnosis is made by inoculating the suspect with 

 mallein, either subcutaneously or by introducing it into the eye. 

 Tests on the blood-serum may be made in doubtful cases to clinch 

 the diagnosis. 



Treatment is seldom warranted, first, because few recoveries 

 follow, and, secondly, for the reason that once a horse becomes 

 infected he is a source of danger to others with which he comes in 

 contact, even after all visible symptoms of the disease have disap- 

 peared; therefore, it is deemed advisable to immediately destroy 

 all affected animals. 



RABIES 



Rabies is an acute, infectious, and communicable disease affect- 

 ing particularly the central nervous system. To date no specific 

 organism has been discovered. However, it has been conclusively 

 proved that a filterable virus is the exact and only cause. The 

 disease is almost always communicated through the inoculation of 

 the saUva from a rabid dog. A variable period of incubation is one 

 of the characteristics. 



Among the first symptoms are restlessness and hypersensitive- 

 ness. Later the animal becomes furious, and viciously bites and 

 kicks at any object within reach. The course of the disease is five 

 or six days. Paralysis and death are the inevitable end. Little 

 difficulty should be had in differentiating rabies from other ner- 

 vous disorders, as in none of them does the horse exhibit the same 

 symptoms of maliciousness. If any doubt exists, small pieces of 

 the brain should be examined by aid of the microscope for the 

 presence of Negri bodies. When found these bodies are considered 

 positive evidence of the disease. In the horse they are very small 

 and usually confined to limited areas. 



So far as the horse is concerned there is no treatment. In man 

 an immune serum has been used with success. 



DOURINE 



Dourine is an infectious disease of the horse and ass, transmitted 

 by the act of copulation and caused by a protozoan parasite, the 

 Trypanosoma equiperdum, which is found as an actively motile 

 organism in the blood. 



