THE EFFECT OF RABIES ON ANIMALS 43^5 



It is a filterable virus which attacks the central nervous system. 

 This virus can be found in the salivary glands and in the saliva of 

 infected animals. 



If some of the nervous tissue of an animal that has died from 

 the disease or been killed during the course of the disease be ex- 

 amined microscopically, characteristic spherical inclusions will be 

 found. These structures are called Negri bodies and the appear- 

 ance of them in the brain cells is the principal method of determin- 

 ing whether or not a suspected animal is rabid. If the}^ are found 

 in the brain of an animal which has bitten a human being, the 

 Pasteur treatment is immediately prescribed for the person or 

 animal bitten. The relation of these Negri bodies to the causa- 

 tive organism is not yet known. To confirm the diagnosis, a bit 

 of the brain of the dead animal is sometimes injected into an- 

 other animal. If the disease is rabies, the second animal will 

 become sick and die. Because the rabies organism attacks the 

 central nervous system, the muscles controlled by that system 

 are secondarily affected and, consequently, paralysis is a charac- 

 teristic of the disease. 



The effect of rabies on animals. When a dog becomes sick 

 with rabies, only an expert would suspect what the trouble is. 

 Many cases do not show violent symptoms, although most cases 

 begin with a characteristic change in the animal's disposition. In 

 general, the course of the disease is marked by a change in dis- 

 position, irritability and excitement, which is usually followed 

 by depression, paralysis, and death. 



Transmission. Rabies is transmitted to man by the bite of an 

 infected animal, because the germs or virus of the disease are in 

 the saliva. The bite breaks the skin and introduces the causative 

 organism. There have been cases in which persons contracted 

 the malady from being scratched by the animals or from allowing 

 the dogs to lick a hand upon which some scratch or wound 

 existed. 



