INFECTIOUS DISEASES 229 



Rabies 



Rabies occurs in swine, but is not prevalent. It may 

 occur enzootically, but is much more likely to affect only 

 one animal, or few animals at most, in any one locality. 



Etiology. Rabies is caused by a virus, but the exact 

 nature of this virus has not been determined more than 

 that it is filterable. Recently it has been successfully 

 cultivated. 



Source and manner of infection. The usual 

 source of rabies in swine is from an infected animal, 

 usually a dog. Rabid dogs meandering through the 

 country occasionally attack swine, biting and thus infect- 

 ing them. 



Lesions. Gross lesions are absent in swine that have 

 died of rabies. Foreign substances may be found in the 

 stomach, but swine have a habit of consuming almost 

 anything and therefore foreign bodies in the stomach 

 has little significance. Microscopically, Negri bodies 

 are found in the cells of the amnion horn, and also in the 

 cells of the cerebellar cortex. These bodies are the same 

 in swine as in other animals. 



Symptoms. Affected swine usually become excitable 

 and show sexual desire, and they may become vicious 

 and attack other animals or man. They have a depraved 

 appetite, or there may be inappetence. These symptoms 

 will become more aggravated for two or three days, then 

 the animal becomes depressed and paralysis of various 

 groups of muscles appears. The affected animals may 

 be depressed from the beginning, soon evidence more or 

 less of paralysis, and finally assume a comatose state 

 prior to death. 



Diagnosis. Diagnosis cannot be made positive by 

 clinical examination, although if the history shows con- 

 tact with a rabid animal from ten days to four weeks 

 before the symptoms appeared one could diagnose the 

 case as suspected rabies. A positive diagnosis can be 

 made only by the finding of Negri bodies by microscopic 

 examination, or the reproduction of the disease by inocu- 



