RABIES. 545 



they sliould be. The disease is very prevalent in Massachusetts, in 

 New York City, and in some of the Western States. It has been al- 

 most completely eradicated from Pennsylvania and several other 

 States. 



RABIES IX TIIK HORSE. 



[Synonyms: Ilydroiiholii.i. mndiiess ; ///.^■^■(^ (Jrcck ; rayr, French ; initliL-niiik- 



Jtcit, (Jcnu.-in. I 



Definition. — Rabies is a contagious disease which is usually trans- 

 mitted by a bite and by the introduction of a virus contained in (he 

 saliva of an affected animal. It may, however, be transmitted in 

 other ways. It is characterized by symptoms of aberration of the 

 nervous system, and invariably terminates fatally. It is accompanied 

 by lesions, inflammation, and degeneration in the central nervous 

 system. It is a disease that is most common in the dog, but is trans- 

 mitted to the horse, either from dogs or from any other animal 

 affected with it. (See also remarks on page 222.) 



As a disease of the horse it is useless to enter into the etiology fur- 

 ther than to state that in this animal it is invariably the result of the 

 bite of a rabid animal, usually a dog. 



Perhaps no disease in medicine has been the object of more con- 

 troversy than rabies. Certain medical men of prominence have 

 even doubted the existence of the disease. Many medical men have 

 claimed for it a spontaneous origin. The experience, however, of 

 ages has shown that contagion can be proved in the great majority of 

 cases, and, by analogy with other contagious diseases, we may only 

 believe that the development of one case requires the preexistence of 

 a case from which the virus has been transmitted. M. Pasteur has 

 further added to our knowledge of the disease by showing that a 

 virus capable of cultivation exists in the nervous system, especially 

 in the lower part of the brain (medulla oblongata) and in the ante- 

 rior part of the spinal column. M. Pasteur has further shown that 

 that portion of the nervous system which contains the virus, the 

 exact nature of which has not yet been demonstrated, will retain it 

 for a very long time if kept at a very low temperature or if left sur- 

 rounded by carbonic acid; but if the nerve matter, which is virulent 

 at first, is exposed to the air and is kept from putrefaction by sub- 

 stances which will absorb the surrounding moisture, it will gradually 

 lose its virulence ;iiid l)ecoine inotl'ensive in about fifteen days. lie 

 has further shown that the action of a weak virus on an animal will 

 prevent the development of a stronger virus, and from this he has 

 formulated his method of prophylactic treatment. This treatment 

 consists in the successive inoculation of i)ortions of the nerve matter 

 containing the virus from a rabid animal whieh has \)vvn exposed 

 to the atmosphere for thirteen days, ten days, seven days, and four 

 II. Doc. 70.^), 50-2 35 



