532 



of propagation and reproduction of others of its own kind if placed in 

 the proper media. 



When we come to stndy the etiology of glanders, the difference of 

 susceptibility on the part of difiEerent species of animals, or even on 

 the part of individuals of the same species, and when we come to find 

 proof of the slow incubation and latent character of the disease as 

 it exists in certain individuals, we will understand how in a section of 

 country containing a number of glandered animals others can seem 

 to contract and develop the disease without having apparently been 

 exposed to contagion. 



Etiologjj.—The contagious nature of glanders, in no matter what 

 form it appears, being to-day definitely demonstrated, we can recog- 

 nize but one cause for all cases, and that is contagion by means of the 

 specific virus of the disease. 



In studying the writings of the older authors on glanders, and the 

 works of those authors who contested the contagious nature of the dis- 

 ease, we find a large number of predisposing causes assigned as factors 

 in the development of the malady. 



While a virus from a case of glanders if inoculated into an animal 

 of the genus equus vnll inevitably produce the disease, we find a vast 

 difference in the contagious activity of the products of different cases 

 of glanders. We find a great variation in the manner and rapidity 

 of the development of the disease in different individuals, and we 

 find that the contagion is much more apt to be carried to sound ani- 

 mals under certain circumstances than it is under others. Only cer- 

 tain species of animals are susceptible of contracting the disease, and 

 while some of these contract it as a general constitutional malady, in 

 others it only develops as a local sore. 



In acute glanders the contagion is found in its most virulent form, 

 as is shown by the inevitable infection of susceptible animals inocu- 

 lated with the disease, while the discharge from chronic semilatent 

 glanders and farcy may at times be inoculated with a negative result; 

 again, in acute glanders, as we have a free discharge, a much greater 

 quantity of virus-containing matter is scattered in the neighborhood 

 of an infected horse to serve as a contagion to others than is found in 

 the small amount of discharge of the chronic cases. 



The chances of contagion are much greater when sound horses, 

 asses, or mules are placed in the immediate neighborhood of glandered 

 horses, drink from the same bucket, stand in the next stall or work in 

 the same wagon, or are fed from the same bales of hay or straw which 

 have been impregnated by the saliva and soiled by the discharge of 

 sick animals. The contagion must terminate by direct contact of the 

 discharges of a glandered animal with the tissues of a sound one, 

 either on the exterior or when swallowed mixed with food into the 

 digestive tract. 



Glanders is not infectious in the old acceptation of the word. Re- 

 nault made a large number of experiiuents, forcing sound horses to 



