DISEASES OF HORSES 65 



lungs, of the testicles, of the internal organs, and of the subcutaneous 

 connective tissue. 



Glanders was imported into America at the close of the eight- 

 eenth century, and before the end of the first half of the last century 

 had spread to a considerable degree among the horses of the Middle 

 and immediately adjoining Southern States. This disease was un- 

 known in Mexico until carried there during the Mexican war by the 

 badly diseased horses of the United States Army. During the first 

 half of the last century a large body of veterinarians and medical 

 men protested against the contagious character of this disease, and 

 prevailed by their opinion to such an extent against the common 

 opinion that several of the governments of Europe undertook a series 

 of experiments to determine the right between the contesting parties. 



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

 of susceptibility on the part of different 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. 



Causes. The contagious nature of glanders, in no matter what 

 form it appears, being today 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. The causative organism is known as 

 the Bacillus mallei. In studying the writings of the older authors on 

 glanders, and the works of those authors who contested the contagious 

 nature of the disease, 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 

 will inevitably produce the disease, we find a vast difference in the 

 contagious activity of different cases of glanders. We find a great 

 variation in the manner and rapidity of the development of the dis- 

 ease in different individuals and that the contagion is much more apt 

 to be carried to sound animals under certain circumstances than it is 

 under others. Only certain species of animals are susceptible of 

 contracting the disease, and while some of these contract it as a gen- 

 eral 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 

 inoculated with the disease, while the discharge from chronic semi- 

 latent 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 neigh- 

 borhood 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 glan- 

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

 work in the same wagon, or are fed from feed boxes or mangers 



