HORSE-POX. 497 



fact of these tumours entering into and destroying the tissues in 

 which they are located, the affected animal wastes away and dies. 

 In advanced cases, there is generally very profuse urination. It 

 appears to be in the horse, as in man, a very fatal disease, for 

 which there is no cure. In human beings it is known as con- 

 sumption. It is a comparatively rare disease in horses. 



In the large majority of cases of tuberculosis in the horse, the in- 

 fection appears to have been brought in cows' milk, with which 

 the affected animals have been fed. Hence, as a great rule, this 

 disease attacks only young horses. Tuberculosis is very common 

 among horned cattle. If horses, and especially young ones, be fed 

 either wholly or in part on cows' milk, the precaution of heating 

 it to at least 175° F. should be observed, so as to destroy any 

 bacilli of tuberculosis which may be in it. This pasteurization of 

 milk can best be effected by a special apparatus which costs from 

 £20 to £30. 



Except when artificially cultivated, the tubercle microbe does not multiply 

 outside the animal body; and although it will live for some time (say, up 

 to a year under very favourable conditions) apart from its " host," it is 

 essentially an animal resident. In the horse, these germs gain entrance 

 into the system generally with the food or drink, and make the alimentary 

 canal their first point of attack. They are then carried in the blood-stream 

 to various internal organs — such as the lungs, liver, spleen and brain — 

 where the inflammation to which their presence gives rise, causes the 

 formation of tubercles, which present two different appearances, though of 

 the same nature, namely, small nodules (miliary tubercles) and diffuse 

 tumours. Although they generally keep between the limit of size of a 

 pin's head to that of a greengage, they may be as big as an ostrich's egg, 

 or even larger. The tissue, with its small blood-vessels, becomes destroyed 

 at the seat of the formation of a tubercle, so that this new growth, being 

 unprovided with blood, dies, breaks up into soft cheese-like material, and 

 finally it is converted into earthy matter, or into a small fibrous nodule. 

 In this manner, these microbes gradually destroy the tissue which they 

 invade, and give rise to general decay, and special symptoms, according to 

 their point of attack. For instance, the presence of tubercles in the brain 

 will, as a rule, be followed by signs of mental disturbance. The tumours 

 which are found, not very uncommonly, in the spleen and brain of horses, 

 are in the large majority of cases, of tuberculous origin. In a horse infected 

 with tuberculosis, there is an increasing weakness, loss of condition, pale- 

 ness of the mucous membranes, ajid an excessive flow of watery urine. 

 Post-mcrrtem examination shows that the spleen and glands of the mesentery 

 are considerably enlarged. Wit]>out- a microscopical examination, it is 

 impossible to decide the question whether or not a horse has died from 

 tuberculosis. McFadyean has demonstrated that the tumours in the spleen, 

 which were formerly ascribed to lymphadenoma, are those of tuberculosis. 



Horse-Pox (Variola Equina). 



This is a rare disease which appears to be identical with the cow- 

 pox of cattle. Its effects are mild, and in themselves, entirely free 

 from danger to the life of the animal. Unlike the small-pox of 



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