510 GENERAL DISEASES. 



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 gi'eat 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 althougli 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 e^g, 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 vdth blood, dies, breaks up into soft 

 cheese-like material, and finally 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 increasing weakness, loss of condition, 

 paleness of the mucous membranes, and an excessive flow of watery urine. 

 Post-7norfe7n examination shows that the spleen and elands of the mesentery 

 are considerably enlarged. Without a microscopical examination, it is im- 

 possible to decide the question whether or not a horse has died from tuber- 

 culosis. McFadyean has demonstrated that the tumours in the spleen, which 

 were formerly ascribed to lymphadenoma, are those of tuberculosis. 



Dourine (Covering D/sease, Mai du Coif). 



I have compiled the majority of the following remarks on this 

 disease from Friedberp^er and Frohner's " Pathologie," and from 

 Cagny and Gobert's " Dictionnaire Veterinaire." 



DEFINITION. — Dourine is a specific disease which at first ap- 

 pears as an inflammation of the surface of the genital organs, and 

 which causes grave alterations in the nervous system of the 

 attacked animal. Under natural conditions, it is confined to the 

 horse, ass, and their hybrids ; althouofh it can be conveyed to 

 dogs and other animals. It n.ins either a chronic or acute course, 



