328 CONTAGIOUS DISEASES. 



some other, perhaps trivial, cause ; the ilhiess continuing longer 

 than usual, and the animal, being fat, is slaughtered to prevent 

 loss, and the ])ost mortem reveals the presence of tubercular 

 tumours in various parts of the economy. In this case some of 



■ the tumours will be found in a softened, semi-fluid condition, 

 the contents of which being absorbed, induce the continuance 

 or aggravation of the otherwise trivial illness. Generalised 

 tuberculosis only occurs when the blood-stream has become in- 

 fected by the entrance of the bacilli. Nocard says : — " It often 

 happens that apparently healthy animals slaughtered for human 

 consumption are found to have several organs invaded by the 



■ disease, yet in such condition it cannot be said that the disease 

 is generalised : these are successive localisations, and it is main- 

 tained that general tuberculosis only occurs when all the glands 

 in the chain are destroyed, the lymph carries the bacilli into the 

 thoracic duct, whence they are poured into the anterior cava, or, 

 again, when a tubercular focus penetrates a vein of a certain size 

 and pours into it the virulent material which it contains. Tuber- 

 culosis then assumes the character of a general disease, and all 

 the vascular tissues are virulent, and the tissues which are 

 favourable to the growth of the bacilli, notably the liver and 

 spleen and the marrow of the bones, become the seat of a 

 number of specific granulations all of the same size and agej 

 which constitute what is known in human medicine as granular 

 or acute miliary tuberculosis." Miliary tubercle in the spleen 

 is said by Ostertag to be the surest sign of general tuberculosis. 

 Although the animal may be fairly fat, the flesh usually is pale, 

 watery, pitting under pressure, and prone to rapid decomposition. 



In deep milkers, and in some highly bred cattle, the cachexia 

 may seem to precede and accompany the tuberculosis, and gene- 

 rally the earliest signs are those of unthriftiness, and deteriora- 

 tion in the quality of the milk, which becomes thin and watery, 

 aUhough for some time it may keep up in quantity. If the cow 

 be in calf, abortion is apt to occur ; if not pregnant, the condition 

 called nymphomania is frequently present. The appetite is 

 capricious ; the mucous membranes pale ; a cough of a dull 

 character exists ; the skin looks dull, the hair dirty ; the animal 

 does not lick itself, and, in the white parts, the skin is often 

 observed to be yellow. Emaciation now proceeds more or less 

 rapidly; the cough becomes troublesome, but there is seldom 



