INFECTIOUS DISEASES OF CATTLE. 407 



in the blood and lymph, and can they be detected in the muscular 



(1) Disease of the bones is not unknown, although very rare. Accord- 

 ing to Walley it appears chiefly in the spongy bones of the head and 

 backbone and in the long bones of the limbs. Occasionally the ends of 

 the bones, where they are covered by the synovial membrane of the 

 joints, are dotted with tubercles. The muscular system itself is very 

 rarely the seat of tubercular deposits, although the lymphatic glands 

 lying near and among the muscles may be not infrequently diseased. 



(2) Whether tubercle bacilli are found in muscle juice independent 

 of any tubercular deposits is a question which must be approached 

 experimentally. There is on record a great variety of opinions on this 

 matter, some authorities considering all flesh from tuberculous animals 

 unfit for food, while others hold a contrary view. Experiments have 

 shown that in rare cases the flesh of tuberculous cattle contains a small 

 number of tubercle bacilli. In Germany the flesh of animals in which 

 the disease is just beginning, or in which it is restricted to one or more 

 related organs, is not rejected. When, however, the disease has 

 aft'ected the muscles, or bones, or lymphatic glands situated on or 

 between them, the flesh is condemned as unfit and dangerous. Animals 

 are also rejected in which it is evident, from the general distribution of 

 tubercles throughout the various organs, that the bacilli have beeu 

 distributed by the blood and may have been carried into the muscular 

 system (generalized tuberculosis). 



Concerning the infections nature of milk secreted by tuberculous 

 . authorities have universally agreed that when the udder itself is 

 in the slightest degree involved the milk possesses infectious propcr- 

 and is therefore dangerous. Tubercle bacilli have been found in 

 large numbers, in the milk and the udder under such circtimsta: 

 I'nlike other affections of the udder, tuberculosis of this organ does not 

 at once change the appearance and the quality of the milk secreted. 

 Bang states that for at least a month after the disease has appeared the 

 milk is normal in appearance and may be consumed and sold without 

 arousing the suspicion of the owner. There is, therefore, considerable 

 danger involved in this disease, and the necessity for the careful \i\> 

 tion of dairy cows seems more urgent than ever before. 



Authorities are, however, not fully agreed as to whether the milk 

 from tuberculous cows in which the udder is apparently not invaded 

 liy the disease should be considered dangerous or not. Some are in- 

 clined to believe that the milk secreted by healthy udders is never 

 infeetious even when the lungs or other organs are affected; that, 

 in oilier words, the tubercle bacilli are rarely, if ever, separated from 

 the lesions which they produce, and that the udder itself must be dis- 

 eased before tubercle bacilli can apj>ear in the milk. Experiment* 

 made tvith the milk of tuberculous cows in which there were no indica- 

 of udder disease do not bear out this theory, since tubercle bacilli 

 have been found in the milk of such cows. Some authorities, among 



