Tuberculosis. 



123 



Tuberculosis of bones and joints. —"^^aS.^ is especially seen in 

 young growing animals, being common in calves in badly infected 

 herds. Wm. Mueller has produced it experimentally by inject- 

 ing the nutrient artery of the bone in a three month's goat. The 

 bones most commonly attacked are those entering into the for- 

 mation of the elbow and knee, the stifle and hock, and as the dis- 

 ease usually extends from the gristly growing substance in the 

 bones of the joint surface, the trouble is recognized as disease of 

 the joints. In some instances, however, the disease begins in the 

 lining membrane (synovial) of the joints and forms fungous 

 growths extending into the bone. In the open (cancellated) tissue 

 on the end of the bone it is at first red and congested, later it is 

 partly fatty, and caseated. Usually the disease becomes general, 

 but if it remains circumscribed, it is enveloped in a layer of dense 

 hard bone. The animal is very lame, perhaps even unable to rise, 

 the joints swollen and tense, and the ends of the bones enlarged 

 and tender. The disintregrated bone may even crumble and the 

 sharp spiculae protrude through the skin. 



Further hidicaiions of Tuberculosis. 



The above outline of symptoms seen in cattle is rendered neces- 

 sary by the invariable question, " how can I recognize it?" The 

 intelligent reader will realize from the partial sketch above, that 

 it is no simple matter to diagnose tuberculosis. It is to be hoped 

 that he will also have apprehended so much of the subject as will 

 save him from being victimized, by the man who boasts loudly, 

 but really knows little. 



In the multitude of equivocal and occult cases further tests 

 must be applied. These may be named as (i) microscopic search 

 for the bacillus, (2) inoculation, and (3) "injection of tuberculin. 



Inoculation. — The first named test having been already inci- 

 dentally referred to, inoculation may be noticed. This consists in 

 the introduction into the peritoneum or other part, of a guinea- 

 pig or other animal or some of the suspected product (discharge 

 from the nose, milk, juice from an enlarged gland, etc.) General 

 abdominal tuberculosis should be present in the guineapig in 30 

 days. Beside the delay, this has the draw-backs, that the guinea- 

 pig may have been already infected before the inoculation, the 

 portion of the suspected product may have been devoid of bacilli 



