DISEASES OF CATTLE. 407 



TUBERCULOSIS. 



[Pis. XXXI V-XXXV III.] 



Tuberculosis is an infectious and communicable disease charac- 

 terized in its early stages by the formation, in various organs of the 

 body, of minute nodules or tubercles, which contain Mycohactenwm 

 tuberculosis, the cause of the disease. 



The disease, in its various manifestations, has been known for 

 many centuries, and legislative enactments having reference to the 

 destruction of affected animals and forbidding the use of the flesh 

 date far back into the Middle Ages. The opinions entertained re- 

 garding the nature and the cause of the malady varied much in dif- 

 ferent periods and very markedly influenced the laws and regula- 

 tions in vogue. Thus, in the sixteenth century, the disease was con- 

 sidered identical with syphilis in man. In consequence of this belief 

 very stringent laws were enacted, which made the destruction of 

 tuberculous cattle compulsory. In the eighteenth century this 

 erroneous conception of the nature of the disease was abandoned 

 and all restrictions against the use of meat were removed. Since 

 that time, however, its communicable nature has been established by 

 many investigators, and the tide of opinion has again turned in 

 favor of repressing the disease and prohibiting the sale of con- 

 taminated products. 



Oocurrence. — The statistics concerning tuberculosis show that it is 

 a disease prevalent in all civilized countries. In some countries, such 

 as the northern part of Norway and Sweden, on the steppes of east- 

 ern Europe and Kussia, in Sicily and Iceland, and in Algiers, it is 

 said to be quite rare. 



The returns from testing British cattle with tuberculin, supplied 

 by the Koyal Veterinary College, as stated in March, 1900, showed 

 that among 15,392 animals tested 4,105, or 26 per cent, reacted. 



During the slaughter of cattle for pleuropneumonia careful exami- 

 nations of the carcasses were made for tuberculosis. Of 300 head 

 killed near Edinburgh 120, or 40 per cent, were tuberculous. Of 

 4,160 killed in England 20 per cent were tuberculous. Of one of 

 these lots of cattle (451 animals) the president of the Lai::cashire 

 Farmers' Association testified that they were fairly representative 

 cattle — cows, heifers, and growing stock — a thoroughly mixed lot; 

 20 per cent of them had tuberculosis. 



Of 398 bovine animals taken haphazard in the city of Manchester, 

 120, or 30 per cent, were tuberculous. Among them were 168 cows, 

 69, or 41 per cent, being tuberculous, and 2 having diseased udders. 



The result of testing the Queen's herd at Windsor was that 36 out 

 of 40, or 90 per cent, were found tuberculous. 



