398 DISEASES OF CATTLE. 



TUBERCULOSIS. 

 (Plates XXIX, fig. 6; XXXIV to XL, inclusive.) 



Tuberculosis is an infectious and communicable disease charac- 

 terized by the formation in various organs of the body of minute 

 nodules, or tubercles, which contain the BaciUus 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 destruc- 

 tion of affected animals and forbidding the use of the flesh date far back 

 into the middle ages. The opinions entertained regarding the nature 

 and the cause of the malady varied much in different periods, and very 

 markedly influenced the laws and regulations in vogue. Thus, in the 

 sixteenth century, the disease was considered 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 dis- 

 ease was abandoned and all restrictions against the use of meat were 

 removed. Since that time, however, the communicable nature of this 

 disease has been established by many investigators, and the tide of 

 opinion has again turned in favor of repressing the disease and pro- 

 hibiting the sale of contaminated products. 



Occurrence. — 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 eastern 

 Europe and Russia, 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 Royal 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 pleuro-pneumonia 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 Lancashire 

 Farmers' Association testified that they were fairly representative 

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

 20 per cent of these animals had tuberculosis. 



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

 120, or 30 per cent, were tuberculous. Among these animals were 1 68 

 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 

 40, or 90 per cent, were found tuberculous. 



The investigations made by the British Dairy Farmers' Association 

 deserve particular attention, coming as they do directly from a cattle 



