No. 7. DEPARTMENT OF AGRICULTURE. 697 



likely to aijpear in young animals than in adults, and is more com- 

 mon among swine than among cattle. 



Tuberculin was invented by Koch in 1890, and was first used ex- 

 perimentally as a remedy for tuberculosis. It was observed that 

 whenever tuberculin was administered to a consumptive or tuber- 

 cular patient the administration was followed by a fever, called a 

 reaction, lasting a few hours or a day. This observation led veteri- 

 narians to apply tuberculin to tubercular and suspected cattle for the 

 purpose of determining whether a similar fever or reaction would 

 occur. It was soon found that a small quantity of tuberculin injected 

 beneath the skin of a tubercular cow would, with remarkable regu- 

 larity, cause a febrile reaction, whereas, no change w^as produced in 

 animals that w^ere not afflicted with tuberculosis or were suffering 

 with some other disease. Since 1891, the use of tuberculin for test- 

 ing cattle to determine the presence of tuberculosis has grown at a 

 rapid rate in all parts of the world. It has not been found, and has 

 never been claimed that tuberculin is an infallible diagnostic agent. 

 It has, however, been shown conclusively that tuberculin has in- 

 creased the power to recognize tuberculosis many fold and furnishes 

 results that are immeasurably more accurate than those obtained by 

 the use of any other agent or method than has ever been employed 

 or proposed. 



During the period of operation of the State Livestock Sanitary 

 Board, 44,801 cattle have been examined and tested with tuberculin 

 at the expense of the State, and of these, 5,860 have been condemned, 

 destroyed and paid for. The payments have averaged about |23.00 

 per head. An attempt has always been made to select the most ex- 

 tensively diseased herds for inspection. During the first eighteen 

 months of the work, that is up to June 14, 1897, 9,108 cattle were 

 tested, and of these 1,839 were condemned. The percentage of 

 tuberculosis, therefore, was 20.39. From June 14, 1897 to June 14, 

 1899, 16,G87 cattle were examined and 2,116 were condemned making 

 the percentage of tuberculosis 12.67. The fact should not be lost 

 sight of in this connection that these figures represent the percentage 

 of infection among the most extensively infected herds in Pennsyl- 

 vania. Since June, 1899, very few herds have been examined where 

 there was not the strongest reason to believe that they were infected, 

 and indeed extensively infected, before the inspection was made. 

 At present, a good many herds are being examined at the expense of 

 their owners and the tubercular animals taken over by the State. At 

 least as many herds have been examined by their owners as have 

 been examined by the State, and only a limited portion of the tuber- 

 cular cattle found in these herds are appraised and paid for by the 

 State. Some of them are no doubt sold to drovers and disposed of to 

 other farmers where they may have an opportunity to spread dis- 

 ease and others are sold to butchers and turned into food for man. 

 Still others are destroyed by their owners and no compensation is 

 asked for. It should not be inferred that in these inspections made 

 at private expense anything like as many tubercular cattle are found 

 as in inspections made by the State, because the inspections made 

 privately frequently, if not usually reveal nearly the entire herd to 

 be free from infection. 



The applications for herd tests are from three to four times as 

 numerous as the inspections made by the State. Some applications 



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