191 1.] The Control of Tuberculosis in Cattle. 231 



be properly pasteurised unless from cows known to be free 

 from tuberculosis. 



None of the methods for the immunisation of animals 

 against tuberculosis are recognised as having passed 

 sufficiently beyond the experimental stage. 



Diagnosis of the Disease. — With regard to the tuberculin 

 test the Commission are of opinion that tuberculin, properly 

 used, is an accurate and reliable agent for the diagnosis of 

 active tuberculosis. Tuberculin may not, however, produce 

 a reaction when the disease is in a period of incubation, when 

 the progress of the disease is arrested, or when the disease is 

 extensively generalised. In this last case, detection is usually 

 possible by physical examination, while in the two former 

 cases the disease may sooner or later become active, so that 

 animals which have been exposed to infection should be re- 

 tested with tuberculin every six months. The tuberculin test 

 should not be applied to any animal having a temperature 

 higher than normal. The subcutaneous injection is the only 

 method of making the tuberculin test that is recommended by 

 the Commission ; bift when an animal has given a positive 

 reaction in any properly conducted test, it should thereafter 

 be regarded as tuberculous, and such reaction should be 

 considered sufficient evidence upon which to declare the herd 

 infected. 



The Commission recognises that the discovery of tuber- 

 culosis in animals slaughtered for food purposes furnishes one 

 of the best possible means of locating the disease on the farm, 

 and some system of marking should therefore be adopted for 

 purposes of identification. 



Method Recommended. — As a general policy in the eradica- 

 tion of tuberculosis, the separation of healthy and diseased 

 animals, and the formation of healthy herds are recommended. 

 If a herd is found to be extensively infected (i.e., 50 per cent, 

 or more of diseased animals), even the apparently healthy 

 animals should be regarded with suspicion until they have 

 been separate from the reacting animals for at least three 

 months. Such a herd should not be treated by the method 

 of general separation. The formation of a new herd from the 

 offspring only is advisable. 



In the case of herds containing less than 15 per cent, of 



