1922.] 231 



LIVE STOCK. 



THE IMPORTANCE OF THE TUBERCULIN TEST. 



By Captain H. V. M. Metivier, o.b.b, b.sc, m.r.c.v.s., 

 Government Veterinary Surgeon. 



Bovine Tuberculosis is up to the present an incurable disease and 

 no means is known of giving protection to cattle by vaccination or 

 otherwise. At one time it was advocated that protection could be 

 afforded cattle by inoculating tubercle bacilli of the human type into 

 calves, and thus producing immunity against the bovine type, but it was 

 subsequently discovered that animals thus treated, although immune to 

 the bovine disease continued to give milk (in the case of cows) rich in 

 human tubercle bacilli and consequently such a method of vaccination 

 was abandoned. 



Although the progress of the disease is as a rule slow, nevertheless 

 an infected animal may, after the lapse of a few years, cause the 

 infection ef an entire herd and it is to the advantage of every owner to 

 test his animals periodically to make sure that his cattle are free from 

 tuberculosis. 



Tuberculosis is no doubt a disease of domestication. Animals that 

 are confined in pens suffer much more from the disease than those that 

 lead an open air existence : for instance tuberculosis is to all intents and 

 purposes unknown in sheep in the United Kingdom. In the same way 

 the disease in the United Kingdom is more frequently found in milch 

 cows which are confined to shippons and byres than in beef cattle which, 

 before they are eventually slaughtered, spend most of their life in the 

 open air. For these reasons it is pointed out that tuberculosis is less 

 common in cattle in the tropics than in a temperate climate, because our 

 are less confined to sheds, byres and shippons than in colder regions. 



In spite of this however it would be to the advantage of both owners 

 of cattle and the consumers of milk in the Colony that animals should be 

 tested from time to time so as to detect at once any animal infected with 

 the disease. The best method of testing cattle is by the Tuberculin 

 Test, the hypodermic test being the one usually employed. 



Tuberculin is an extract of dead tubercle bacilli in broth, to which a 

 very small quantity of Carbolic acid is added to ensure its keeping It 

 is made by growing at body temperature tubercle bacilli in flasks 

 containing broth and after an abundant growth is obtained the flasks are 

 subjected to a great heat which destroys all the organisms. The 

 contents of the flasks are then filtered and the clear filtrate is tuberculin, 

 As already pointed out a small quantity of Carbolic acid is added to this 

 clear liquid. 



Summary of the Subcutaneous Test. 



(1) Dose 3c. c. for a cow, 4c.c. for a bull. 



(2) The animals temperature must be taken at least once the day 



before testing and also at the time of testing. The test is only 

 reliable in those whose temperature is not above i08<^ F. at 

 the time of injection. 



