The double intradermic test in cattle / by T. Dalling, J.H. Mason and W.S. Gordon.

  • Dalling, Thomas.
Date:
1927?]
Catalogue details

Licence: In copyright

Credit: The double intradermic test in cattle / by T. Dalling, J.H. Mason and W.S. Gordon. Source: Wellcome Collection.

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    Reprinted from The Veterinary Journal, Vol. 83, No. 8, Pages 382-393. Ill t • THE DOUBLE INTRADERMIC TEST IN CATTLE. By T. DALLINCx, M.R.C.V.S., J. H. MASON, M.R.C.V.S. and W. S. GORDON, M.R.C.V.S., The Wellcome Physiological Research Laboratories, Beckenham, Kent. Our interest in the double intradermic tuberculin cattle test arose from a suggestion which had reached us that a given tuberculin, which on the official guinea pig test had been proved equal to the (Koch’s) Frankfort standard, might fail to give “ positive ” reactions in tuberculous cattle when used in the double intradermic test, while another sample similarly standardised gave definite reactions. (We may here anticipate our findings by stating that we found no evidence for the truth of the suggestion.) We soon found that we had to investigate many points before we could get a satisfactory answer to our question, so that our enquiry, instead of being merely an investi¬ gation of tuberculin, had to become an investigation of the consistency of conclusions drawn from the test. Owing to th$ broadminded attitude and friendly interest of several owners of dairy herds within reasonable distance of our laboratory, we were able to carry out intradermic work on a mixed dairy herd including milch cows, pregnant cows, heifers, calves and bulls. Our investigations were limited because we were not able to carry out many subcutaneous tests, nor were we able to kill cattle. The restrictions under which we worked must be borne in mind when reading this report. We carried out in all between 400 and 500 tests on 150 animals, mostly cows and heifers. We have reason to believe that the tuberculin we used in most of this work has proved itself a satisfactory tuberculin for the detection of tuberculosis in cattle. We are in general agreement with the Tuberculin Committee that the double intradermic test is a convenient one under certain circumstances, and has “ come to stay.” It is, therefore, of con¬ siderable importance to the veterinary research worker and to the veterinary surgeon, acting for the dairy farmer, to define as closely as possible the limitations of the test and its degree of accuracy. We set out with the idea that we had simply to find some dozen “ positive reactors ” to the test and acquire these as a laboratory test herd of tuberculous animals for repeated experiments in the comparison of various experimental tuberculins in which we were interested. Our early tests, however, indicated that a cow giving a “ strong positive ” reaction might, a UPfeiight later, fail to show the same degree of reaction to the same tuberculin. We had, therefore.