Wisconsin Dairymen's Association / Fortieth annual report of the Wisconsin Dairymen's Association : held at Beloit, Wis., November, 1911. Report of the proceedings, annual address of the president, and interesting essays and discussions relating to the dairy interests
Hastings, E. G.
Tuberculin and its uses, pp. 97-106 PDF (2.1 MB)
Fortieth Annual Report of the A prominent eastern veterinarian in the handling of a large herd, which it was desired to put on a healthy basis, has removed every ani- mal that showed temperatures in excess of 102.8° after the injection of tuberculin; 40% of whose maximum temperature fell between 102.8' and 103.50 have shown lesions of tuberculosis on slaughter. It In easy to see that if 1040 had been the standard which had been adopted as indicating tuberculosis that a considerable number of diseased ani- mals would have been left in this herd. In Holland statistics have been gathered concerning the accuracy of the tuberculin test in the case of varying amounts of thermal re- action. It has been shown that in the case of animals that showed a maximum temperature after injection of 105.8° and above, but two per cent showed no lesions of tuberculosis on slaughter; in the case of cattle showing a reaction between 104' and 105.8°, sixteen per cent showed no lesions; between 103' and 104,° thirty-eight per cent showed no lesions; in the case of the animals that had temperatures less than 103' after injection fifty-four per cent showed no lesions on slaughter. The trouble is due to the fact that the injection of tuber- culin causes no definite degree of thermal reaction in the case of a tubercular animal. The variation in the time at which the reaction fever appears also differs widely. It usually is to be noted within ten to sixteen hours after the injection of tuberculin, but sometimes it appears much later. The fever usually persists for a short period of time. In the case of some tubercular animals, the fever may persist for 36 to 40 hours. These things render more difficult the interpretation of temperature records, since, in the case of a persistent fever, it is often thought that the fever must be due to some other cause than the tuberculin. Another condition that complicates the testing of cattle for tuber- culosis, and a condition that overlaps to some extent the one that has already been mentioned, is that in certain stages of the disease cattle do not react to tuberculin. There is always a considerable per- iod between the time of infection and the period when the disease be- comes established in the animal. This is known as the period of In- cubation. It is believed that it may in certain cases be two months in length. During this period animals do not react to the tuberculin. As soon as infection occurs, a struggle ensues between the organism and the body of the animal and the protective agencies of the body of the animal are at once set to work. If the infection has not been too great, undoubtedly these often stop the spread of the disease before it has made any headway. Again, the disease may continue to con- stantly progress and may soon cause the death of the animal; or, after making a certain headway, the disease may go backward even to 100
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