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 Data along this line have been published by Dr. V. A. Moore of the Cornell Veterinary School. Those obtained from the study of a herd of cattle are given In Table 111. A herd of 491 animals was tested and 96 did not react to the test. These non-reacting animals were removed and placed in quarters where there was no opportunity for Infection to occur. Retests were made at intervals of six months with the results as shown. It will be seen that at each test one or more animals were found to be diseased, so that by the end of four years but 19 out of the original 96 had not reacted to the test. Possibly In certain cases the reactions were caused by reinfection from other animals in which the disease had progressed from the dormant stage to an open type between the successive tests. It is certain that a large part of the reactions obtained on the retests were due to the fact that at the time the previous tests were made the disease was in a dormant stage. Additional data might be presented along similar lines. Such facts as these have led the live stock sanitarians to believe that the healthy herd, not the healthy individual animal, must be taken as the unit in fighting the spread of tuberculosis. This is emphasized in the report which was made last year by the commission appointed by the American Veterinary Association to study the subject of bovine tuberculosis, when they recommended that in the case of herds in which over 50% of the animals were found diseased on the first test the whole herd should be considered as diseased; that In the case of such herds it Is not worth while to attempt to breed a healthy herd from this foundation by separating the herd into two parts-the re- acting and the non-reacting animals-because a considerable portion of the non-reacting animals have the disease either in the incubation period or in a dormant form. In a herd of any size in which the disease has been present for any length of time, such animals are to be found, and their presence can only be detected by making frequent tests on the herd. When the breeders realize the importance of this point in the spread of bovine tuberculosis, we shall not have a spectacle presented to us of a dispersion sale of a herd of pure bred animals in which shortly before the sale the tuberculin test showed 20% of the animals to be in- fected. It seems to those best fitted to judge that if one wishes to be ab- solutely certain of purchasing a healthy animal he must buy his an- imals from herds that are known to be free from tuberculosis; that If he buys, even on the tuberculin test, from an infected herd he runs the chance of purchasing a diseased animal. In the case of herds that are not extensively diseased, In which but one or two reacting animals have 102
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