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 healthy animals was killed and on examination found to be tubercular. This again has caused a certain distrust of the tuberculin test. Again, cattle have been removed from herds on account of having reacted to the tuberculin test, and on slaughter the lesions of the disease have not been found in their bodies. These things indicate that the tuberculin test has certain limitations which should be recognized by everyone who is using the test. If these limitations are recognized, I feel very certain that all will be better satisfied than when the test is considered to have no limitations. Tuberculin is an extract of a specific pathogenic organism, the tuber- cle bacillus. In tuberculin are contained certain specific products which when injected into the body of a tubercular animal produce certain disturbances. One of these disturbances is a thermal one, the tuberculin causing more or less of a temporary fever, and, since the temperature of an animal is a thing that can be easily measured, this thermal reaction is what is used to detect whether the tuberculin has had a disturbing effect upon the body of the animal or not. A very curious phenomenon has been noted within the last few years. It has been found that if an animal, such as a guinea pig, is injected with a very small amount (one-fifth of a drop) of blood serum from a different kind of animal, for example, a horse, and about ten days later the same guinea pig is given a larger dose (about 5cc.) serious disturbances follow within a few moments. The quantity of blood serum first injected produced absolutely no harmful effect. It has, however, sensitized the guinea pig, as it is called, and when the larger amount of blood serum is injected, which in the case of a guinea pig that had not received the small sensitizing dose would be without effect, it produces serious illness, often terminating in death -within a few moments. It is believed that the reaction of tuberculin + is allied to this phenomenon. The animal is sensitized to the products of the tuberculin bacillus by the growth of the organism within the body. When these specific products are introduced, they produce more or less of an effect. If a series of guinea pigs is injected with blood serum and after a definite time the animals are again injected with a larger dose, certain differences will be noted. One animal may die within a short time, another may show signs of serious illness but may recover, while another will show that the second dose has had a much smaller effect upon it. The same thing is true in the case of the injection of tuberculin into tubercular animals. The extent of the thermal reaction in tubercular animals may vary from 0° to 6- or 7° F. The normal temperature of cattle varies widely, not only between different animals, but in the same animal, from day to day and hour to 98
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