24: 



LIMITATIONS OF THE TEST. 



The test should not be applied to cows that have just calved or are about 

 to calve, as the temperature at this time is apt to vary considerably from the 

 normal. For the same reason it should not be applied to any animal that is 

 in a feverish condition from any cause. 



The test fails to detect the presence of the disease in the animal that is 

 very recently infected. The disease has to make a little progress before the 

 test reveals its presence, and in the beginning of each case there is a period 

 between the entrance of the germs into the body and the time when they have 

 multiplied sufficiently for the test to reveal their presence. This is called the 

 period of incubation and lasts from ten days to two months. 



When the disease is far advanced and the animal is wasting, the test some- 

 times fails to detect it. This is not of much practical importance as such eases 

 can generally be recognized without the aid of tuberculin. 



PROTECTIVE INOCULATION. 



For some years efforts have been made to discover a method of rendering 

 cattle immune to the disease in such a way as men are protected from smallpox 

 by vaccination. Up to the present these efforts have been only partially success- 

 ful, and until the methods in use have been perfected by further investigations, 

 they cannot be recommended as of practical use in the suppression of the 

 disease. 



SUPPRESSION OE THE DISEASE. 



The first step in getting rid of the disease is to find out how many of the 

 herd are affected by it. This is done by applying the tuberculin test. This 

 will show a larger or smaller number of the herd to be affected, and the proper 

 course to pursue will depend largely upon the proportion of the reactors in it. 



Suppose that only a few cattle react, say fifteen out of a hundred, or in 

 that proportion. In this case the reactors are first carefully examined and 

 if any of them show symptoms of the disease by coughing, loss of condition 

 or any other of the signs by which the disease is recognized without the test, 

 such animals should be slaughtered. 



The other reactors should then be entirely separated from the healthy 

 cattle. If possible they should be put in a separate building, but if this cannot 

 bo done, a tight partition should be built between the diseased and the healthy 

 cattle, and separate ventilation provided. The person who attends to the 

 reactors should not go near the healthy animals, as he may carry the infection 

 to them on his hands, clothes or boots. For the same reason, the feeding and 

 watering must be done with separate utensils. 



When at pasture, the reactors must not be put into a field where they can 

 reach across a fence to healthy cattle. Whenever a calf is born among the 

 reactors, it should be immediately separated from its mother and brought up 

 by hand or on a healthy cow. The calf is usually born healthy, but would 

 soon catch the disease from its mother if allowed to remain with her. 



