Tuberculosis in Live Stock. 
15 
THE TUBERCULIN TEST. 
Testing animals with tuberculin is the process of introducing 
tuberculin into the animal and interpreting results according to well- 
known standards. Tuberculin is a laboratory product prepared 
scientifically and, when of standard potency and in the hands of 
skillful persons, it is a reliable agent for detecting tuberculosis in 
animals. It contains no living tubercle bacilli but is a product of 
the growth of tubercle bacilli properly mixed with a substance on 
which it has grown and properly diluted and preserved. No harm 
can result to healthy animals from the proper application of tuber- 
culin even if doses many times greater than the regular ones are used. 
The use of tuberculin by untrained persons is to bo discouraged 
for the reason that in many cases its effect on tuberculous animals is 
unobserved and not understood by those unfamiliar with its action. 
Tuberculin, by its immunizing projierty, can cause tuberculous ani¬ 
mals to fail to respond to its application at another time; therefore 
it may be misused by unscrupulous persons. 
THE SUBCUTANEOUS TEST (UNDER THE SKIN). 
The most frequently used method of testing is the subcutaneous 
test, which consists in injecting the proper quantity of tuberculin 
underneath the skin into the subcutaneous tissue. If an animal is 
tuberculous, the action of the tuberculin causes a fever, which is 
indicated by a rise in temperature. This rise, under ordinary con¬ 
ditions, may occur any time between the eighth and twentieth hours 
after the tuberculin is injected, but hi some cases it is desirable to 
measure the temperature before the eighth hour and continue to 
the twenty-fourth hour or longer. 
The temperatures are measured at least 3 times in advance of the 
injection, at 2-hour intervals, to learn whether the animal is in proper 
condition to receive the test. The temperatures after injection are 
taken every 2 hours until the test is completed. The proper inter¬ 
pretation of the temperatures is made by the person applying the 
test, and a careful observance of any clinical changes is always impor¬ 
tant hi determining the result. It can not be set forth too strongly 
that the test including the two following methods, should be at¬ 
tempted only by those who are properly qualified to do the work. 
THE INTRADERMAL TEST (INTO THE SKIN). 
The intradermal test for detecting tuberculosis is used to a con¬ 
siderable extent, especially on range cattle not easily controlled. 
When made by those who have become skilled in its application, 
it is very accurate. In this test the tuberculin is injected between 
the layers of the skin, only a few drops being used, and it is usually 
