i8 Bulletin 150. 



demand from residents of this state for tuberculin the more unre- 

 munerated labor is heaped upon us. 



The value of the agent consists in this, that the hypodermic 

 injection of an appropriate dose in a tuberculous animal, however 

 lightly affected, produces in the course of the succeeding twenty- 

 four hours a rise of body temperature and other indications of 

 fever. The gradual rise and fall of the temperature in the ab- 

 sence of any other diseased or ph3'siological condition which 

 would bring this about is the most reliable of all symptoms of the 

 presence of the disease. Upon the sound animal S3'stem such 

 a dose of tuberculin produces no appreciable effect. 



It is important, however, that I should not be misunderstood 

 in this matter. The man who will use tuberculin without due 

 caution and without due consideration as to the condition and 

 environment of the animal, and who blindly condemns on any 

 rise of temperature will almost certainly condemn non -tubercu- 

 lous animals and bring the tuberculin test into discredit. The 

 intelligent use of the test, demands an intimate knowledge of the 

 kind of animals tested, both in the health}' and diseased condi- 

 tion, and a careful scrutin}^ before and during the test. 



I St. The subject must 'be ifi good general health. If there is 

 present in the sj'stem an}- concurrent disease it may undergo an 

 aggravation within twenty-four hours and give a rise of temper- 

 ature that will be mistakenly set down for tuberculosis. At the 

 very start, therefore, it is important that the general health of 

 the subject should be first assured by a critical professional ex- 

 amination. If some other disease is present the tuberculin test 

 had best, as a rule, be delayed until that has subsided, while if 

 tuberculosis is found the test will be superfluous. 



2d. The subject must not be within three weeks of parturitio7i , nor 

 abnU to abort. In man}' cases, though not in all, as preparations 

 are made for calving, the system becomes unduly susceptible to 

 the presence of tuberculin and that agent will cause a rise of 

 temperature, though no tuberculosis is present. Unless this 

 source of error is carefully guarded against the most valuable 

 cows in the herd may be condemned unjustly. 



3d. The cow must 7iot be within three days of the period at which 

 " heat " would naturally occur. Under the excitement of oestrum 



