Tuberculosis. 503 



1 . The temperature of the animal is best taken at intervals, or 

 at least, morning, noon and night, on the day preceding the in- 

 jection to see that the subject shows no habitual rise at any time 

 of the day. Yet in busy field work the one night temperature 

 taken just before injecting will rarely fail to give a satisfactory 

 normal as a standard for the animal. Any quotidian rise almost 

 invariably reaches its climax at night. 



2. The subject must be in good general health. If there is 

 present in the system any concurrent disease it may undergo an 

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

 ture 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. 



3. The subject must not be within three weeks of parturition, nor 

 about to abort. In many 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. 



4. The cow must not be within three days of the period at which 

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

 the body temperature usually rises two or three degrees, and if 

 tuberculin has been used this rise may be attributed to tubercu- 

 losis and a sound animal may be condemned. Nor is it always 

 enough that the animal is supposed to be pregnant. Abortions 

 sometimes take place unexpectedly and unknown to the owner. 

 If, therefore, a cow under the test and which is not well advanced 

 in pregnancy should show a rise of temperature it should be at 

 once ascertained" whether the animal is not in ' ' heat. ' ' If symp- 

 toms of " heat " are found she should be set aside along with any 

 calving cows to be tested again when such a source of error is no 

 longer present. 



5. The tested animal must not be exposed to a hot sun in a 

 closed area. In excess this will cause heat apoplexy, and the 

 fever heat which ushers this in, may easily be mistaken for the 

 indications of tuberculosis. 



