Tuberculosis. 461 



tuberculin, though s. post mortem proved the presence of tubercu- 

 losis. Unscrupulous men, wishing to sell on a guarantee, can 

 avail of this in animals so unaffected by the test. 



15. The operator must have absolute control, even of the feed- 

 ing and watering of the animals on the day of testing. Other- 

 wise the rise of temperature may be prevented by a liberal use of 

 antipyretics and a false guarantee may be secured. 



16. An unthrifty animal, having general symptoms suggesting 

 tuberculosis, must be subjected to the most critical examination 

 in addition to the tuberculin which in such animals often fails to 

 cause hyperthermia. Fortunately in such animals the tubercles 

 are usually numerous and extensive enough to be discovered 

 through objective symptoms. 



17. Animals excluded from the te.st by reason of some individ- 

 ual unfitness at the time (parturition, oestrum, abortion or any 

 other disease) must be marked and held for the test later after 

 such disqualification shall have pas.sed. 



18. The operator must bear in mind the possibility of trans- 

 ferring other diseases from animal to animal, by contact, by the 

 use of the same hypodermic needle on two in succession, and 

 above all by the clinical thermometer. Diseases like contagious 

 abortion, which present no obvious symptoms in the intervals, 

 are especially liable to be carried in this way, and instances of 

 the active extension of this after a test, have come under my 

 notice. The operator .should always enquire carefully as to the 

 existence of abortions and sterility in the herd, put the aborting 

 animals by themselves, using a special thermometer upon them, 

 and carefully washing the hands before going to other cattle. It 

 is well further to clean the thermometer after each animal and 

 ■disinfect it with carbolic acid solution (5:100). 



Dose of Tuberculin. Of the usual American preparation 2cc. 

 (30 drops) is adapted to a cow or ox of 1,000 to 1,200 pounds. 

 For larger and smaller animals a moderate encrease or reduction 

 must be made, yet a considerable latitude is allowable. The 

 new-born calf will take five drops and the animal of 700 pounds 

 25 drops. 



Technique of the Operation. I^apses are so easily made when 

 dealing with a large herd and are- so dangerous that a regular 

 plan should be systematically followed. The following will be 

 found simple and convenient : 



