12. Cattle just from a long journey by road or rail, or other cause of violent exertion are liable to have an elevated temperature from the leucomain poisoning. Such should be left at rest until the transient fever shall have subsided.
13. Violent handling of nervous cows in taking the temperature must be carefully avoided. The operator who cannot handle them gently is not fit for this work.
14. There must be evidence that the animals have not been repeatedly tested at short intervals shortly before. In a number of instances I have found a proportion of the cattle irresponsive to tuberculin, though a post mortem proved the presence of tuberculosis. 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 feeding and watering of the animals on the day of testing. Otherwise 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 test by reason of some individual unfitness at the time (parturition, œstrum, abortion or any other disease) must be marked and held for the test later after such disqualification shall have passed.
18. The operator must bear in mind the possibility of transferring 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. Lapses 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:
1. Inject the herd at 10 or 11 P. M. to secure a good rest and be fresh for the rise of temperature early next morning.