DISEASES OF CATTLE 281 



age normal, the animal is generally regarded as having given a pos- 

 itive reaction. 



Usually the rise in temperature of a tubercular animal is much 

 greater 4 to 6 degrees F. and there is no question as to the result. 

 When the rise is close to 2 degrees F. and the temperature not above 

 104 at any time, the reaction is classed as doubtful. In all cases, 

 and especially in the doubtful ones, the interpretation of the record 

 should be made by an experienced person, who should be furnished 

 with all the information possible, concerning the condition of the 

 animals, the age, whether raised or purchased, whether from a 

 healthy or diseased herd, the number of reacting animals in the 

 herd tested, whether tested previously or not, etc. 



The positive, tuberculin reaction generally shows a regular 

 rise, the temperature remaining at the highest point for only a short 

 time, then falling gradually to the normal. The decline is usually 

 more rapid than the rise, although exceptions are noted. The 

 character of the curve should also be taken into consideration. A 

 widely fluctuating temperature, say a high, then low and later a 

 high temperature, is not a characteristic curve and should be classed 

 as doubtful rather than as a positive reaction. 



Are Any Other Changes to Be Noted in a Reacting Animal 

 Other Than the Rise in Temperature? Some of the reacting ani- 

 mals show the effects of the tuberculin by shivering, staring coat, 

 refusal to eat, etc. In some cases these symptoms are very notice- 

 able, in others they do not appear at all. In the case of nonreacting 

 animals, no such symptoms are ever noted. There is also frequently 

 to be noted at the point of injection, a slight swelling in the case 

 of reacting animals, but usually this is so slight that it is not no- 

 ticeable. 



Are There Other Ways of Testing Cattle for Tuberculosis Other 

 Than by the Detection of a Fever After Subcutaneous Inoculation? 

 A number of. other tests have been tried, but none have been 

 found nearly so reliable as the subcutaneous, the method above de- 

 scribed. Tuberculin especially prepared, has 'been placed in the 

 eye, or rubbed on a small area of the skin after it has been scratched, 

 or injected into, not beneath, the skin. In the case of many tu 

 berculous animals, a more or less marked inflammation of the eye 

 or skin at the point of application results. 



What Should Be Done With the Animals That Give Doubtful 

 Reactions? They should be retested, but this should not be done 

 for at least 60 days, as a tuberculous animal will not react to a 

 second dose of tuberculin injected soon after the first. Time must 

 be given for the original tuberculin to be eliminated from the sys- 

 tem. When retested, a triple dose should be given. 



Is the Test Always Correct? Not absolutely so, for a number 

 of reasons. When applied with judgment and care, it is correct in 

 at least 95 per cent of the cases. 



To What Are Errors Due? If cattle are tested that come in 

 the classes mentioned as those that should not be tested, a fever 

 may be noted that is not the result of the tuberculin, or if the cat- 



