Issued August 31, 1916. 



U. S. DEPARTMENT OF AGRICULTURE3 



BUREAU OF ANIMAL INDUSTRY. 

 A. D. MELVIN, Chief of Bureau. 



SPECIAL REPORT 



DISEASES OF CATTLE. 



may be noted in many of the reacting ani- 

 mals. Focal reactions are not often noted 

 in cattle. 



Interpretation of a Tuberculin Reaction. 



Hutyra ami Marek state that in animals over 

 six months of age a rise of 2.7° F. over the 

 highest normal temperature constitutes a 

 positive reaction or a rise of 0.9° F. or more 

 above normal w^hen the temperature exceeds 

 104° F. Also in cases where the tempera- 

 ture is elevated 1.8° F. to 2.5° F. above nor- 

 mal, Or w^hen it exceeds 103.1° F. and is ac- 

 companied by symptoms of an organic (sys- 

 temic) reaction. 



Calves under six months of age must show 

 a temperature over 104.9° to indicate a posi- 

 tive reaction. 



A negative reaction is indicated when the 

 post injection temperature does not exceed 

 103.1° F. and is not more than 2.7° F. above 

 normal and no local or organic (systemic) 

 reaction is shown. A careful and systematic 

 clinical examination should also reveal no 

 evidence or suspicion of tuberculosis. 



According to these authors if the results 

 of temperature records and careful clinical 

 examinations are interpreted according to 

 the above principles they will be found to 

 agree with post mortem findings in about 

 98% of all cases. 



Nocard believes that a positive reaction is 

 indicated when the post injection tempera- 

 ture exceeds the pre-injection temperature 

 by 2.7° F. and that an increase of 1.5° F. 

 to 2.5° F. indicates suspicion only. Sus- 

 picious cases should be re-tested after one 

 month, using a double dose of tuberculin. 



The International Veterinary Congress 

 held at Budapest declared that cattle show- 



GH, KiCKMAN, LAW, 

 , PEARSON, 

 ;0WER. 



N, 1916. 



\jtKj \ n, is.i\ ivi rj iM J. rivij.>j xii.'^G OFFICE, 



1916. 



