Issued August 31, 1916. 



U. S. DEPARTMENT OF AGRICULTURE^ 



BUREAU OF ANI>AAL INDUSTRY. 

 A. D. MELVIN, Chief of Bureau. 



SPECIAL REPORT 



DISEASES OF CATTLE. 



after receiving- an injection of tuberculin, 

 50% reacted after one week, 60% after two 

 weeks and nearly all of them after a period 

 of one month. Records of tlie Prussian sea- 

 quarantine stations show that tuberculous 

 cattle previously treated with tuberculin will 

 always react when five times the ordinary 

 dose of tuberculin is administered. Vallee's 

 experiments have shown that cattle will re- 

 act to double doses administered 36 to 4S 

 hours after a previous injection of tubercu- 

 lin. In these cases, however, reactions set 

 in earlier C4th to 9th hour) and are of 

 shorter duration so that temi^eratures should 

 be taken at 2 hourly intervals immediately 

 after the injection. 



It is of interest to note that horses 

 (Bang), goats (Eichhorn), monkeys and 

 swine react to the tuberculin test. The test 

 in dogs seems somewhat less i-eliable. 



Oplitlialiiiic Reaction (ophthalmo reaction, 

 conjunctival reaction). — This test in a modi- 

 fication of the ophthalmic test as devised by 

 Calmette and T\"olff-Eisner. A strong solu- 

 tion 20 to 50% tuberculin O. T. is emploj^ed. 

 (Hutyra and Marek recommended •"»0% O. T. 

 bovine.) Dry tuberculins are especially rec- 

 ommended. 



Teohnif (ophthalmic reaction). — The head 

 of the animal is held by an assistant and the 

 tuberculin is applied to the conjunctival 

 sack and the closed eye gently massaged. 



A positive reaction is denoted by a puru- 

 lent oonjunetiviti»i which appears after 12 to 

 24 hours and may persist for three to four 

 days. A repetition of the test after 24 hours 

 in doubtful cases accentuates the reaction in 

 positive case.«. This test has tlie advantage 

 <it° not aireotinK' milk flo^-, an<l a previous 



GH, HICKMAN, LAW, 

 , PEARSON, 

 ;OWER. 



N, 1916. 



1916. 



.x>TG OFFICE. 



