202 VETERINARY STUDIES 



5 days between treatments. Following the second treatment, 

 observations begin at about the sixth hour and continue every 

 two hours until about the twentieth hour unless plain reaction 

 occurs in the meantime. Observations may also be made after 

 the first eye treatment, if convenient. 



Tuberculous cattle react with a temporary inflammation of the 

 eye structures; for example, hyperemia of the conjunctiva, pro- 

 fuse flow of tears, pus in the eye — usually at the inner angle — , 

 and sometimes by swelling of the lid. This reaction may be 

 slight or very temporary, and the evidence, such as pus, may be 

 easily wiped off or lost. 



Any two or all of these three tests may be vised together in 

 making a combination test. Any wise combination is necessarily 

 somewhat more accurate than either of the single tests, because 

 there are a few tuberculous cattle which at any given time will 

 respond plainly to one test and not to another. 



Combination tests should be used, at least in badly affected 

 herds and in herds of great value. 



A positive reaction by either test should usually condemn. A 

 suspicious reaction by either test should at least isolate all 

 animals giving such suspicious reactions. 



