METHODS OF USING ANTI-HOG-CHOLERA SERUM 141 



to vaccination. Most important among these may 

 be mentioned shipping, weaning, castrating, heavy 

 ascaris infestation in which the gall ducts are 

 filled with the parasites, overheating incident to 

 handling during immunization, severe exposure in 

 cold rains during the reaction period, injudicious 

 feeding during that time, and general unthrifti- 

 ness due to any cause. These are not imaginary 

 influences that may cause " breaks," but are real 

 influences that do cause them, and while they may 

 be repeatedly ignored without dire consequences, 

 the tendency is to ignore them once too 

 often. 



The practicing veterinarian is helpless in re- 

 gard to the potency of the serum he uses. He has 

 no opportunity to test it, and must therefore ac- 

 cept it on faith. His safest plan is to secure it 

 only from the most reliable sources. Of course if 

 the virus used is up to standard, and the serum is 

 impotent the hogs that receive the two simultane- 

 ously will probably die, and no veterinarian who 

 has had this result follow his work will soon for- 

 get it. It is well to remember, though, that impo- 

 tent serum is just one of many causes of so-called 

 " serum breaks" and that the remainder of these 

 causes are for the most part controlled by the 

 practitioner or breeder. There is a triple respon- 

 sibility associated with all simultaneous treat- 

 ment, and neither serum producer, veterinarian 



