METHODS OF USING A NTI- HOG- CHOLERA SERUM 143 



animals thus handled, but the fact that many lots 

 of hogs will endure it, leads some to think that all 

 ought to do so. Individual differences exist, and 

 while they are not always obvious, the lots that 

 "break" more often consist of hogs that have 

 been held in stockyards a long time, those badly 

 infested with parasites, or suffering with respira- 

 tory diseases. Distances traveled to and from the 

 stockyards, and the degree of crowding of the cars 

 are also potent factors in determining the hazards 

 of shipping simultaneously treated hogs. 



Hogs are not fit subjects for simultaneous treat- 

 ment just as they are unloaded from long railway 

 journeys. It is best to give these animals serum 

 alone at this time, and simultaneous treatment 

 two or three weeks later. This is the follow-up 

 treatment which we have already mentioned, 

 and which will be considered separately in this 

 chapter. 



In farm hogs, weaning, castrating, ringing, and 

 the absurd practice of knocking "black teeth" out 

 of all pigs may operate individually or collec- 

 tively to lower resistance and render simultaneous 

 treatment dangerous. Due to pressure of other 

 work pigs are frequently neglected several weeks, 

 then suddenly there is a desire to do all of these 

 things, and immunize, at the same time, in order 

 to avoid handling the animals more than once. 

 The wonder is that pigs will frequently, even usu- 



