HANDLING HOG CHOLEKA IN THE FIELD 173 



through an outbreak even when they are born in 

 pens containing hogs sick with cholera, and this 

 presents no great difficulties when the sows are 

 immune, but when farrowing and recently far- 

 rowed sows are susceptible, they do not tolerate 

 virus well. Despite the fact that they receive 

 serum a few will die, other will fail to nurse their 

 litters, and on the whole results are much less 

 satisfactory than they are when reasonably effec- 

 tive isolation can be practiced. 



We do not wish to convey the impression that 

 after hog cholera reaches a herd we can prevent, 

 by isolation, ultimate infection of all the animals 

 in it for exactly the reverse is true. The point 

 we emphasize is that when the disease appears 

 among sows that are farrowing, infection of many 

 of them can be delayed by isolation, that they gain 

 valuable time, and they and their litters are in 

 better condition to withstand the effects of the 

 virus when later it reaches them, either by natural 

 means or through simultaneous treatment. A 

 sow undergoing serum-virus reaction when her 

 litter is a day or two old is in some danger of 

 death, and even if she lives lactation may cease 

 and her pigs perish. Delay the event of infection 

 four weeks, and regardless of how it affects the 

 sow the litter can be saved. The theoretical 

 grounds for handling farrowing sows in this man- 

 ner are obvious, but we recommend the plaij of 



