HANDLING HOG CHOLERA IN THE FIELD 177 



Let us suppose that a breeder of pure-bred hogs 

 wishes to establish a trade for immune breeding 

 animals, and has decided to maintain a cholera im- 

 mune herd. His herd consists of two large herd 

 boars, fifty brood sows nursing litters about four 

 weeks old, fifty gilts recently bred and now being 

 sold daily in twos and threes as the trade de- 

 mands, and a herd of one hundred fattening hogs 

 that will be ready for market in six weeks. Hog 

 cholera is not threatening the herd. How is" it 

 to be handled with the greatest safety, and with 

 the least expense and inconvenience? 



The brood sows are not in the best condition to 

 receive simultaneous treatment, the gilts could not 

 be sold and shipped at once if it were given, and 

 the fattening hogs will be sold anyhow in six 

 weeks. If we wait that length of time the gilts 

 also will be sold, the young litters will be weaned, 

 and sows and pigs will be in condition to receive 

 simultaneous treatment. The two boars are thus 

 the only animals in the herd for which the delay 

 of six weeks is not positively indicated, and they 

 can be immunized as well at one time as another. 



From this concrete example we develop the sim- 

 ple rule that when choice is allowed we begin im- 

 munizing at a time when the herd is at a minimum 

 as far as numbers of adult breeding stock is con- 

 cerned, and when the animals are in condition to 

 receive simultaneous treatment with the least pos- 



