292 SWINE PliACTICE 



cholera in swine would be materially diminished. Since the advent of 

 anti-hog cholera serum the enforcement of sanitary regulations has 

 been neglected. In order to obtain and enforce efficient sanitary 

 measures the pork producers must first be educated to the necessity of 

 such measures. 



The application of some of the simple sanitary rules have proved 

 of great monetary value to swine raisers. As an illustration, the 

 separation of the infected from the healthy swine following the use 

 of a clinical thermometer, and the proper after-care, have been the 

 means of saving over fifty per cent of many infected herds. If as 

 much consideration were given to proper hygienic care and sanitary 

 control, as is given to the production, distribution and application of 

 serum, hog cholera would soon become a much less serious disease. 



Preventive treatment. — The first use of serum for the prevention 

 of hog cholera was made in 1897 by Preisz, who obtained it from a 

 swine that had recovered from cholera. In 1904 De Schweinitz and 

 Dorset demonstrated that hog cholera was caused by a filtrable virus, 

 and soon after, Dorset, McBryde, and Niles devised a plan of hyper- 

 immunizing swine for the purpose of producing anti-hog cholera 

 serum. This serum came into general use about 1908, and is now 

 being used extensively in the United States. 

 , It is prepared on the following general plan, different manufactur- 

 ers having slightly different methods. 



The production of serum is of considerable importance, and a brief 

 description of the general process follows: 



Swine having a large carcass and weighing 225 to 275 pounds are 

 selected, and if they are not known to be immune they are simul- 

 taneously immunized. Swine must have been immune for not less 

 than 60 days prior to hyperimmunization. The swine used for hyper- 

 immunes may be tuberculin tested and the reactors discarded. A 

 prerequisite of the hyperimmunizing process consists in having all 

 instruments and equipment sterile and environments that are con- 

 ducive to asepsis. The immune swine that are to be hyperimmunized 

 should be kept in a pasture or yards that are concreted to prevent 

 undue filthiness. The virus used is obtained by injecting healthy, 

 susceptible pigs with one or two cubic centimeters of virus. A pig 

 weighing from sixty to ninety pounds is usually used. The virus 

 pigs should be carefully observed, and temperature records main- 

 tained. If susceptible pigs have been injected with a virulent virus 

 there will be evidence of the disease in four to seven days, and from 



