HOG CHOLERA 281 



than this because the blood gradually loses the properties 

 that it has acquired by the hyper-immunizing process and 

 will no longer protect hogs from hog cholera. 



After the blood has been collected by either one of the 

 methods here described, it is allowed to clot, and then 

 is filtered through sterilized gauze so as to get the serum 

 or the liquid part of the blood separated from the clot. 

 The serum or the liquid portion is the part that is used. 

 This is mixed with a five per cent solution of carbolic 

 acid, making a .5 per cent solution, in which form it is 

 more easily preserved. 



Use of the Serum. — In order to protect hogs from hog 

 cholera, they are inoculated hypodermically, as previous- 

 ly stated, with the hog cholera serum. In order to pro- 

 tect hogs from this disease, they must be inoculated with 

 the serum before they have contracted the disease, or at 

 least within four days after being exposed. Twenty to 

 thirty c. c. of this serum is used for a hog weighing 30 to 

 75 pounds. If a hog is thus inoculated with this serum, 

 he will be rendered temporarily immune, and his immun- 

 ity is supposed to last several weeks. Such immunity, 

 however, is not as great as by means of the serum simul- 

 taneous method. 



According to this method, the hog is inoculated with 

 this serum, which is usually injected into the muscle of 

 the thigh on one side of his body, and at the same time, 

 two or three c. c. of virulent hog cholera serum, obtained 

 from a diseased hog and prepared in a way so that the 

 clot has been removed from the serum, is injected into 

 the muscle on the inside of the thigh of the other side of 

 the body. Two to three_ c. c. of virulent hog cholera 

 serum is considered a fatal dose when injected into a hog 

 without the serum from a hyper-immune hog, and will 



