Swine Groivers' Association, 319 



the skin into the muscle, and the serum is slowly injected. It is 

 best to divide the dose between the two sides. The serum is ab- 

 sorbed better when injected into the muscle rather than simply 

 underneath the skin. Heavier hogs which cannot be held in the 

 manner described, are laid on the ground and turned on the back. 

 The hind legs are held backward, and well apart, and the injection 

 is made in the same location as in the smaller hogs. When preg- 

 nant sows are to be inoculated they are not thrown down, but are 

 confined in a crate, or by other convenient method, so as to avoid 

 rough handling, and are inoculated just back of the ears, in the 

 deep vertical furrow which lies between the head and the shoulders. 

 A gentle sow can be inoculated in this location without confining. 

 The thigh muscle is ordinarily to be preferred to this location, as 

 the absorption is better. 



Fig. 9. Method of inoculating a large hog against hog cholera. 

 Veterinary Department, Missouri Experiment Station. 



DURATION OF THE IMMUNITY. 



When the hogs are injected with the immunizing serum alone 

 a passive immunity is conferred which probably does not persist 

 for more than three or four months. If the hogs are on infected 

 grounds at the time of inoculation, they will acquire a permanent 

 immunity. If the animals are on grounds that are not infected, 

 it will be necessary to inject them with a small quantity of hog 

 cholera virus (about two cubic centimeters). This was called by 

 Dr. Dorset the "simultaneous method." In the greater part of 

 the over six thousand inoculations which we have made, the 

 herds were on infected grounds, and it was not necessary to use 



