Report of State Veterinarian. 49 



planned and carried out in Canada more than 15 years ago. It is 

 impossible with any amount of money to jump into the midst of 

 a widespread outbreak of hog cholera and control it. The neces- 

 sary laws must be passed and the money appropriated for the work 

 in advance is that each little outbreak can be stamped out before 

 the disease spreads beyond control. 



There are two factors which will enter into the future work 

 for controlling hog cholera which have not heretofore been put 

 into practice, viz. : Immunizing and breeding immune. Both of 

 these are now well enough understood to be used to some extent, 

 at least, and it is possible that by their extensive use the hog 

 cholera may be stamped out absolutely. Although the method for 

 immunizing hogs against cholera and the one for breeding them 

 immune from it are more or less crude and untried, there is no 

 doubt about the complete success of either. If these methods can 

 be put into general practice, which is entirely feasible, the disease 

 can be controlled without any law restricting the movement of 

 stock hogs and with much less expense. 



IMMUNIZING. 



The fact that hogs may be completely immunized against 

 cholera has been thoroughly demonstrated by the Federal Bureau 

 of Animal Industry and verified by the Missouri Experiment Sta- 

 tion. A hog which is known to be immune from cholera is used 

 in the beginning of the operation. The fact that he is immune 

 from cholera is ascertained by his having gone through an out- 

 break of cholera without taking it or has taken it and recovered. 

 This hog is injected with a culture of hog cholera germs. The re- 

 action from this injection causes a still more intense immunity and 

 the hog is spoken of as "hyper-immunized." The blood of the 

 hyper-immunized hog is drawn by cutting off a short section of 

 his tail. The serum of this blood is injected into the hog, which 

 is to be immunized. Injected alone, the serum produces temporary 

 immunity. By injecting a small quantity of a culture of hog 

 cholera germs at the same time the serum is injected, the im- 

 munity is made to last for a long while, if not permanently. The 

 blood of the hyper-immunized hog is drawn some 8 or 10 days after 

 he is given the hyper-immunizing dose. It may be drawn several 

 times thereafter, only a very short section of his tail being cut 

 off each time. A large hog is best suited for the purpose of pro- 



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