METHODS OF USING ANTI-HOG-CHOLERA SERUM 139 



average in resistance. In using virus the label is 

 likewise our guide. Although in giving simultane- 

 ous treatment to hogs we regularly administer a 

 lethal dose of virus, we should not let that fact 

 tempt us to decrease the quantity. Too much 

 stress has been laid on carefully graded doses of 

 virus and on the necessity for balancing virus and 

 serum doses. One mil of virus will kill almost as 

 regularly and quickly as three, and an ordinary 

 dose of serum will protect against either quantity. 

 The dose of serum is not governed by the quantity 

 of virus, but by the potency of the serum, which 

 is reflected on the label, and by the size and con- 

 dition of the hog. Thus, if circumstances compel 

 us to give simultaneous treatment to hogs below 

 average in resistance, we increase the dose of 

 serum, but leave the virus dose unchanged. The 

 primary aim is to give enough virus to infect, and 

 enough serum to protect against an infecting dose. 

 In our own field work we never give less than one 

 mil of virus nor more than two mils, our prefer- 

 ence being for a dose approaching the latter figure 

 in all swine weighing more than seventy-five 

 pounds. 



After-effects and dangers of simultaneous treat- 

 ment. A reaction, very slight in the vast ma- 

 jority of cases, but severe in others, usually 

 follows simultaneous treatment. In effect, the 

 animals go through an attack of hog cholera which 



