PREPARATION OF ANTI-HOG-CHOLERA SERUM 117 



4. Identification mark, enabling the manufac- 

 turer to trace the exact history of any bottle of 

 virus. 



5. Eeturn date, or latest date on which the virus 

 may safely be used. 



6. Directions for storing. 



7. Brief directions for using, and cautions to 

 be observed in destroying unused virus. 



Hog cholera virus is dangerous material. One- 

 half mil or even less will readily kill an ordinary 

 susceptible hog if protective serum is not admin- 

 istered in conjunction with it. Thus hogs given 

 simultaneous treatment in the field actually re- 

 ceive, as a routine measure, a lethal dose of virus. 

 It is really remarkable that this practice results 

 in so little trouble, but potential danger, slight 

 though it is, exists whenever virus is used, and 

 this fact should be well understood both by the 

 veterinarian and his client. Under no circum- 

 stances should virus be used by untrained men. 



