54^ SWINE IN AMERICA 



"Safety of the methods. — Properly prepared serum 

 used alone, without the employment of blood from a 

 sick hog, is harmless and incapable of giving rise to an 

 attack of cholera. Nor does this injection interfere in 

 any way with the growth of the treated hogs. 



"The simultaneous inoculation, involving as it does 

 the use of a disease-producing virus, requires much 

 more care when employed than does the serum-alone in- 

 oculation, for, if from any cause the serum should be 

 weaker than required, injury to the vaccinated hog 

 might result. This danger is extremely slight when 

 carefully tested serum is used. 



"In deciding which method to use one must be gov- 

 erned largely by the length of immunity which is re- 

 quired. If this is needed for only a few weeks, or if 

 the treatment can be repeated at short intervals, as in 

 the case of exceptionally valuable pure-bred hogs, where 

 the increased cost would not be objected to, the serum 

 alone may be used. In other cases the simultaneous 

 method is recommended. In either process of vaccina- 

 tion it is considered highly desirable for the treatment 

 to be applied by competent veterinarians who have had 

 special training in this class of work, and only such 

 skilled men should employ the simultaneous process. 

 After treatment by the simultaneous method the herd 

 should be kept under observation for ten days or two 

 weeks, and if any of the inoculated hogs show serious 

 symptoms of disease the herd should be immediately 

 re-treated with the serum alone. When properly per- 

 formed, the simultaneous inoculation does not seem to 

 injure the hog or interfere with its growth in any way, 



