CLINICAL EVIDENCE OF VALUE OF SERUM 483 



after being castrated the disease made its appearance in the check 

 boars and also in some of the treated animals. Eventually all 

 the check boars died and also one of the treated boars. The old 

 sow which was left as a check became sick, and Hngered along for 

 some time, but finally died. All of the check shoats died except 

 one. Of the 30 shoats treated by use of the serum alone, only 

 4 died. 



In this experiment the results are a little questionable, as the 

 virus blood used was afterward found to have been of rather weak 

 quality. For this reason the animals which received the double 

 treatment in this case in reality were receiving only a single treat- 

 ment, as the virus injected was comparatively worthless. As the 

 disease did not appear among the boars until some time after 

 treatment, it is quite possible that the protective power given by 

 the serum had in part worn off, and this explains how these animals 

 became sick later on. However, the results were quite satisfactory 

 on the whole, as in the case of the untreated boars all were lost, 

 while of the 22 treated boars only 1 died. 



In this herd we have an example of the manner in which danger 

 is increased by performing any surgical operation after adminis- 

 tration of serum. Even though in this instance the castration 

 was not done until two weeks later, it undoubtedly had an im- 

 portant part in the lowering of the vitality of the young boars 

 to the point where they became susceptible to the disease. No 

 ringing, castrating, or other surgical work should be done in the 

 herd during the time when there is danger of an outbreak of chol- 

 era. It is a good plan to wait at least three or four weeks after 

 the use of the double treatment before doing any of these surgical 

 procedures. 



We have in this herd also an example of the importance of 

 using a tested virus as well as a tested serum in giving the double 

 treatment. The results from the simultaneous treatment are 

 bound to be disappointing unless care is taken to see that the 

 virus used, as well as the serum injected, is of proper quality. If 

 the virus be worthless, then the treatment is simply a serum-alone 

 treatment, and the protection against hog-cholera will only last 

 for a short time — about three to six weeks. It must be remembered 

 that it is the virulent blood in this double treatment that causes 



