321 



So much for the indiscriminate use of hog cholera virus. At 

 the Oakland meeting of the American Veterinary Medical Asso- 

 ciation a symposium of articles on hog cholera in all of its aspects 

 concluded with a set of resolutions which were not even read by 

 title, it being close to midnight, but which I had an opportunity 

 to glance over. These resolutions admitted of the use of the 

 virus treatment in heavily infected territory, and then in the 

 hands only of veterinary officials or experienced sanitarians. Had 

 these resolutions come up for discussion it is doubtful if even that 

 much would have been conceded, there being present a number of 

 state veterinarians absolutely opposed to the use of virus, whether 

 in the hands of experts or otherwise. Dr. Connaway of Missouri, 

 for instance, in the above quoted article says : "There is no 

 veterinarian, no matter how expert he may be, who is always able 

 to gauge the dosage of the serum and virus so as to prevent 

 occasional disastrous results, if he honestly tries to give the 

 breeder what he is paying for, namely, a life immunity to his 

 show hogs." 



It must therefore be admitted that there is a certain amount 

 of risk connected with the use of the virus even under the most 

 favorable conditions and that this risk at times becomes prohibi- 

 tive. We also know that vaccination cholera occurs only when 

 the relation between the injected virus and the preventive serum 

 is not properly balanced, that the virus is too strong or the serum 

 too weak, or that the virus contains micro-organisms and toxins 

 against which the serum is ineffective or lacks the required 

 antitoxins. 



The point would therefore be. in districts where cholera pre- 

 vails and where there might be some excuse for the application 

 of the serum simultaneous vaccination to use virus only of the 

 strength or virulence of the infection already on the premises, 

 and avoid bringing in a stronger infection, as is frequently done 

 with commercial virus. This idea was suggested to me by Pro- 

 fessor Haring of the Veterinary Department of the University 

 of California, who has seen it used successively on several large 

 pig farms near Berkeley. On these farms where swill is being 

 fed exclusively and where the swill is not boiled, there is always 

 danger of cholera being introduced with pork scraps which in 

 smoked or cured, but uncooked forms, is said to be able to trans- 

 mit the disease. So when cholera breaks out a carefully selected 

 pig showing typical symptoms of the disease is bled to death, the 

 blood being gathered in sterilized vessels and defibrinated by 

 shaking and straining. A post-mortem examination of the carcass 

 is then made and if typical hog cholera symptoms are found the 

 collected blood is used as virus in the serum-simultaneous treat- 

 ment of all the susceptible hogs on the place. By this means no 

 new infection is brought in, but the animals are protected against 

 the infection already on the place, the use of the virus simply 



