NOTES ON ATTENUATION OF VIRUS IN THE BLOOD 
OF CHOLERA HOGS TO PREPARE A VACCINE.* 
By Robert Graham, Professor of Veterinary Science, Kentucky Agri¬ 
cultural Experiment Station, Lexington, Kentucky. 
During the time the specific cause of hog cholera was con¬ 
sidered to be the Bacillus cholera suis, there were reports of suc¬ 
cess in immunizing hogs by injecting the attenuated organism, 
and some practical hog raisers in Kentucky have great faith in 
this method and prefer it to serum and virus, for no other reason 
than that it proved successful in their herds in previous out¬ 
breaks, as prepared and administered under the supervision of 
Drs. H. J. Detmers and Paul Fischer, of Ohio, the latter now 
State Veterinarian of Ohio. We know, however, that attenua¬ 
tion by passing or registering the Bacillus cholera suis or virus 
in the circulation of a horse was not successful, though at times 
it seemed very efficient.f 
Hence this question of a true vaccine for hog cholera, pre¬ 
pared from the Bacillus cholera suis and even by heating the virus 
contained in the blood of sick hogs, is not new. The latter was 
attempted at the time Dr. Dorset proved the true cause of hog 
cholera, and even by De Swinetz, his predecessor. Irregular and 
discouraging results included the attenuation of the Bacillus 
cholera suis; the liquid, dried and powdered cholera blood, by 
heat and chemicals. So ineffective was the vaccine prepared in. 
this manner that we find no record of their work, for perhaps- 
they have discovered and realized the impossibility of a satisfac¬ 
tory vaccine in the early stages of their investigations, and 
brought them to a hasty end. 
Literature and data relating to this subject, attenuating by 
heat, are therefore relatively scarce; in fact, entirely wanting, 
* Read at meeting of Kentucky Veterinary Medical Association, February 28, 29, 1912, 
Frankfort, Ky. 
t Bulletin, Kansas Experiment Station No. 157, W. E. King. 
330 
