THIRTEENTH ANNUAL YEAR BOOK— PART IV 159 



to be put into his herd. Nobody has told us that yet. It is be- 

 lieved by some that some hogs that have the simultaneous treatment 

 become permanent carriers of cholera virus, the same as some peo- 

 ple become permanent or indefinite carriers of typhoid bacilli. We 

 Imow that is true as regards typhoid fever in the human and this 

 disease in hogs resembles it very closely. I can't answer that, and 

 I don't know any man who can. 



A Member: How long will immunization last^ 



Doctor Gibson: If properly done on any hog that weighs 100 

 pounds or over, it should be permanent; but on hogs under fifty 

 pounds no man can say whether they are permanently immunized 

 or not. 



A Member: I have a brother living at Emporia, Kansas. Last 

 year he got the cholera among his hogs. He got some of the sj'rura 

 from the Kansas Agricultural College and inoculated the hogs after 

 the disease had appeared. He lost about eighty per cent of them, 

 and afterwards it was claimed by some people that the serura was 

 probably too old or had lost its potency. 



Doctor Gibson : That could be, and that was serum only. The 

 government has given us some tests on serum five years old setting 

 on a shelf exposed to all the changes of temperature, and had it 

 protect a hog against a proper dose of virus. Of course, that is an 

 extreme, but it is believed that serum carried over a year is good, 

 and if it was once good, it is liable to be good until you have used 

 ir, for any reasonable length of time. 



They have learned some lessons in Kansas. They recommend 

 now that you give a hog a dose of serum first and prepare him 

 for the simultaneous, and then when you give him the simulta- 

 neous he will not be sickened by it, or killed, or so apt to develop 

 cholera. Every firm that is at all conscientious tells you when 

 they send you serum and virus that you are liable to lose two to 

 five per cent of your hogs when you treat them. They view the 

 average herd of hogs in Iowa as 100 in number — I think they would 

 average that — and that means that two to five hogs are going to 

 die from that treatment. What do they die of? They die of chol- 

 era. There will be another five per cent that will have spots on 

 their bellies, showing that they have cholera and may pull through. 



A Member : How long should it be between those two treatments? 



Doctor Gibson : They should be ten days apart. They now call 

 it three treatments : serum treatment, serum simultaneous, and dou- 

 ble method. 



