ELEVENTH ANNUAL YEAR BOOK— PART VII 347 



preparations have stood the test. Some are used with apparently good re- 

 sults but when tested further they have all failed and there is no known 

 drug so far discovered to cure or prevent hog cholera. The only success- 

 ful method is by hyper immune serum. 



Hyper immune serum was first used in 1906 at the bureau station at 

 Ames. It was tried in a limited way on a few susceptible animals. We 

 were not able to go into the country that year but we made preparations 

 to do that in 1907. Fortune favored us very much in 1907. It was late in 

 the season before we had obtained sufficient serum to go out but along in 

 September cholera became very prevalent in Story county within reach of 

 our station and it was exceedingly virulent. We found also that the 

 farmers were more than willing to co-operate with us in making the ex- 

 periment. They turned their herds over to us knowing that there was 

 no other successful treatment. We went out and treated something like 

 fifty herds under natural conditions. In treating that many herds of 

 course we had a variety, some were small, some large, some ordinary, 

 some thorough-bred breeding herds which had the very best of care 

 and they were located on different farms and kept under very different 

 conditions. I will call your attention to results in a few of those herds. 



I wish to show the mortality in some of the untreated herds. As soon 

 as the farmers in that district learned that they could arrest the disease 

 in their herds they all came after us. There were, consequently, a great 

 many herds left untreated as we could not go to all of them. One herd for 

 example contained 205 animals and only eleven survived. In another 

 herd of thirty only eight survived; in a herd of thirty-five six lived; in 

 a herd of thirty-seven three lived; one herd of 100 all died; in a herd of 

 thirty-six three lived; in a herd of twenty-four six survived; in another 

 ninety per cent died. That was about the proportion of surviving animals 

 in herds all over the country where the disease was present. It does not 

 always appear so virulent but that year it was exceedingly so. These 

 herds fairly represent the fatality of cholera that year. 



Now I will show you the results in a few of the treated herds. One 

 man living near Nevada had lost nearly his entire herd. I did not hear 

 of it until nearly all his herd had died. Then I went to see him and he 

 said he would be very glad to purchase a few shoats if I would vaccinate 

 them. He purchased thirteen. Ten were treated with our serum. The 

 three remaining were left untreated. The thirteen were shut in the 

 hog house with the remainder of his herd — he had a few lingering cases. 

 The three were simply left to see if there was enough disease left to 

 communicate. They began in a short time to show t;:e symptoms and 

 they finally died. The ten treated shoats ran with them but remained 

 well. Of course all the neighbors heard of that, thought it was a very 

 good experiment and everybody began coming up to see if we could 

 treat their herds. 



One of the next herds was a herd in which disease had existed for 

 some time but in which a large number of animals still lived. When I 

 visited the farm on the day I started the experiment I found that one or 

 two of the old animals had died. The majority of the herd were shoats. 



