352 IOWA DEPARTMENT OF AGRICULTURE 



three hundred miles of a herd if it should be vaccinated. It is not 

 necessary until it is somewhere near about. If I was going to the 

 fair I would do so. I think some states make it compulsory and it 

 is certainly the proper thing to do to vaccinate them before they 

 go to the fair. We were called upon to do this before going to Kan- 

 sas City and to the International. Probably the same will be true 

 in regard to the state fair. I would not consider it necessary to 

 vaccinate a herd of mine unless disease was somewhere near or I 

 was going to the fair or intended to introduce other hogs into the 

 the herd. We don 't need to vaccinate just because we can but we do 

 need it if there is any danger. ' ' 



F. B. Butterfield, of Polk City, Iowa, asked: ''How long does 

 vaccination last?" 



Dr. Niles: "The serum alone only lasts a few weeks but if the 

 double vaccination is used as far as we know it lasts during the life 

 of the hog. With the serum alone if they are exposed to the disease 

 too they acquire lasting immunity because they get the disease along 

 with it." 



H. S. Allen, of Russell, Iowa, asked : ' ' Can any person vaccinate 

 his own hogs, and if a sow is vaccinated with a double vaccination 

 while carrying a litter will the litter be immune ? ' ' 



To which Dr. Niles replied : ' ' They have a little immunity but not 

 entirely. I have found that while they develop the disease it is 

 not so active. By breeding animals which have been through cholera 

 you can get animals with a little immunity but not enough to make 

 it practical. I would be glad if Dr. Peters would answer the other 

 part of the question." 



Dr. Peters: I am indeed very glad to be with you this after- 

 noon and hear this discussion because I was present here some 

 years ago and discussed this subject with you when we were making 

 the serum from horses. At that time we did not know, as Dr. 

 Niles says, the mysterious feature about the virus, that there was 

 something in this blood that still produced the disease. Dr. Niles 

 and myself could entertain you for a long time in discussing some 

 of the methods we are still pursuing to cheapen the product and 

 this organization should be very proud of the work Dr. Niles has 

 done. It was through his painstaking work that this work has been 

 brought out and recognized, not only in America but throughout 

 the entire world. If you were traveling abroad that would be one 

 of the first things the scientist would say to you, the wonderful 

 work accomplished in hog cholera. As to vaccinating your hogs 



