ELEVENTH ANNUAL YEAR BOOK— PART VII 349 



On herd No. 14 we planned an experiment to show what could be done 

 by treating a herd before disease appeared. We planned our work that 

 fall so as to gain information on several different points. We wanted to 

 know what could be accomplished in a sick herd by the use of hyper im- 

 mune serum. Again, we wanted to know if we went to the farm before 

 disease appeared what could be done. Still again, we wanted to know 

 whether after disease appeared in a given neighborhood, could we keep 

 it from extending over the entire country. Incidentally, we wanted to 

 learn whether we could vaccinate old hogs, shoats and pigs successfully 

 or whether we could only successfully vaccinate shoats or whether we 

 could vaccinate all ages. We knew very little about the dose also. We 

 might give too little or too large a dose and we wished to gain some in- 

 formation regarding it. In the experiment on herd No. 14 then we wished 

 to learn if we treated this herd while it was well if we could prevent 

 disease appearing later. There were twenty-seven in the herd. We vac- 

 cinated twenty of them and left seven untreated on October 16. No dis- 

 ease appeared in this herd until November 20, a little over a month after 

 treatment. On November 20 one of the check shoats appeared slightly 

 sick. On account of the distance we were not able to visit the farm again 

 until December 18. At that time four of the checks had died and two 

 others were sick. The seventh had been butchered by the owner. Event- 

 ually the seven hogs all died, or the six, the one having been killed. 

 None of the treated hogs were sick. We thought we had in this experi- 

 ment an illustration of the fact that if the herd was treated before dis- 

 ease appeared they would not sicken. There was disease in the neigh- 

 borhood and the seven had contracted it by its being carried to the farm 

 from some other place. 



One of the most interesting herds to me was No. 32, a herd of pure 

 bred Durocs. Some of my Duroc friends may suppose that Duroc hogs do 

 not contract hog cholera. I might say that they are a little more immune 

 than others. All breeds will contract cholera but there is a little differ- 

 ence in susceptibility. This herd consisted of spring shoats, old sows and 

 young pigs and I had an opportunity of vaccinating animals of different 

 ages. We had very little serum at this time but I made a survey of the 

 laboratory and got together enough serum to treat the herd. When I 

 visited the farm I found marked evidences of hog cholera. He had a 

 bunch of male animals which contained a number of sick ones, then a 

 large number of young gilts and a few old sows with young litters. Of 

 fourteen male animals treated two died. Several of these were quite 

 sick and a few developed symptoms of disease after treatment. Some of 

 these animals received treatment from the fact that disease was already 

 present. We do not recommend our hyper immune serum as a rule when 

 disease is present but I will say that in a number of instances it has been 

 found that animals with a mild form of disease will recover. In the four- 

 teen male animals treated only two died, while some of the others had a 

 mild type of disease and recovered. Out of the thirty-eight gilts treated 

 three died and of the twenty-seven untreated animals only five survived. Of 



