494 DISEASES OF SWINE 



This herd was within a half mile of an infected farm, but all the 

 animals were apparently well when first seen. The date of treat- 

 ment on this farm was November 7, 1907. The herd was made 

 up of pure-bred Berkshires of various ages and sizes. 



In this herd 12 shoats, which averaged in weight from 125 to 

 200 pounds, were each given 30 c.c. of serum with an accompanying 

 dose of 1 c.c. of virulent blood. One shoat, weighing 100 pounds, 

 was given 20 c.c. of serum with 1 c.c. of virulent blood. Three 

 fall pigs, each weighing about 25 pounds, were given 20 c.c. each 

 of serum alone. Five small sucking pigs received 10 c.c. each of 

 serum alone. One old boar was given 60 c.c. of serum plus 1 c.c. 

 of virulent blood. Two old sows received 50 c.c. of serum plus 1 

 c.c. of virulent blood. Another group of 4 old sows received 40 c.c. 

 each of serum and 1 c.c. of virulent blood. 



Two shoats, weighing about 150 pounds each, were left un- 

 treated to serve as checks. It was the intention to later on expose 

 these checks, with part of the treated animals, on some nearby 

 infected farm. Owing to the lateness of the season and large 

 amount of other work to be done by the limited force then attached 

 to the Bureau Station at Ames it was impossible to carry out this 

 last part of the experiment. 



The later history of this herd shows that neither the untreated 

 checks nor the treated animals became sick. From this report it 

 must be concluded that cholera infection did not reach this par- 

 ticular farm from the adjoining sick herds. The experiment, how- 

 ever, is of interest, in that it gives another illustration of the use of 

 the double treatment in part of a herd without producing any bad 

 effects in the treated or untreated swine. The animals that 

 received the dose of 1 c.c. of virulent blood, in connection with a 

 proper dose of protective serum, showed no ill effects from their 

 treatment. Not only this, but they were left in the feed lot with 

 single-treated and untreated animals without producing any 

 cholera in them. This again offers proof of the fact that the use of 

 the simultaneous or double method is safe. With a proper dose of 

 a tested serum there should be no bad effects in the herds that 

 receive the double injection. These same hogs may be left in the 

 feed lots with unprotected animals without any danger of infec- 

 tion from this source. Of course, infection may reach the feed 



