440 DISEASES OF SWINE 



time, and the results give proof that in both cases the defense given 

 was of sufficient power to prevent any harmful effects. 



Herd Number Eight. — This herd was located in the southeast 

 quarter of Section 1, Grant Township. The owner of these hogs 

 had already had an outbreak of cholera on his premises, and had 

 lost nearly all of his herd. He was anxious, however, to test the 

 effects of the serum in protecting new hogs that were to be placed 

 in the disease-infected feed lots. 



In order to carry out this experiment, 12 shoats were purchased, 

 each weighing about 100 pounds. These animals were bought 

 from a farm where cholera had not been present, and they had 

 no opportunity of having been exposed. He also purchased 4 

 smaller pigs from another farm on which there had been no 

 cholera. 



Of the first lot of 12 shoats, 11 were injected with 20 c.c. each 

 of serum and with 2 c.c. of the virus blood. The twelfth pig of 

 this lot and the 4 smaller pigs were left untreated, and the entire 

 lot, treated and untreated, were placed in the diseased feed lots. 

 In this feed lot there still remained a few animals suffering from 

 the chronic type of cholera. 



For some reason the infection appears to have died out very 

 rapidly on this farm, as neither the injected nor the untreated ani- 

 mals took the disease. Either the disease germs that had been 

 present were already killed out, or these pigs had by some means 

 developed a resistance beyond the natural against cholera. 



While the experiment was not satisfactory as a demonstration 

 of the protective power of the double treatment against cholera, it 

 does show a few interesting points: 



In the first place, it shows that with a first-class hog-cholera 

 serum shoats weighing as much as 100 pounds can be safely 

 protected by as small a dose of serum as 20 c.c, and this even 

 when given double the usual dose of virus blood used in regular 

 field work. 



This experiment also offers further proof of the fact that there 

 is but little if any danger of infecting the premises from placing in 

 the feed lots animals that have received the double treatment. 

 Here we have 5 unprotected hogs placed in the same feed lot with 

 11 shoats that had been given the double treatment, and none of 



