428 DISEASES OF SWINE 



than cholera. The hog-cholera serum used in this case unques- 

 tionably proved protective, in that not one of these animals 

 proved in the least susceptible to the disease. This in spite of the 

 fact that they came from the same herd and were placed under 

 exactly the same conditions. 



The dose of serum used is also worthy of note. In this experi- 

 ment the amount of serum injected was approximately ^ of 1 

 c.c. per pound weight of the hog. This is about the average dose 

 which is being used by the United States Bureau of Animal 

 Industry in the present campaign of eradication against hog- 

 cholera. 



Herd Number Two. — This herd was located just across the 

 road from Herd Number One, and consisted of an old sow and her 

 litter of 5 shoats, averaging in weight about 75 pounds each. 

 These animals, although in close contact with the infected prem- 

 ises, had so far remained well. The owner of the herd was present 

 when the hogs on Farm Number One were treated, and, believing 

 that his own herd was in great danger owing to the close prox- 

 imity of the infection, he requested that they receive treatment. 



As the infection had not yet made its appearance on this farm, 

 the animals received the serum-simultaneous treatment. Three 

 of the pigs were injected, each receiving 20 c.c. of hog-cholera 

 serum and 2 c.c. of virulent blood. The other 2 were left un- 

 treated, to serve as checks on the experiment. In this case the 

 disease did not make its appearance at all, neither in the injected 

 nor in the untreated animals, so that in a measure the outcome 

 was uninstructive, as the serum did not have a chance to demon- 

 strate its power in the presence of infection. 



However, there are several interesting facts worthy of note 

 in connection with this herd. 



In the first place, it shows that hog-cholera is not often an 

 air-borne infection. This herd, which was located just across the 

 road from the infected yards on the first-mentioned farm, did not 

 contract the disease. This was no doubt in great measure due to 

 the fact that no direct communication was carried on between 

 the two feed lots. Cholera will not often travel across as wide 

 a space as a public road unless it is carried by man or animal. 

 Under proper sanitary conditions there is no reason why cholera 



