392 DISEASES OF SWINE 



double treatment are usually able to withstand any ordinary ex- 

 posure to cholera during the first few weeks of their fife. The 

 protection so given usually lasts until about weaning time of the 

 pigs. Dr. Dorset, of the United States Bureau of Animal Industry, 

 and Drs. Fischer and Fitzgerald, of the Ohio State Experiment 

 Station, report a number of cases in which they have taken these 

 pigs born from sows that had been protected by the double method 

 of treatment and injected into their bodies the usual death-pro- 

 ducing dose of hog-cholera virus. These pigs were not in the least 

 effected by the virus. Other pigs, which were born from sows 

 that had never been treated when injected with the same dose of 

 the same virus, were killed. 



Pigs from these same litters, after being weaned, were again 

 injected with the virus blood and proved to be unprotected, 

 cholera appearing in the usual length of time. The type of the 

 disease which appeared even at this time was of the slow or chronic 

 type, showing that the animals still had some protective power 

 against the disease. 



This protective power which the sow gives to her litter is 

 probably, in part at least, due to the milk. The milk is a secretion 

 which is derived in large part from the blood. The blood of these 

 sows contains a large amount of the germ-fighting bodies, and it 

 is highly possible that this milk carries with it a certain number of 

 these same germ destroyers. For the young pig the dose of serum 

 necessary to protect against cholera is very small, and it would 

 require but a small number of these antibodies or protectors to 

 keep the animal free from the disease. However, as in the case of 

 the use of the serum-alone treatment, there is nothing entering 

 the body of the little pig to educate the cells of his body in the 

 manner of making these germ-fighting bodies, and, as a result, 

 as soon as he is weaned from the mother he begins to lose his pro- 

 tection against the disease and becomes susceptible. 



It is at this age that the pig should be handled and given the 

 simultaneous or double method of treatment. At this age and 

 weight the cost of the double treatment would be very small, 

 only about 25 cents for each pig. Properly given, with a tested 

 serum and a proved virus, the results can only be good. There 

 is practically no danger of loss from the treatment, the expense 



