390 DISEASES OF SWINE 



this way become a source of protection to the animal against any- 

 future attacks of hog-cholera. 



It has been reported that serum makers who were putting out 

 a questionable grade of serum have in some instances sent out 

 what was supposed to be virulent blood, which was not taken 

 from a sick animal at all, but was simply blood from a healthy 

 animal, and in some cases was even reported to be nothing but 

 serum placed in virus-labeled bottles. It is, of course, easy to be 

 seen that the use of a "virus" of this nature could not produce 

 any good results. Fortunately, it is not likely to produce any 

 direct harm, but does result in harm later on when the animals 

 may become exposed to cholera. Animals which had been treated 

 with a virus which was of no account would, of course, only have 

 a temporary protection, and they might later on take the disease. 

 Such cases as these have led to wrong opinions being formed re- 

 garding the double method of treatment. 



It can be put down as an absolute fact that if the serum-simul- 

 taneous method of treatment is properly given by a competent 

 veterinarian, with a tested serum and a virus which is known to 

 be capable of producing the disease, immunity will be developed, 

 and that immunity will last as long as the animal lives. Not 

 only this, but there is practically no danger whatever of the ani- 

 mal developing an attack of cholera as a result of the adminis- 

 tration of the virus blood when accompanied by the proper pro- 

 tective dose of the virus. 



Not only will animals so treated develop the power to over- 

 come an attack of cholera, such as they might meet with by ex- 

 posure in pens that had become infected with cholera germs, but 

 they will be able to withstand the attack of one thousand times 

 the fatal dose of hog-cholera virus, even if it be injected directly 

 into the veins of the animal, as in the process of manufacture of 

 hog-cholera serum. 



The absolute absence of bad results following the use of these 

 enormous doses of pure virulent blood in the serum plants is the 

 best possible proof of the effects which follow the use of the double 

 method of treatment. Almost all the large serum plants get 

 their supply of immune hogs by taking unprotected or susceptible 

 animals and injecting them with the double method. Three 



