MANUFACTURE OF HOG-CHOLERA SERUM 



337 



As already stated, there is selected for this purpose a virus that 

 is of the very best quality obtainable. This is injected in doses of 

 2 to 5 c.c. into the muscles of the inner side of the thigh. The 

 injected pig is then placed in a pen and allowed to remain there 

 as if nothing had happened. He is given the usual feed at the 

 usual time each day, and every morning the temperature should be 

 taken and record made of same. Usually about the evening of 

 the fourth day there will be noted a considerable degree of fever, 

 and by the fifth day visible evidences of cholera will be noticeable. 

 The pig will be seen to be off feed and may appear droopy and be 

 scouring. 



Fig. 58. — Table for virus bleeding, horizontal position. In use at Tennessee 

 State Serum Plant. 



He is now ready to be killed, and most authorities agree that 

 it is better to kill the virus pig just as soon as possible after pro- 

 nounced evidences of cholera develop, rather than wait until he 

 is in a dying condition. In some cases it will take longer than 

 five days for signs of the disease to make themselves noticeable 

 in these virus pigs. This in large measure depends upon the 

 strength or potency of the virus blood used. The virus used at the 

 Ames serum plant produces loss of appetite and marked rise in 

 temperature, as a rule, on the evening of the fifth day. 



Bleeding of Virus Pigs. — The sick animal is now removed to the 



22 



