INFECTIOUS DISEASES 293 



the seventh to the uhitli day the temixsrature of the pig will probably 

 range from 105 to 108 degrees Fahrenheit, and is then prepared for 

 slaughter by thoroughly washing- and applying some disinfectant to 

 the skin of the ventral surface of the body. In addition to these 

 precautions the inferior cervical region is shaved. The entire pig is 

 shrouded with moist, antiseptic gauze to prevent any particles of dust 

 from dropping into the vessels used in collecting the virus. The blood- 

 vessels are severed, and the blood is collected in a sterile vessel and the 

 fibrin whipped and removed. The remainder of the blood is filtered 

 through gauze, and constitutes the virus blood. The virus pig is then 

 autopsied, and if lesions of cholera are not found, or if lesions of 

 other diseases are found, the collected virus blood is discarded. 



Hyperimmunizing is accomplished by the intravenous injections 

 of virus. For the hyperimmunization at least five cubic centimeters 

 of virus are used to the pound weight of the hog that is being hyper- 

 immunized. This quantity is given as a single injection. In the in- 

 travenous method the injection is made in an ear vein after properly 

 cleansing and securing the animal; Various devices are used in mak- 

 ing the injection. The principle involved is to force the virus into 

 the vein slowly. The virus should be near the body temperature when 

 injected. In the intra-muscular method the virus is injected in the 

 interstices between the muscle bundles, selecting two, three, or four 

 locations, as the inner thigh muscles and the subscapular region. The 

 intraperitoneal injection is made by passing a long needle through the 

 abdominal parietes into the peritoneal cavity. 



The hyperimmunes are kept in clean, sanitary pens and a temper- 

 ature record maintained in order that the producer may know when 

 the reaction is over. When the temperature assumes the normal the 

 blood contains the antibodies. Two methods of bleeding hyper- 

 immunes are in use — the slaughter method and tail bleeding. By the 

 slaughter method practically all of the blood is obtained. By the tail- 

 bleeding process from two to three bleedings are made, and the swine 

 are re-hyperimmunized, and after the reaction they are used for 

 bleeding. Sometimes the hyperimmune is tail bled for one, two, or 

 three times and then slaughtered. Each method has some advantages 

 and some disadvantages. The slaughter method is the most rapid — 

 in other words, more serum can be produced in a given length of time 

 than by tail-bleeding. Tail-bleeding is the most economical method 

 of producing serum, and antiseptic precautions can be carried out 

 more effectually. 



