360 DISEASES OF SWINE 



SUMMARY OF SERUM MANUFACTURE 

 We have now seen how hog-cholera serum is manufactured, and 

 it will be of interest to go back over the last few pages and sum- 

 marize the principal points of importance: 



(1) In the manufacture of hog-cholera serum it is necessary 

 to have some immune hogs. By this we mean hogs that have 

 a protective power against hog-cholera and will not take the 

 disease. 



(2) These may be obtained from a number of sources, the more 

 important being by purchasing hogs that have been through a 

 natural attack of the disease, by injecting hogs with serum and 

 turning them in exposure pens where they come in contact with 

 the germs of disease, or by treating them with the simultaneous 

 method. 



(3) It is next necessary to secure some virus blood. This may 

 be obtained from cholera hogs slaughtered at public stock-yards, 

 from sick shoats slaughtered at the commencement of an outbreak, 

 by exposing healthy pigs in an infected feed lot, or by injecting 

 healthy pigs with virus blood. 



The most scientific of these methods is by the injection of 

 healthy shoats with blood of known virulency. 



(4) This virus blood is obtained by bleeding of the sick shoats, 

 under the most cleanly conditions, from the large blood-vessels of 

 the neck. 



(5) This blood is defibrinated and filtered, and is now known as 

 virus blood. It contains millions and millions of the virus or 

 disease-producing bodies responsible for development of hog- 

 cholera. 



(6) This virus blood is then injected into the body of one of 

 the immune animals. The immune animal selected for this test 

 should have been treated by the simultaneous method at least 

 three weeks before. 



(7) The amount of virus blood to be given is 5 c.c. for each 

 pound body weight. 



(8) There are a number of ways of giving this virus, the more 

 important being by injection into the veins of the ear (intravenous 

 method); by injection under the skin of the belly (subcutaneous 

 method) ; or by injection into the peritoneal cavity (intra-abdomi- 



