24 



farmers' BULLETIN 834. 



SIMULTANEOUS INOCULATION. 



In the simultaneous method of inoculation hog-cholera virus is 

 used in addition to the serum. It has been stated above that the 

 serum alone produces an immunity which lasts for only a very short 

 time. The theory of the simultaneous inoculation is to administer 

 the germs of hog cholera in the virus and at the same time to give 

 a dose of serum which will protect the hogs from cholera. The virus 

 enters the system of the hog and causes a reaction which results in 

 immunity like that which is found in hogs that recover from a natu- 

 ral attack of the disease. The serum being given at the same time 

 prevents death or serious sickness which would otherwise be caused 

 by the virus, and through the combined action of these two agents 

 the hogs are rendered immune against cholera for life. 



In administering the simultaneous inoculation the serum is in- 

 jected in- the manner already explained, and the virus is injected in 

 the same manner but on the opposite side of the body. The virus, 

 of course, is given in a very small dose as compared with the serum. 

 The doses for simultaneous inoculation are indicated in Table 5. 



Table 5. — Doses of serum and virus in simultaneous inoculation of healthy hogs. 



Weight of hogs. 



Dose of serum. 



Dose of virus. 



Below 10 pounds 



20 to 30 pounds 



40 to 75 pounds 



100 to 150 pounds 



175 pounds and over 



10 cubic centimeters 



20 to 25 cubic centimeters 



30 cubic centimeters 



40 to 60 cubic centimeters 

 80 cubic centimeters 



i cubic centimeter. 

 \ cubic centimeter. 



1 cubic centimeter. 



2 cubic centimeters. 

 2 cubic centimeters. 



If the herd is infected, the dose of serum should be slightly increased for all appar- 

 ently healthy hogs, and all those showing high temperatures or other evidence of 

 disease should receive at least a dose and a half of serum and no virus. 



While the serum alone has the advantage of being harmless, it 

 should be remembered that it has the disadvantage of producing 

 only a transitory immunity. The conditions are precisely reversed 

 in the case of the simultaneous inoculation. In this case the im- 

 munity is prolonged, and it is rare to find a hog which has been 

 immunized properly by the simultaneous method which again be- 

 comes susceptible to cholera. The principal objection to the simul- 

 taneous inoculation is the element of danger caused by the injection 

 of the virus of cholera. If the serum should not be of proper 

 strength, or if a sufficient dose of serum should not be administered, 

 or if the work is not done properly, a case of hog cholera may be 

 produced. Sufficient work, however, has been done to show that 

 the simultaneous inoculation can be administered with safety. Cer- 

 tain important things are to be remembered in this connection. Use 



