300 SWINE PRACTICE 



infecting and producing cholera in a cholera-free herd and establish- 

 ing new centers of cholera in a community free from the disease. By 

 the proper use of serum alone in communities where there are only 

 a few centers, cholera could be efficiently controlled. In such cases 

 the infected herd and all surrounding herds should be immunized and 

 if necessary the process could be repeated six weeks later. This 

 method of control is not as applicable when several counties of a 

 state, or the entire state, is infected. Serum alone, when given in 

 large doses, is of considerable value in the incubation period of the 

 disease before the animals show visible symptoms but after the tem- 

 perature has risen. The judicious use of serum in such cases has 

 saved as high as eighty or ninety per cent of the exposed herd. The 

 dose of serum in the serum-alone treatment depends upon the sus- 

 ceptibility of the pigs and the potency of the serum. The following 

 schedule of serum dosage for serum-alone. treatment in non-infected 

 swine has been suggested: 



Weight of Hog Dose of Serum 



Below 10 pounds 10 cubic centimeters 



10 to 15 pounds 15 cubic centimeters 



20 to 30 pounds i...20 to 25 cubic centimeters 



40 to 75 pounds 30 cubic centimeters 



100 to 150 pounds 40 to 60 cubic centimeters 



175 pounds and over 80 cubic centimeters 



The above dosage should be increased about 50 per cent. 



Serum-alone treatment is indicated in infected swine and in ex- 

 posed swine that are to be marketed within three or four weeks. 



The simultaneous method is used more extensively than the serum 

 alone, because it produces a longer immunity. The dose of serum used 

 in the simultaneous method should be fifty per cent more than the 

 dose in the serum-alone method. Not less than one mil of virus should 

 be used, and for swine weighing over 60 pounds better results have 

 been reported when 2 mils of virus were used. 



The serum and virus must be introduced separately into different 

 parts of the bodj^ This method may be used successfully in exposed 

 herds, especially in swine that do not show a high temperature. But 

 the virus should not be given to hogs that are showing visible signs 

 of cholera. Tlie one Neriiiiis disadvantage of the simultaneous method 

 is the fact that infection is introduced. Good authorities claim that a 

 hog immunized Ijy the simultaneous method does not eliminate the 

 virus unless he dies of the disease. 



The principal advantage of the simultaneous method of immuni- 



