394 DISEASES OF SWINE 



feed lots in dark, damp corners, protected from sunlight, for as 

 long as a year, but the virus must have an animal body to live in 

 if it is to reproduce and keep up its power of producing disease 

 beyond that length of time. 



Care in Destroying Virus. — At the end of the injection of a herd 

 of hogs there is frequently left over a small amount of serum, and 

 perhaps a small amount of virus. The question is. What should 

 be done with this unused serum and virus? Can they be used 

 later on? 



The answer to this question must depend somewhat upon the 

 conditions. If another herd is to be treated the same day, or even 

 the next day, the virus and serum, if kept cool, can be safely held 

 over and used on the next herd. Opened bottles of serum should 

 never be taken back to town, however, and kept to await the next 

 call for treating a herd, which may not be for a week or more. The 

 best idea is to gage your serum so that you will not have more than 

 100 c.c. at most left over, and this can be very easily used up by 

 giving a httle larger dose to the last few animals when you see that 

 you have a little more opened up than you are going to need. It 

 is not possible to do any harm by giving a httle bit more of the 

 serum. The greatest danger lies in cutting the dose short, and not 

 giving enough to produce the results desired. 



With the virus it is an entirely different matter. It is not ad- 

 visable to increase the dose of virus above that given in the above 

 table of dosage. Remember that this virus is the disease-producing 

 blood itself, and it is capable of causing the death of the animal 

 very rapidly if improperly handled. With a first-class serum there 

 would be but Httle danger, even if larger doses of virus were to be 

 given. It is not wise to do so, however, as there is nothing to be 

 gained by it. The dose of virus mentioned above is plenty large 

 enough to stimulate the cells of the body and start them to produc- 

 ing large numbers of the germ-fighting bodies, and this is what we 

 wish to accomplish with the use of the serum-simultaneous treat- 

 ment. 



It is quite easy to estimate about the amount of virus that you 

 will need for a given herd — in fact, much easier to estimate this 

 fairly close than it is with the serum. If any of the virus be left 

 over, do not, under any condition, throw it out on the ground, as I 



