364 



PEINCIPLES OP VETERINARY SCIENCE 



from the blood of hogs rendered hyperimmune to the disease by- 

 several large doses of hog cholera virus inoculated at weekly- 

 intervals. 



Anti-hog-cholera serum when injected alone confers a tempo- 

 rary or passive immunity that lasts from six to ten weeks. If 

 virus is injected simultaneously with the serum, a mild form of the 



Fig. 93. — Kidneys from a cholera-infected hog showing the characteristic small 

 red dots which give a "turkey egg" appearance. 



disease is set up from which the animal quickly recovers and is 

 rendered immune for at leasta year and in many cases for life. 



The serum is injected under the skin at any convenient place, 

 but some distance from where the virus is introduced to prevent 

 the two fluids from mechanically mixing after injection, which 

 would cause them to neutralize each other and be ineffective. 

 The skin at the point of injection should be cleansed with soap and 



Digitized by Microsoft® 



