514 MANUAL OF FABM ANIMALS 



live weight of hog. Thus a 100-pound hog should receive 1000 

 c.c. of virulent blood taken from a hog sick with cholera. 



This virulent blood may be obtained by allowing the cholera 

 hog to bleed to death, taking care to collect the blood free from 

 particles of dirt; or it maybe obtained by clipping the end of the 

 tail and allowing it to flow slowly into a jar well protected from 

 dirt. If the tail stops bleeding, thump it or cut the end again. 

 After collecting the blood, gently stir it with a clean stick, or 

 better still a glass rod to remove the clot. The clot will collect 

 on the rod while stirring. This diseased blood from which the 

 clot has been removed is now ready to inject into the muscles of 

 the supply hog. This is done with a hypodermic syringe and 

 inoculated into the inner side of the thigh after placing the pig 

 on his back. There are two methods of inoculating, — the 

 slow method, and the quick method. By the slow method, in- 

 creasing amounts of virulent blood are injected at regular inter- 

 vals, which requires so much time that it is seldom used. By the 

 quick method, the virulent blood is all injected at one time. 

 After the injection of this blood, the supply animal is said to 

 be hyper-immunized. 



One week after the injection of the virulent blood into the 

 supply animal, the hog is ready to have his blood drawn for 

 the purpose of protecting hogs from cholera. This blood may 

 be drawn in two ways : the supply animal may be killed and the 

 entire supply of blood taken at once, or he maybe bled at the tail. 

 The tail should be thoroughly cleaned, disinfected, and then the 

 end is cut off and the blood caught in a clean jar. Much care 

 should be used to keep everything clean and free from germ-laden 

 dirt. In this way, 500 c.c. of blood may be drawn at one time. 

 This may be repeated three times at intervals of one week, after 

 which the blood gradually loses its protective properties and 

 should not be used. 



The blood, thus collected is allowed to clot, after whicli it is 

 filtered through sterilized gauze in order to get the serum or the 



