356 DISEASES OF SWINE 



Just as soon as the end of the tail has been clipped off it begins 

 to bleed vigorously. As a rule, three small jets of blood are given 

 off, the larger one being above the two smaller ones located on the 

 same level beneath the center of the organ. This bleeding tail is 

 now held over the open mouth of a perfectly clean glass bottle or 

 granite pail and the blood allowed to flow in. If a clot forms in the 

 end of the severed blood-vessels the flow can be quickly stimulated 

 by thumping on the end of the tail with the end of one of the fingers. 



Amount of Blood to Be Drawn. — This is the next question of 

 importance. How much of the blood can we withdraw at one time 

 from the animal without killing him or seriously impairing his 

 strength and vitality? Many experiments have been made along 

 this line, and it is the general opinion that about 5 c.c. can be drawn 

 for each pound of body weight. A little over this amount of blood 

 is drawn, as there is considerable shrinkage in separating the clot 

 and filtering the product. For instance, if the hog weighs 160 

 pounds 800 c.c. of serum should be drawn. This will mean the 

 withdrawal of about 900 c.c. of blood. 



As soon as the desired quantity of blood has been drawn from 

 the animal the tail is tied off with a firm cord ligature, and the end 

 painted with tincture of iodin and covered over with tar. This 

 tying should be as tight as possible, otherwise the animal may 

 continue to bleed for several hours, and lose an enormous amount 

 of valuable blood. The tar, if placed over the cut end of the organ, 

 prevents flies from getting at the raw surface and forming a sore. 



The hog is now released and turned back into the pens to wait 

 another week before being bled again. Record is made on the 

 identification card of the number of the hog, the date, weight, 

 amount of blood drawn, and condition of the hog. 



This tail bleeding is repeated for three bleedings, at intervals 

 of one week each. At each bleeding the animal is again weighed, 

 and the amount of blood to be drawn is found by figuring on a 

 basis of 5 c.c. for each pound weight. One week after the third 

 bleeding the animal is again brought in and given an injection with 

 hog-cholera virus. At this time there is again injected 5 c.c. of 

 virus to each pound of body weight. The virus at this time is 

 injected into the veins of the opposite ear from that used on the 

 former occasion. This process of reinjecting with virus blood is 



