THE SERUM TREATMENT OF HOG CHOLERA 785 



The immunized hogs are bled aseptically from the tail by snipping off the tip, 

 and 5 c.c. of blood per pound of weight is collected hi sterile vessels. Each animal is 

 bled once a week until three or four bleedings have been made. 



In about one week after the last bleeding they are hyperimmunized again by 

 giving them 4 or 5 c.c. of infected blood per pound of body weight, and additional 

 bleedings are made so long as the tail lasts . 



The serums secured in the several bleedings are mixed together. The third or 

 fourth bleeding is said to be most potent or to contain the greatest number of anti- 

 bodies. 



In testing and standardizing the immune serum, six hogs, weighing about 100 

 pounds each, are placed in an infected pen. No. 1 receives no serum and is a control; 

 No. 2 receives 15 c.c. of serum; No. 3 receives 20 c.c.; No. 4 receives 30 c.c.; No. 5 

 receives 35 c.c.; and No. 6 receives 40 c.c. of immune serum. The animals are 

 allowed to remain in the pens until the control succumbs and the protecting dose of 

 serum has been determined. In this manner we can determine just about the amount 

 of serum required to protect 100 pounds of hog. The Pennsylvania Live Stock 

 Sanitary Board has found that it does not require quite 40 c.c. of serum, but this 

 amount is recommended for safety, and because the weight may not be judged 

 accurately. 



Hog-cholera serum is used in both the prophylaxis and the thera- 

 peutic management of this disease. For prophylactic purposes for each 

 100 pounds of hog 40 c.c. of serum are injected. These injections are 

 usually given subcutaneously and occasionally intramuscularly. In 

 some instances active and passive immunization is practised by the 

 simultaneous injection of 2 c.c. of virus, together with 40 c.c. of immune 

 serum per 100 pounds of weight. Owing to the danger of spreading the 

 disease, this method is not generally employed. 



The results of prophylactic immunization are excellent, and the 

 method is valuable in checking epidemics. Immunity is said to last for 

 six months after vaccination. 



For curative purposes the serum has yielded good results, providing 

 it is administered not later than the fourth day after the animal shows 

 evidences of the disease. Several injections may be required, and the 

 intramuscular route should be chosen, because quicker absorption is 

 thus insured. 



Calf cholera serum has been prepared by immunizing horses 

 with strains of colon, paracolon, and other bacilli belonging to these 

 groups, isolated from calves dying of calf cholera. The immune serum 

 should agglutinate the microorganisms used in its production in dilu- 

 tions of 1:2000 to 1:500. 



This serum has proved of value in the prevention of calf cholera, 

 and may be of benefit in the treatment, providing that it is prepared 

 with the same strain or strains of microorganisms responsible for the 

 infection. 

 50 



