350 DISEASES OF SWINE 



Keeping Needle in Vein. — Many operators have reported 

 trouble in keeping the needle in the vein once it has been properly- 

 inserted. The least movement upon the part of the animal is 

 likely to jerk the instrument out of position unless some means be 

 used to prevent the occurrence of such a mishap. Once the needle 

 has been jerked out of the vein it is very difficult to get it back 

 in position, and often it is necessary to change the field of opera- 

 tion to the opposite ear. To prevent this occurrence the best plan 

 is to make use of some sort of clamp or forceps to hold the needle 

 firmly in place. A small artery forceps can be used for this pur- 

 pose and clamped down over the needle behind the point of en- 

 trance into the vein. Special clamps are also obtainable for this 

 purpose. 



Subcutaneous Injection of Virus. — Some serum manufac- 

 turers in this country make use of a method of injection of hog- 

 cholera virus in which the virus is placed under the skin instead 

 of being introduced into the vein, as in the preceding method. 

 This plan is also used to a considerable extent in European coun- 

 tries. The subcutaneous method is sometimes known as the 

 Hungarian method, owing to its extensive use in the serum plant 

 in Hungary. 



There are two principal methods of using this subcutaneous 

 method of hyperimmunization. One is to inject increasingly 

 larger doses of virus each day for three injections. The three 

 injections are given at intervals of three days to a week apart. 

 In Hungary the interval between injections is even longer. This 

 is known as the slow subcutaneous method. It was originally 

 used by the United States Bureau of Animal Industry serum ex- 

 perts, but has since been discarded in favor of the intravenous 

 method. Another method of subcutaneous injection, known as 

 the rapid subcutaneous, is to inject at one time a large amount of 

 virus beneath the skin. This may be pure virus or pure virus in 

 connection with normal salt solution. In either case, the amount 

 of virus injected must be larger than that used in the intravenous 

 method. 



There are some advantages and a number of disadvantages 

 to the use of the subcutaneous plan of hyperimmunization. The 

 principal advantage of the method is its convenience. It is much 



