DISEASES OF SWINE 463 



posed to hog cholera within a short time after the injection of the 

 serum, the immunity becomes, so far as experiments have shown, of 

 permanent and lifelong duration. 



From what has been said it will be seen that the injection of the 

 serum alone is especially to be recommended in cases where there is 

 immediate danger of exposure, especially when valuable hogs are car- 

 ried to fairs and in herds where the disease has already broken out but 

 has not progressed very far. In herds of this character all of the well 

 animals may be treated, and even in the case of slightly sick animals 

 much good may be accomplished by the serum injection. (F. B. 

 379.) 



Serum alone vaccination is safe, and its use need be restricted 

 only by its cost and degree of efficiency. In our experiments in the 

 treatment of cholera-sick hogs, it has proved quite useless, but has 

 been used with some apparent success in preventing extension of dis- 

 ease in herds already infected. The problem here is to increase the 

 potency of the serum and diminish its cost. (Ark. B. 105.) 



Each pig is treated with the proper amount of serum, the dose 

 varying with age and size. It is useful with herds where the disease 

 already exists, and is used only on seemingly healthy animals. It is 

 not a cure, but a preventative, and of no use to sick hogs. The im- 

 munity lasts for a few months only in well pigs; but when used on 

 pigs exposed naturally to the disease, the animals may be considered 

 immune thereafter. It is especially useful and used extensively where 

 pigs are sold, shipped or exhibited at fairs. The usefulness and value 

 of hog cholera serum has long been considered beyond the experi- 

 mental stage. Its use has been saving over 90% of the animals 

 treated, and thousands have been treated successfully. (N. J. L. 

 S. C. Cir. 1.) 



Because of difficulties which we have experienced when using 

 the "Serum-Simultaneous Method" in the field under different condi- 

 tions than those under which the serum has been tested, we do not 

 recommend it or permit the virus to pass out of our hands for the 

 present. There is no danger in the use of the "Serum-Alone Meth- 

 od," and we heartily recommend it where hog cholera exists or in 

 cases where immunity is desired for a short period. (Mich. Cir. 6.) 



Handling the Hogs During Inoculation. Separate the well 

 from the sick or those to be treated from those not to be 

 treated. If possible, mark in some way all the hogs treated or 

 all those not treated so that the results of the treatment may be accu- 

 rately estimated. The pigs to be treated should be separated accord- 

 ing to weight in pens or enclosures, all those requiring the same dose 

 of serum being placed together. The attendant holds the pig by the 

 hind legs with the snout toward the ground and the inside of thighs 

 or hams exposed to the operator. Pigs weighing less than 100 pounds 

 can be easily held in this way. Larger hogs may be thrown on the 

 back with the hind legs spread apart and held securely. Hogs weigh- 

 ing over 200 or 300 pounds can be treated while standing by insert- 

 ing the hypodermic needle into the muscles on the inside and back 

 portion of the ham, approaching the hog from the rear. An assist- 



