176 PRINCIPLES OF VETERINARY SURGERY 



SERUMS— DIAGNOSIS, PREPARATION, ETC. 



THE TOXINS IN DIAGNOSIS:— It has been found 

 that if we inject an animal suffering from tuberculosis with 

 some toxin of the tubercle bacilli, or tuberculin, we shall 

 notice an elevation of temperature. This is called the Tu- 

 berculin Test. Similarly, if we inject some toxin .of -the 

 glanders bacilli into an animal suspected of glanders infec- 

 tion, a reaction occurs in the form of a marked swelling at 

 the site of injection, and an increased temperature. This 

 is the Mallein Test. Similar reactions are sometimes seen 

 when other infections are tested with the toxins of the cor- 

 responding bacteria, but as yet have not found universal ac- 

 ceptance. 



THE MANUFACTURE AND STANDARDIZATION 

 OF SERUMS — VACCINES : — First — Antitoxic Ser- 

 ums : These are usually prepared by injecting an animal, 

 preferably a horse, with gradually increasing doses of the 

 toxin until the animal is able to withstand a very large dose, 

 which if injected at first, would have proved fatal. This 

 process we call "Immunizing the Animal." The toxins 

 used for the injections are obtained from the living bac- 

 teria. These organisms are first grown in various culture 

 media. The cultures are then run through a Pasteur Cham- 

 berlain filter, or similar one, to remove the bodies of the 

 bacteria. The filtrate contains the toxin only, and is used 

 for immunizing the horse. 



After the horse has been thoroughly immunized, he is 

 bled, the blood allowed to coagulate, and the serum is sep- 

 arated from the clot. This serum contains the antitoxin and 

 is ready for use. 



Antibactericidal serums are produced similarly to the 

 antitoxic serums, but the actual bacteria themselves are 

 injected instead of the toxins; We begin by inoculating 



