TETANUS ANTITOXIN 495 



are beneficial or not. At times exaggerated claims are made for such 

 products, and the veterinarians are very apt to make use of them, 

 regardless of whether the cases are adapted to that form of treat- 

 ment. 



" This applies especially to the bacterial vaccines, vs^hich, at the 

 present time, have gained such great popularity vi^ith the veterinary 

 profession. Polyvalent, mixed, strepto, staphylo, colon, etc., bac- 

 terins, are injected into animals at times v^ithout any basis for such 

 treatment. I do not intend to condemn any of these preparations, but 

 I desire to strongly advise veterinarians to use good judgment in the 

 selection of such preparations, since in using biological products there 

 is more or less an inclination to disregard or neglect other means of 

 treatment, vyhich would probably benefit the animals far more than a 

 useless injection of an inert product for the particular case." 



ANTITOXINS 



The two antitoxins in general use are Tetanus and Diphtheria, the 

 former only being used in veterinary practice. 



Tetanus Antitoxin. Several methods are used to produce anti- 

 toxin, the details of which vary but slightly. The first thing neces- 

 sary is an active toxin. This is produced by growing Bacillus tetanus 

 (in the preparation of tetanus antitoxin) in bouillon cultures anaero- 

 bically for from six to ten days. The culture fluid is then filtered 

 through porcelain and the germ-free filtrate is used for the inocula- 

 tion. The horse receives 5 mils as the initial dose of a toxin of 

 which 1 mil would kill 100 guinea pigs each of 350 grams weight. 

 This amount of toxin is injected along with twice the amount of 

 antitoxin required to neutralize it. In five days this dose is doubled 

 and then every five to seven days larger amounts are given. After 

 the third injection, the antitoxin is omitted. The dose is increased 

 at first slowly until appreciable amounts of antitoxin are found to be 

 present and then as rapidly as the horse can stand it, until 700 — 800 

 mils of the toxin can be injected at one time. This amount should 

 not be injected in a single place or severe local and perhaps fatal 

 tetanus may develop. This treatment should continue over several 

 months until the blood of the animal contains sufficient antitoxin. 



Antitoxin unit. The method of standardizing the antitoxin is to 

 determine its protective action on guinea pigs of standard weight (350 

 grams) when injected with a toxin of a knovsm strength. A tetanus 

 antitoxin unit is ten times the least amount of serum (from the 

 immunized horse) necessary to save the life of a 350 gram guinea 

 pig for ninety-six hours against 100 minimal lethal doses of a precipi- 

 tated toxin prepared most carefully and under standard conditions, 

 by the Hygienic Laboratory of the Public Health and Marine-Hospi- 

 tal Service. 



