458 PRINCIPLES OF VETERINARY SURGERY 



have also similar properties, but are not as easily managed 

 as iodine, nor do they give any better results. 



SEROTHERAPY. — Animals immunized against tetanus 

 may receive large doses of tetanic toxin. They are refractory 

 to the poison. At first it was thought that the property of 

 destroying the efifects of the poison was due to a substance 

 existing in the tissues of the vaccinated animal (antitoxin) 

 that possessed the power of annihilating the toxin when 

 brought into contact with it. The hypothesis was advanced 

 by Behring and Kitasato, who based their conclusions on 

 the following experiment : 



If the blood serum of an animal vaccinated against teta- 

 nus is mixed with toxin, the mixture may be safely injected 

 into the most sensitive animals. The serum of vaccinated 

 animals seems to neutralize the tetanic toxin as an acid neu- 

 tralizes an alkali, and may be injected into different regions 

 with impunity when mixed with fatal doses of the pure toxin. 

 Furthermore, the injection of toxin is without efifect if pre- 

 ceded a few hours by an injection of the antitoxic serum. 

 It will also prevent efifects from inoculations of tetanus spores 

 impregnated with toxins. 



These efifects are the basis of serotherapy. The blood se- 

 rum of vaccinated animals is immunizing. It may be used as 

 a vaccine and as such will immediately confer immunity. The 

 discovery of the vaccinating properties of the vaccinated 

 blood was confirmed by Tizzoni and Cattani in 1891, but 

 they state that the serum cannot cure tetanus once developed. 

 In 1892, Vaillard showed that the blood of a hen, an animal 

 slow in contracting tetanus, does not neutralize the toxin, 

 but becomes antitoxic about twenty days after an injection of 

 filtered culture into the peritoneum. He also established 

 that- the bacillus may grow and secrete toxin in the serum 

 of refractory animals; that it multiplied in the living tissues 

 of vaccinated animals and that it is not attenuated by the pro- 



