VETERINARY MEDICINE. 781 



ments was to determine tlie smallest amount of antitoxin which is necessary to 

 protect a susceptible horse against a fatal infection with tetanus. 



Before undertaking the experiments on horses tests were made on guinea 

 pigs, and in these it was found that from 0.25 to 0.5 cc. of washed tetanus cul- 

 tures (freed from the toxin), mixed with a very small quantity of sterilized 

 dirt, was sufficient to produce the disease. Without the dirt the disease could 

 not be made to develop. 



In the actual investigation 8 horses, which were In good health and fair 

 condition, were used. During the tests they gained in weight. In order to 

 conform to the conditions prevailing in nature, the part to be infected was first 

 bruised by a severe blow with a blunt instrument, or by pinching the parts. 

 The material used for inoculating the horses was a culture heated to 75° C. 

 for 45 minutes in order to eliminate the toxin. Three cc. of the culture, to 

 which was added a small quantity of dirt, was given to each of the 8 animals. 

 Following the virus injection, 7 of the animals received an injection of antitoxin. 

 Forty-eight hours after infection injections were again given to 2 animals, 68 

 hours after injection to 1 animal, 72 hours after injection to 2 animals, and 

 96 hours after injection to 2 animals. The amount of antitoxin given varied 

 from 250 to 700 units. The eighth animal, which received no antitoxin, suc- 

 cumbed 9 days after passing through a cycle of symptoms classical for tetanus. 

 From the results it is "evident that a considerably smaller dosage of antitoxin 

 could be employed for preventive purposes in horses than has been recommended 

 for man. Only in 2 instances did localized tetanus develop susbequently to the 

 antitoxin injection, and even these animals recovered. In these cases 250 and 

 400 units of antitoxin were injected, respectively. In consideration of the fact 

 that all the horses used in these tests were quite aged and accordingly not 

 nearly so susceptible as young animals, a somewhat larger amount of antitoxin 

 would be necessary to prevent absolutely the development of tetanus in the latter 

 class of animals. Accordingly, 500 units would seem to be sufficient for the 

 prevention of tetanus in horses of any age. Since the cost of this product could 

 be reduced considerably by employing this smaller quantity of antitoxin as com- 

 pared with the former preventive dose of 1,500 units, its application in practice 

 will probably become more general when the standard of 500 units is adopted. 



"It will be observed that in these experiments the antitoxin was employed 

 at different periods subsequent to the infection, and the results obtained indicate 

 that the administration of the antitoxin even 96 hours after the infection will 

 prevent the development of the disease. This is of considerable practical im- 

 portance, inasmuch as frequently the veterinarian is called to attend an in- 

 jured animal only after a considerable time has elapsed following the injury." 

 When considering tetanus antitoxin as a curative agent, it is pointed out that 

 on the whole the results are unsatisfactory, and the cost is very high. 



During 1911 a horse, which was previously used for hyperimmunization work 

 with swamp fever, developed a rapidly progressing attack of tetanus. As anti- 

 toxin was not readily available, it was given subcutaneous injections of 20 cc. 

 of a saturated solution of magnesium sulphate in each side of the neck. " The 

 treatment was continued twice daily from September 27 to October 8, and then 

 once daily from October 9 to October 19, with the result that complete recovery 

 took place. In about li hours after each of the early injections, the animal 

 would show marked relaxation of the muscles, which seemed to indicate that 

 the sulphate reduces the tonic spasms of the muscles rather than actually 

 neutralizing the toxin. In this manner the animal is given an opportunity to 

 form its own antitoxin, while its strength is being supported by the reduction 

 of excitability and the ability to take some nourishment. In consideration of 

 the severity of this case and the splendid results obtained from the treatment 



