Experimental Clostridial Infections in Dogs

Abstract

The work presented in this paper represents a chronological summary of approximately six years' experience with clostridial infections in 1,638 dogs. The objectives of the study were to determine the most practical and effective means applicable under conditions of war which would (1) prevent the occurrence of gas gangrene and (2) combat the disease once it had become established. To accomplish the objectives as stated, the scope of the work was of sufficient magnitude to encompass a study of gas gangrene as produced by several of the most common clostridial organisms both in individual pure culture and mixed culture inocula. The efficacy of a given prophylactic2 or therapeutic3 agent was then measured against the virulence of a given infectious agent or agents in the dog with the avoidance of unnecessarily complicating and variable factors. The design of the experiments was such as to minimize trauma and to exclude anesthesia and surgical technics. The degree and extent of interest and co-operation in the program are denoted by the accompanying list of participating groups and organizations. We are indebted especially to Dr. M. A. Logan and his associate Dr. A. A. Tytell of the University of Cincinnati, who prepared many of the preliminary toxoid preparations and who determined all of the alpha antitoxin titre levels on the dogs utilized in the toxoid experiments. Experimental Material and Procedures Infectious Agents: The infectious agents used in producing the standardized clostridial infections in dogs are listed in Table I. Since the inocula were prepared from media containing chopped meat, the number of organisms per inoculum can be given only in approximation. No attempt was made to differentiate between the vegetative organisms and the readily germinating spores in the various inocula. However, the inocula so used, regardless of the clostridial species, were uniform in respect to the severity of the infections and to the fatalities in the control animals over the several years in which the experiments were carried out. This consistency in the pathogenicity of the infectious agents is substantiated by a survey of fatalities in the control animals. In the Cl. welchii control animals there was an 86.8 per cent fatality in 129 control dogs in the period from 1941 to 1944. The 25 Cl. welchii controls of 1942 showed an 88.0 per cent fatality with an average survival time of 39.5 hours. The 30 Cl. welchii controls of 1944 showed a 90.0 per cent fatality with an average survival time of 49.2 hours. This agreement in fatalities was typical of the results obtained with the other clostridial infectious agents used, either singly or in combination (Table II.) Douglas' medium (1) containing chopped heart and plugged with vaseline was used both for storage of the clostridia and for cultivation of the infectious inocula.