Evaluation of methods to diagnose Clostridium perfringens-associated diarrhea in dogs

Objective-To assess the prevalence of Clostridium perfringens enterotoxin i n feces of dogs with and without diarrhea, and to compare the use of microb ial cultures from fecal specimens and evaluation of stained fecal smears fo r endospores with the presence of enterotoxin as tools for diagnosing C per fringens-associated diarrhea. Design-Prospective study. Animals-144 dogs representing hospitalized dogs with (n = 41) or without (5 0) diarrhea, and clinically normal dogs treated as outpatients (53). Procedure-Fresh fecal specimens from ail dogs were examined as Gram-stained fecal smears to determine numbers of Gram-positive spore-forming rods/100X objective field. Enterotoxin was assayed directly by use of a reverse pass ive latex agglutination assay. Fecal specimens were plated directly to prer educed egg yolk agar plates and incubated overnight at 37 C in an anaerobic chamber. At 24 hours, up to 3 lecithinase-positive colonies were subcultur ed to Brucella blood agar to evaluate for double zone hemolysis. Colonies w ith double zone hemolysis were tested for aerotolerance and Gram-stained. Results-A significant difference was not detected among groups with respect to the presence of C perfringens as determined by culture, the presence of endospores, and the reaction patterns of fecal enterotoxin assays. An asso ciation was not found between number of endospores and the presence of feca l enterotoxin. Clinical Implications-The presence of C perfringens enterotoxin in feces of dogs, as detected by the latex agglutination assay used in this study, cor relates poorly with the number of fecal endospores, regardless of the dog's clinical status.