STREPTOCOCCAL TOXIC SHOCK SYNDROME IN DOGS

Objective-To determine the clinical, pathologic, and bacteriologic fin dings in dogs that developed severe invasive infections with group G s treptococci (GGS) over a 6-month period in southern Ontario. Design-Pr ospective case series. Animals-7 dogs in southern Ontario with severe streptococcal infection during a 6-month period. Procedure-Using pulse d-field gel electrophoresis, molecular typing of streptococcal isolate s was performed. Isolates were examined for the M protein gene emm1.0, pyrogenic exotoxin genes speA, speB, speF, hyaluronic acid synthase g enes hasA, hasB, and for C5a peptidase gene scpA by use of DNA probes or polymerase chain reaction. Results-3 dogs with streptococcal shock without necrotizing fasciitis died or were euthanatized within 48 hour s of admission, whereas 4 dogs with streptococcal shock and necrotizin g fasciitis survived following surgical debridement, supportive medica l treatment, and treatment with antibiotics. Of the 6 Lancefield group G streptococcal isolates available for characterization, 5 were Strep tococcus canis and 1 had characteristics of group G streptococcal stra ins of human origin. Results of molecular typing indicated that isolat es were unrelated to each other. Examination of the canine isolates fo r putative virulence genes found in human group A streptococci resulte d in identification of the the emm1.0 gene only in 1 of the isolates. The canine isolates otherwise lacked virulence genes associated with h uman group A streptococcal toxic shock infections. Clinical Implicatio ns-The development of severe invasive infection in dogs resulting from GGS indicates that a virulent form of GGS has developed in southern O ntario.