Superficial bacterial pyoderma is one of the most common skin diseases of dogs. In 1976, Staphylococcus intermedius was identified as the primary pathogen. It is considered to be an opportunistic pathogen and is found within hair shafts and on hairs, skin, mucosal areas, and mucocutaneous areas of dogs. The anal area is believed to be an important carriage area. Contamination of the skin is believed to occur during grooming and pruritic behaviors. A "strain" is a clonal population in which all members are genetically identical and have the same phenotypical characteristics. It is unknown whether Staphylococcal isolates cultured from pustules have the same genotypical pattern as isolates from carriage sites. In this study, 3 pustules and 3 carriage sites were cultured from each dog with superficial bacterial pyoderma. Staphylococcal speciation and pulse-field gel electrophoresis (PFGE) were done to answer this question. Of the 246 isolates, 203 were S. intermedius, 5 were S. aureus, 15 were Staphylococcus species, and 22 were coagulase-negative staphylococcal isolates. None of the dogs had an isolate with a PFGE pattern the same as that of another dog. Pustule isolates from individual dogs were genotypically the same, and strains from pustules were genotypically the same as strains from carriage sites on the same dog. Study funded by The Ohio State University Canine Research Fund and Bayer Animal Health

COMMENTARY: The finding that each dog had its own genetically unique strains of Staphylococcus suggests that dogs are not being colonized passively from other dogs. This study did not examine bacterial isolates among dogs in the same family, and dogs in proximity to each other may have genetically similar strains. How that would affect treatment protocols is unknown. What this study did show was that strains of bacteria from pustules were the same as those found in carriage sites. This finding does not prove that the carriage sites are the source of the infection, but it does
further highlight the importance of concurrent therapy when dogs are being treated for bacterial pyoderma. Grooming to remove debris and retained hair from the coat along with extra attention to bathing of carriage sites needs special emphasis with clients. Anal pruritus leads to increased anal licking and mechanical carriage and spread of bacteria. Controlling pruritic skin disease and recurrent pyoderma is clearly important

Genotypic relatedness of staphylococcal strains isolated from pustules and carriage sites in dogs with superficial bacterial pyoderma. Pinchbeck LR, Cole LK, Hillier A, et al. Am J Vet Res 67:1337-1343, 2006.