Natural infections with Borrelia spirochetes in two dogs from Florida.

Spirochetemia is a rarely reported observation in dogs. We describe the clinical, hematologic, and immunodiagnostic features of two spirochetemic dogs from northern Florida and the subsequent isolation and preliminary characterization of a Borrelia species from one dog in which culture of a sample for spirochetes was attempted. Results of polyacrylamide gel electrophoresis, monoclonal antibody testing, and PCR analysis indicate that the Florida isolate is not Borrelia burgdorferi, the only other member of the genus that has been isolated in Florida. Our findings also indicate that a member of the genus Borrelia potentially causes disease in dogs in Florida and that serologic cross-reactivity of the Florida canine Borrelia isolate with B. burgdorferi probably contributes to the inaccurate diagnosis of canine Lyme disease in the region.