As many Ehrlichi spp. infect dogs, serologic testing can be nonspecific and may not be clinically relevant.

The E. canis genogroup consists of E. canis, E. chaffeensis, and E. ewingii. Exposure to any of these organisms will result in E. canis seropositivity. Low antibody titers (< 1:160) may not necessarily indicate infection, as 50% of dogs with low titers are reported to be negative on Western blot testing for E. canis and E. chaffeensis. Thus, low titers need to be interpreted cautiously.

E. platys has been associated with cyclic thrombocytopenia in dogs, but not with other clinical illness. In contrast, E. equi is becoming more common as a cause of canine granulocytic ehrlichiosis in areas where Ixodes spp. ticks are more prevalent. E. risticii has also been shown to infect dogs.