Tick-borne diseases in dogs can be produced by a number of infectious agents including Anaplasma sps., Borrelia burgdorferi, Ehrlichia canis, Ehrlichia chaffeensis, and Ehrlichia ewingii. In an effort to understand the organism-specific infection rates in dogs, we examined over 4000 serum samples, obtained from a network of diagnostic laboratories, from dogs suspected of having a tick-borne illness. Serum samples were tested on a prototype in-clinic ELISA (IDEXX Laboratories), using genus- and species-specific markers for the presence of antibodies to the above agents. The data obtained from this evaluation are summarized below.

Of the 4000 samples tested, 46.3% had antibodies to B. burgdorferi; 11.7% to Anaplasma, while 13.2%, 0.9%, and 3.6% had antibodies to E. canis, E. chaffeensis, and E. ewingii analytes, respectively. The highest incidence of co-infection was for Anaplasma/Borrelia dual infection (21.5% of samples) followed by E. canis/E. ewingii (1.1%). The demographics of the data, despite the limitation of samples being sourced from discrete laboratory locations, reveal endemic areas of both borreliosis and anaplasmosis in the Northeast, upper Midwest, and Pacific coast regions. The data also show widespread incidence of E. canis across the country with endemic pockets of E. chaffeensis and E. ewingii.