Serologic evidence of canine and equine ehrlichiosis in northeastern United States.

In a retrospective study, indirect fluorescent-antibody staining methods were used to detect immunoglobulins to Ehrlichia canis and Ehrlichia risticii in canine and equine sera that had originally been analyzed for antibodies to Borrelia burgdorferi. Analyses of 60 dog serum specimens collected in Connecticut and New York State during 1986 revealed antibodies to E. canis in 7 (11.7%) specimens; titration endpoints ranged from 1:40 to 1:320. Three of these dogs had anemia. Of the 187 equine serum specimens obtained in Connecticut during 1985 and analyzed by indirect fluorescent-antibody staining methods, 17 (9.1%) contained antibodies to E. risticii. Maximal antibody titers of 1:1,280 were recorded for serum specimens collected from three equids during May and July. We conclude that canine and equine ehrlichiosis coexist with Lyme borreliosis in Connecticut and the lower Hudson River Valley of New York State.