Characterization of the subclinical phase of ehrlichiosis in dogs.

Prevalence of subclinical Ehrlichia canis infection in a Mississippi kennel was 53%. Most of the dogs probably had been infected for 4 or 5 years. The subclinical phase of the infection was characterized by high antibody titers to E canis (9 of 10 dogs with titers of 1:5, 120), hyperglobulinemia (9 of 10 dogs), thrombocytopenia (5 of 10), absolute lymphocytosis (4 of 10), and absolute neutropenia (3 of 10). The dogs had normal PCV, serum albumin concentrations, and urine protein excretion. Findings indicated that a high percentage of dogs in an enzootic area may develop subclinical ehrlichiosis that may last several years. Despite persistent antigenic stimulation, dogs subclinically infected for a prolonged time did not develop clinically apparent glomerular disease. However, evaluating dogs for antibody titers against E canis is recommended in endemic areas because subclinically infected dogs eventually may develop severe chronic disease, which may be less responsive to therapy.