Efficacy of rifampicin in the treatment of experimental acute canine monocytic ehrlichiosis

Objectives: To assess the efficacy of rifampicin in achieving clinical and haematological recovery and clearing infection in dogs with experimentally induced acute monocytic ehrlichiosis. Methods: Five Ehrlichia canis-infected Beagle dogs were treated with rifampicin (10 mg/kg/24 h orally for 3 weeks), nine E. canis-infected dogs received no treatment (infected untreated dogs) and two dogs served as uninfected controls. Clinical score, platelet counts, immunofluorescent antibody titres and PCR detection of E. canis-specific DNA in blood, bone marrow and spleen aspirates were evaluated on post-inoculation days 21 (start of rifampicin), 42 (end of rifampicin) and 98 (end of the study). Results: By day 21 post-inoculation, all infected dogs became clinically ill and thrombocytopenic, seroconverted and were PCR positive in at least one tissue. Clinical scores and antibody titres did not differ between the treated and infected untreated dogs throughout the study. The rifampicin-treated dogs experienced a