Comparative study of doxycycline and rifampin therapeutic effects in subclinical phase of canine monocytic ehrlichiosis

A double-blind randomized controlled trial was designed for a 6-month period to compare the efficacy of rifampin versus doxycycline during the subclinical phase of canine monocytic ehrlichiosis. Ten naturally Ehrlichia canis-infected dogs with anti-E. canis immunofluorescent antibodies ranging 1/80 to 1/1,280 were divided in two therapeutic groups. The first treatment group was scheduled by prescription of 10 mg/kg/d doxycycline for 28 days. The second group treated with rifampin 15 mg/kg every 12 h for 1 week. All treated dogs were examined periodically during the 6-month period posttreatment. Alterations in anti-E. canis immunofluorescent antibodies and clinicopathologic parameters were compared before and after treatment to evaluate the efficacy of therapeutic regimens. According to the initial antibody titer, no significant difference was observed in any of the five cases in each group. A substantial main effect of time on mean PCV, thrombocyte and erythrocyte count, and gradual resolution of hyperglobulinemia was significantly observed in all treated animals (p < 0.05), whereas no significant difference was noticed between studied protocols (p > 0.05). Similar clinicopathologic response was observed in both treated groups; thus, it was concluded that rifampin and doxycycline are equally effective for treatment of canine monocytic ehrlichiosis.