Fig. 1
Mean microfilarial counts for dogs. All treatments started on day 0. Group 1 dogs (short-treatment regimen) were administered doxycycline orally at 10 mg/kg sid for 30 days plus ivermectin orally (minimum dose, 6 mcg/kg) on days 0 and 30. Group 2 dogs (long-treatment regimen) were administered doxycycline orally at 10 mg/kg sid until individual dogs became amicrofilaremic (days 72–98) and ivermectin every 2 weeks until individual dogs became amicrofilaremic (6–7 doses). Group 3 dogs were the untreated control. Group 1 and 2 dogs became microfilaria-negative on days 239 and 97, respectively, and remained negative through day 647. Significant differences in mf counts were observed between both treated Group 1 and treated Group 2 and the control (Group 3) (Wilcoxon matched-pairs signed-rank test, P < 0.0001 for each). No significant difference was observed between treated Groups 1 and 2 (Wilcoxon matched-pairs signed-rank test, P = 0.54). There was no significant difference in time to mf clearance between treated Groups 1 and 2, with a median time to clearance of 83.5 and 90 days, respectively (χ2 = 0.066, degrees of freedom [df] = 1, P = 0.80)