Haemaphysalis concinna (Acari: Ixodida): Persistent efficacy of doramectin in rabbits under laboratory conditions

In the present study, the persistent efficacy of doramectin (DOR) in rabbits infested by Haemaphysalis concinna was observed. DOR (200 µg/kg) was administered once to infested rabbits by subcutaneous injection. A total of 15 rabbits were allocated to three groups, which were observed for efficacy. On days 1–7, 8–14, 15–21 and 22–28 post-inoculation, the percent reduction of tick larvae in DOR treated rabbits was 100.0, 100.0, 86.7 and 61.7%, respectively; the percent reduction of nymphs was 100.0, 90.0, 75.0 and 65.0%, respectively; and the percent reduction of adults was 85.0, 65.0, 55.0 and 55.0%, respectively. In comparison, in untreated rabbits at the same time points (control group), the percent reduction of larvae was 5.0, 3.3, 5.0 and 5.0%, respectively, and there was no reduction of nymphs and adults in the untreated rabbits.