The effect of ivermectin on some haematological indices in rabbits: influence of vitamin K treatment.

1. Rabbits were treated with the antiparasitic drug ivermectin at subcutaneous doses of 0.2, 1 and 2.5 mg/kg and blood collected weekly for 4 weeks thereafter for measuring some blood parameters. At a dose of 0.2 or 1 mg/kg the drug had no significant effect on any of the parameters measured. At a dose of 2.5 mg/kg, the drug reduced significantly the erythrocyte counts, haemoglobin concentration, haematocrit, mean corpuscular haemoglobin concentration and mean corpuscular haemoglobin on weeks 1, 2, 3 and 4. Platelet counts were not significantly affected. 2. In another trial, ivermectin was injected subcutaneously at a dose of 2.5 mg/kg, after pre-treatment with either saline or vitamin K (30 micrograms/kg for 30 days), and prothrombin time, bleeding time and platelet counts measured at weekly intervals for 4 weeks. Bleeding time and thrombin time were significantly increased 1 week after treatment, and remained higher than the control for 4 weeks.