Treatment of Dirofilaria repens microfilariaemia with a combination of doxycycline hyclate and ivermectin

Dirofilaria repens is one of the most widespread mosquito-borne filarioid responsible for infestations in dogs, usually characterized by nodules and other skin lesions. Additionally, the zoonotic potential of this nematode is of public health concern, given that D. repens has been often associated to human dirofilariosis in the Old World. In the present study, the therapeutic efficacy against D. repens microfilariae of a protocol based on doxycycline hyclate (Ronaxan®, Merial), 10mg/kg every day for 30 days, and ivermectin (Cardotek 30®, Merial), 6μg/kg every 15 days for 6 months, was preliminarily investigated in two naturally infested dogs. Blood samples were collected every 30 days during 6 months of treatment and examined by a Knott's modified test and a duplex real-time PCR. The results here presented indicate that this therapeutic protocol, applied monthly, could be effective for treating microfilariaemia in dogs affected by subcutaneous dirofilariosis.