Levamisole as a microfilaricidal agent in the control of canine dirofilariasis.

The effectiveness of levamisole hydrochloride as a microfilaricidal agent when used 3 weeks after thiacetarsamide sodium therapy for canine dirofilariasis, was studied in 6 experimental dogs and 20 clinical cases. The drug, when administered orally in gelatine capsules daily, cleared microfilariae from the circulation in the experimental dogs in 7 to 11 days. A dose rate of 10mg/kg appeared as effective as 15mg/kg. In the clinical group 70% of dogs had zero microfilarial counts after 4 to 8 doses at 10mg/kg daily. Vomiting, diarrhoea and inappetence were observed in some animals, but were not a significant problem. Elevations in plasma GPT and AP levels were recorded during the administration of levamisole in some dogs while GOT levels rose in 1 dog only. Urea and creatinine levels were unaffected in all dogs. The only haematological parameter affected was the eosinophil count which rose during levamisole administration. All levamisole-treated animals, were successfully commenced on daily DEC, as a prophylactic measure, while an anaphylactic-type reaction occurred when this drug was administered to 1 of the 2 control animals.