Treatment of Crenosoma vulpis Infection in Two Silver Foxes (Vulpes vulpes) with Ivermectin

A male and female silver fox (Vulpes vulpes) were diagnosed with naturally acquired infections of the lungworm Crenosoma vulpis at the Cherry Brook Zoo in St. John, New Brunswick, Canada. The main clinical sign was a chronic cough. Crenosomiasis was diagnosed by fecal examination using the Baermann technique. The foxes were treated with a subcutaneous injection of ivermectin (200 μg/kg). Clinical signs resolved, and fecal exams were negative at 3 and 6 wk posttreatment. No adverse reactions to the drug were observed. This is the first reported use of ivermectin against C. vulpis infection in canids. Due to the small number of animals involved and the absence of posttreatment necropsy/worm recovery data, this indication of efficacy must be viewed as circumstantial until further testing.