Imidacloprid plus Moxidectin to Prevent Heartworm Infection (Dirofilaria immitis) in Ferrets

Abstract

Ferrets are susceptible to Dirofilaria immitis infection and develop a disease comparable to that in cats and dogs. Treatment options are limited, thus prevention would be a viable alternative. A study was conducted to evaluate the efficacy of a combination of 10% w/v imidacloprid plus 1.0% w/v moxidecin spot-on to prevent patent D. immitis infection in experimentally infected ferrets when administered once 30 days post-infection. Twelve ferrets were acclimated to the study facility for seven days. The ferrets were free of heartworm infection prior to the artificial infection, as demonstrated by negative test results onmicrofilarial and antigen tests. On study day −30, the twelve ferrets were artificially infected with 25 infective, thirdstage larvae of D. immitis. On study day −1, the twelve ferrets were randomised and allocated to two study groups so that each group contained six ferrets. On study day 0, the animals assigned to group 1 were treated with a combination of 10% imidacloprid / 1% moxidectin at a dose of 0.4 ml per ferret. The animals assigned to group 2 served as untreated controls. On study day 124, the ferrets in both study groups were euthanised and necropsied to determine the worm burden. Ferrets in the control group (group 2) were adequately infected with D. immitis at necropsy to allow assessment of the treatment group in this study (GM = 17.2worms). The efficacy of a combination of 10% imidacloprid / 1.0% moxidecin against artificial infections with D. immitis in ferrets was 100% when administered once, at a target dosage of 0.4 ml, 30 days post-infection. No adverse events were observed which were considered to be treatment related.