Because no flea-control products are approved for rabbits, which are susceptible to Ctenocephalides felis or C canis infestation, treatments are extrapolated from other species. On day 0 of this study, 2 groups of juvenile rabbits (n = 6/group) were treated with topical selamectin at either 10 or 20 mg/kg; a third group of rabbits (n = 6) was used as the control. On days –1, 7, and 14, each rabbit was infested with 50 laboratory-raised unfed fleas. All rabbits were flea-combed on days 2, 9, and 16; each combing was approximately 48 hours after infestation. On day 2, the efficacy against fleas was 91.3% and 97.1% for the 10 mg/kg and 20 mg/kg treatment groups, respectively. Over the course of the 28-day study, efficacy against fleas dramatically decreased as early as 9 days’ postapplication. By day 16, efficacy was 6.6% and 13.5% in the 10 and 20 mg/kg groups, respectively. No adverse effects were noted. Pharmacokinetic studies showed that selamectin has a short half-life compared with use in dogs and cats. The recommended dose based on these findings was 20 mg/kg q7day to control fleas.

Commentary
Many clinicians have used selamectin at a dose of about 6 mg/kg, usually repeated q2week, to treat mite and flea infestation in rabbits, rodents, and other pocket pets. For certain infections (eg, Psoroptes cuniculi [rabbit ear mite]), single-dose applications of selamectin can be sufficient to effect cure. For flea treatment in rabbits, anecdotal evidence has suggested redosing at monthly intervals.1 There has been little guidance as to the duration of efficacy of selamectin in exotic pets. This small study suggested that flea-infested rabbits may need higher doses of selamectin more frequently.—Dominique Keller, DVM

Source
Pharmacokinetics, efficacy, and adverse effects of selamectin following topical administration in flea-infested rabbits. Carpenter JW, Dryden MW, KuKanich B. AM J VET RES 73:562-566, 2012.

1. Efficacy and safety of selamectin (Stronghold/Revolution) used off-label in exotic pets. Fisher M, Beck W, Hutchinson MJ. Int J Appl Res Vet Med 5:87-96, 2007.