Use of Selamectin and Moxidectin in the Treatment of Mouse Fur Mites

A breeding colony consisting of 250 different strains of mice was treated with the topical acaricide selamectin for the mouse fur mite Myocoptes musculinus, with no apparent ill effect, suggesting that this drug is safe for use in mice. To further evaluate their efficacy in treating Myocoptes spp., we compared selamectin with another acaricide, moxidectin, in a controlled manner. Infested mice were treated with selamectin or moxidectin at the time of cage change, and a subset of mice was retreated 10 d later. Mice underwent routine cellophane tape examination of the pelage for 1 y. Although no adult mites were found in any group at 1 mo after treatment, egg casings were found in the selamectin treatment group as late as 6 mo after treatment, prompting concern about its effectiveness. Moxidectin used in combination with cage changing was effective in eradicating mites, with mice negative for traces of mites on cellophane tape examination of the pelage from months 2 through 12 after treatment.