Effects of flumethrin and eprinomectin in naturally infected mice with Myocoptes musculinus

Mite infestations can occur in laboratory mice and cause an undesirable immune system response and adversely affect study results. Myocoptes musculinus is a mite species that can occasionally parasitized in laboratory-housed and breeding mice. In this study, the efficacy of flumethrin and eprinomectin were compared in 30 male Balb/c mice naturally infested with M. musculinus. Balb/c mice were divided into three different groups comprising eprinomectin treated, flumethrin treated and untreated control. Eprinomectin and flumethrin applied at doses of 5 mg/kg and 1 mg/kg body weights, respectively. An equal volume of mineral oil was also applied to untreated control group. Clinical scoring was done in all groups before drug administration and on days 7, 14 and 21. Scrap samples were collected and evaluated before the study (day 0) and on days 7, 14 and 21 during the study. Each colony was also videotaped for 15 min every day to calculate the Pruritic Index (PI: scratching and gnawing acts/mouse/minute). Obtained results showed that both eprinomectin and flumethrin pour-on applications significantly decreased the number of different life stages of the parasite in the skin scrapings. Both eprinomectin and flumethrin pour-on applications were found to be effective in the treatment of M. musculinus infestation in mice. However, compared to eprinomectin applied group, slightly higher number of eggs, adult and damaged adults (P < 0.01) were observed in group treated with flumethrin at day 14 after treatment. A significant reduction in PI in eprinomectin treated group 1 day after treatment, while reduction in PI was 3 days after treatment in flumethrin treated group. Clinical scoring data indicated complete recovery in the eprinomectin treated group 21 days after treatment, while partial recovery was observed in the flumethrin treated group. As a result, it can be concluded that pour-on application of eprinomectin is more effective compared to flumethrin against natural M. musculinus infestation in mice.