Dietary Fenbendazole Treatment Does Not Impair Skilled Forelimb Motor Function in C57BL/6J Mice.

Fenbendazole (FBZ) treatment for pinworm infections is generally safe and effective but not without concern for potential research complications in its application to laboratory animal colonies. Previously, dietary FBZ was found to impair motor performance in C57BL/6N mice, an effect that endured at least 2 wk posttreatment. These findings raised the possibility that FBZ treatment would complicate our own research on poststroke motor function in C57BL/6J mice. Here we present the results of a study that tested this possibility in the context of facility-wide FBZ treatment based on repeated measures in a skilled reaching task that is extremely sensitive to forelimb motor impairments. Mice of both sexes that were proficient in the reaching task were measured in their performance of the task in each of the 4 wk preceding, 7 wk during, and 2 wk after dietary FBZ treatment that alternated weekly between therapeutic and subtherapeutic doses. There was no indication of a notable decrement or other change in reaching performance during or after FBZ treatment (mean ± SE percent success before, during, and after treatment = 57 ± 2, 53 ± 2, and 60 ± 2; n = 20). Performance stability in FBZ-treated mice was similar to that of untreated mice. These results are significant for revealing a lack of noticeable influence of FBZ on a commonly used measure of motor function in a widely used mouse strain. The difference in FBZ effects relative to the prior study could reflect substrain-dependency (6N compared with 6J) and/or differences in motor behavioral measures.