Garcia, T., Brown, C., Margolies, D. et al. 2021. Grinding on a last nerve: Attempting to curb food grinding in mice. Laboratory Animal Science Professional 9(6) (November/December), 34-36.

Food grinding, or chewing food without ingestion, is a topic of interest in the laboratory animal community. In addition to increased effort needed to deal with this excess waste and provide suitable microenvironment for animals, ort production in the captive setting is thought to be an abnormal behavior. Grinding behavior in rodents may be stereotypic or compulsive, stemming from lack of stimulation or may have a genetic component. Previous experiments have shown that when enrichment is provided, specifically enrichment that encourages gnawing and food manipulation, ort production decreased. Therefore, we hypothesized that alternative or additional enrichment to what was provided as standard would reduce grinding. We compared four different enrichment strategies to examine whether or not a decrease in grinding among “known grinders” could be achieved and if such strategies prevented the development of grinding behavior in cages that did not previously exhibit grinding. None of the enrichment strategies tested significantly or consistently reduced the grinding behaviors over the seven-week period of observation among known grinders. Interestingly, most enrichment methods resulted in a downward trend in grinding behavior in the shorter term (for the first ~4 wk the new enrichment was introduced), but the effect on grinding was not sustained in the longer term (>4 wk following introduction). The standard enrichment group with seeds appeared to prevent non-grinders from developing any grinding behaviors whereas for all other non-grinders there was some variation week to week in grinding behavior regardless of enrichment provided with some non-grinders seemingly developing grinding behavior towards the end of the observation period. Novel and pragmatic strategies should continue to be explored and evaluated to help manage cases of grinding when strain swapping is not practical such as with most experimental mice.

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