More Enrichment Makes for Healthier Rodents

A recent meta-analysis published in the journal Applied Animal Behaviour Science (Cait et al., 2024) found that the more types of resources (i.e., “enrichment”) rodents receive, the better their health. A previous study by these authors (see AWI Quarterly, spring 2022) found that rats and mice housed in conventional laboratory cages experience chronic stress, which causes them to have higher morbidity (disease severity) and mortality than rodents who live in “well-resourced” cages. The new study aimed to dig further into the relationship between enrichment and health by determining whether the number of resource types mattered.

The authors explored the impact of providing one to five types of additional resources (the maximum number they could assess based on the available studies) compared to conventional housing standards. The resources included were those known to meet a particular rodent behavioral or physiological need: additional space, increased environmental complexity, nesting materials, shelters, and wheels. 

The study found a positive linear relationship between the number of resource types and rodent health, with no leveling off even at five resource types—suggesting that rodents would continue to benefit even if more than five types of enrichment were added. It also supports the authors’ previous findings that rodents in conventional housing have greater morbidity than those in better-resourced housing, which has implications both for rodent welfare and for the scientific research conducted with them. The authors recommend setting more ambitious housing standards to improve the welfare of the millions of rodents used in laboratory research.

Program Terms: Animals in Laboratories

AWI Quarterly Terms: Feature Article