UBC Theses and Dissertations

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UBC Theses and Dissertations

Environmental enrichment for rats and mice housed in laboratories Ratuski, Anna Selene


There is mounting evidence that current laboratory housing practices negatively impact rodent welfare. Environmental enrichment is generally recommended to improve housing, but definitions and applications of enrichment vary widely. The aims of this thesis were to explore the concept of environmental enrichment and to test applied strategies to improve housing for rodents in laboratories. In Chapter 2, I conducted a metareview of environmental enrichment for rats and mice. Authors most often supported the provision of social companions, nesting material, shelters, foraging opportunities, and larger environments (for rats). However, authors often described perceived risks or requirements of enrichment, which represent potential barriers to implementing enrichment. In Chapter 3, I investigated how the addition of an upper loft area affects the behaviour of rat dams housed in laboratory cages with their pups. My results suggest that dams use lofts as an area to get away from pups, allowing for more natural weaning and improved emotional states. In Chapter 4, I conducted a similar experiment with mouse dams housed with their pups in shoebox cages. I found that elevated tunnels were not universally effective at altering dam behaviour or welfare, and outcomes differed according to genetic strains. In Chapter 5, I gave shoebox-housed mice access to playpens on a regular basis and tested whether this was a positive experience for them. Mice showed increased anticipatory behaviour and speed of entry, indicating that playpen access was rewarding; they also engaged in a range of natural behaviours while in the playpens. In Chapter 6, I assessed anxiety, aggression, and stereotypic behaviour to determine how regular playpen access impacted mouse welfare. Playpen access improved some welfare measures, but outcomes tended to vary according to genetic strain. Collectively, this work suggests that there are welfare benefits to housing rodents with resources that allow for more diverse or motivated behaviour, but not all strategies will be equally impactful for welfare. More specific and value-neutral terms should be used to describe elements of an environment and how they are believed to affect the welfare of the animals.

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