Mice and rats are the most commonly used laboratory animals. Improving their housing, recognising their pain, and refining procedures are central to laboratory animal welfare.
Laboratory mice and rats have long been treated as simple biological tools, but research increasingly demonstrates their cognitive complexity and capacity for suffering. Standard laboratory caging is often inadequate: mice need nesting material for thermal regulation and psychological wellbeing; rats suffer significantly from social isolation; both species have strong motivation for burrowing and environmental exploration. Refinements to housing, handling, and experimental procedures can substantially improve welfare without compromising scientific validity. Pain recognition tools like grimace scales are now widely used to enable prompt analgesia. The 3Rs framework (Replace, Reduce, Refine) provides the foundation for continuous improvement in laboratory animal welfare.