Laboratory mice and rats are the most numerous research animals globally, and applying the 3Rs framework of Replacement, Reduction and Refinement can dramatically improve their welfare.
The sheer scale of mouse and rat use in research — tens of millions annually worldwide — means that even modest welfare improvements translate into enormous aggregate reductions in suffering. Basic refinements such as providing nesting material, maintaining appropriate group sizes and using less aversive handling techniques are low-cost and well-evidenced. More substantive refinements involve replacing stressful behavioural tests with less distressing alternatives and adopting in vivo imaging that reduces terminal sacrifice. Institutional animal care committees and the 3Rs infrastructure have driven progress, but implementation is uneven and welfare monitoring during experiments remains inadequate in many facilities.