Mice and rats account for the vast majority of laboratory animals worldwide, yet their welfare is often treated as secondary to experimental outcomes. Improving rodent welfare is both ethically important and scientifically beneficial.
Rodents experience pain, fear, and distress in ways closely comparable to larger mammals. Barren caging, isolation, repeated handling stress, and invasive procedures cause measurable suffering. Refinement of husbandry — providing social housing, nesting, hiding places, and appropriate handling techniques — reduces suffering substantially without compromising experimental validity. In many cases it improves it, as chronically stressed animals produce unreliable data.