The 3Rs framework - Replace, Reduce, Refine - guides efforts to minimise animal suffering in scientific research. Progress is significant but replacement remains elusive in many areas.
Animals used in research face acute and chronic welfare challenges. Pain and distress from procedures, confinement in laboratory environments, and social isolation for social species all represent welfare costs. The 3Rs framework requires researchers to replace animals with alternatives where possible, reduce numbers when replacement is not possible, and refine procedures to minimise suffering. Progress on replacement is variable - alternatives for some toxicity tests are well-developed, but complex disease models are harder to replace. Severity classifications attempt to quantify suffering and are used in regulatory oversight.