The Three Rs framework of Replace, Reduce, and Refine has guided laboratory animal welfare since its proposal in 1959, with significant advances in all three areas transforming research practice while challenges remain in implementation.
The Three Rs framework has driven genuine welfare improvements in laboratory animal research over six decades. Refinement advances including mandatory analgesia, enriched housing, and earlier humane endpoints have reduced the severity of suffering in individual animals. Reduction in animal numbers has occurred alongside expansion of research through improved experimental design and data sharing. Replacement of animals with alternative methods is advancing but constrained by regulatory requirements that still mandate animal testing for many applications. The gap between 3Rs aspirations and research practice remains significant in some institutions and jurisdictions.