Refinement — reducing pain and suffering in laboratory animals — is the most immediately impactful of the Three Rs principles and applies to all research using animals.
Refinement is often the most immediately achievable welfare improvement in animal research. While replacement (using alternatives) and reduction (using fewer animals) require longer-term systemic changes, refinements can be implemented within existing protocols. Providing appropriate housing enrichment, using the least aversive procedure that achieves scientific objectives, and applying adequate analgesia for painful procedures are all refinement opportunities. Humane endpoints — the pre-agreed point at which animals are euthanised to prevent unnecessary suffering — are a critical refinement that requires explicit planning.