Rodent Welfare in Scientific Research

Mice and rats account for approximately 80% of all animals used in scientific research worldwide, making their welfare the most numerically significant issue in laboratory animal science, with ongoing refinement improving conditions substantially.

Key Facts

An estimated 3.8 million procedures were performed on laboratory animals in the UK in 2022, with mice accounting for the majority
Laboratory mice and rats are social animals that suffer in isolation, yet single housing is still used in some experimental designs despite welfare concerns
Nesting material provision is a basic welfare need for laboratory mice that is absent from standard minimal housing in many facilities
The grimace scale validated for mice and rats enables reliable pain scoring by trained observers without requiring complex equipment
Refinement of experimental procedures — including improved anaesthesia, analgesia, and technique — can substantially reduce pain and distress during procedures
Home Office Animals (Scientific Procedures) Act 1986 requires project and personal licence holders to demonstrate how they will apply the 3Rs
Tunnel handling — using tubes rather than scruffing to pick up mice — reduces fear and stress and is supported by the NC3Rs as a refinement

Welfare Considerations

Rodent welfare in research is numerically the most significant laboratory animal welfare issue: more mice and rats experience procedures in a single year than all other laboratory species combined by a large margin. Progress has been real and substantial — welfare codes, environmental enrichment requirements, and pain management protocols are far better than 30 years ago. Yet gaps remain: isolation housing is still justified experimentally in ways that create chronic social deprivation, pain management for post-procedural pain remains inconsistently applied, and environmental enrichment provision varies widely between institutions. The NC3Rs plays a critical role in identifying and promoting refinements that reduce welfare harm while maintaining scientific quality, and its evidence base should be the foundation of institutional welfare standards.

What You Can Do

Support NC3Rs funding and research that identifies welfare refinements applicable across the research sector
Advocate for mandatory welfare outcome reporting by research institutions including pain scores and refinement implementation data
Engage with research institutions about their 3Rs committee function and how welfare refinements are communicated to all researchers
Choose research institution collaborators and suppliers who demonstrate strong welfare committee oversight and published refinement commitments