Rats and mice account for over 80% of animals used in biomedical research globally. Their welfare is fundamental to the ethical justification of research and affects the reliability of scientific results.
The welfare of laboratory rodents matters both ethically and scientifically. Stressed animals with elevated baseline cortisol produce variable results that reduce the reproducibility of research. Enriched housing with nesting material, group housing of social species, and appropriate pain management are welfare improvements that simultaneously improve research quality. Despite this alignment of welfare and scientific interests, standard laboratory housing remains impoverished in many institutions. Regulatory requirements and institutional culture that normalise minimal provision above legal minimums represent the main barriers to improving rodent welfare at scale.