Rats are among the most widely used laboratory animals. Understanding their social and behavioral needs reveals how current standard housing falls short of welfare best practice.
Laboratory rat welfare has improved significantly through application of the 3Rs and growing understanding of rat cognition and social needs. However, gaps between best practice and common practice remain substantial. Social housing is well-evidenced as beneficial and is increasingly mandated, but implementation varies. Enrichment provision remains inconsistent despite strong evidence that nesting material, shelter, and foraging opportunities reduce chronic stress without compromising experimental validity. The grimace scale and other validated behavioral pain measures enable better refinement of analgesia protocols. The welfare challenge in rat research is not primarily about eliminating use but about closing the gap between what welfare science shows is possible and what most facilities actually provide. This requires institutional commitment, training, and willingness to invest in animal welfare infrastructure.