Rats are the second most commonly used laboratory mammals and have complex social and cognitive needs that require specific enrichment to meet welfare standards.
Laboratory rat welfare has improved substantially through the development of validated behavioral and facial assessment tools, growing recognition of their social complexity, and refinement of group housing practices. However, many research facilities still house rats in small, understimulating cages that fail to meet their behavioral needs. Providing nesting material, climbing structures, hiding places, and compatible social companions at low cost addresses the most significant welfare gaps. Institutional animal care programs that apply the 3Rs rigorously and use welfare assessments beyond simple health checks achieve genuinely better rat welfare outcomes.