Rats are the most widely used mammalian model in biomedical research, and their welfare has significant ethical implications given their demonstrated intelligence, emotional complexity, and capacity for suffering.
Laboratory rat welfare has improved significantly over recent decades, but substantial challenges remain. Social isolation - historically common in research settings - is now recognised as causing severe psychological harm to a species wired for complex social relationships. Environmental enrichment including nesting material, hiding places, and opportunities for social play substantially improves welfare without compromising most research endpoints. Pain management protocols have improved, but under-treatment of pain remains documented. The 3Rs framework provides the ethical structure for improvement, but implementation depends on institutional culture and researcher training. Non-animal alternatives continue to advance.