Rats are widely used in biomedical research and are highly social, intelligent animals. Improving their housing and handling significantly reduces suffering without compromising scientific validity.
Laboratory rat welfare has improved significantly since the 3Rs framework gained traction, but gaps remain. Solitary housing — used to prevent fighting or control variables — causes measurable chronic stress in animals that evolved to live in social groups. Environmental barrenness leaves rats without behavioral outlets for their natural curiosity and exploratory drive. Research shows that socially housed, enriched rats produce less variable data, meaning welfare improvements also strengthen science. Pain assessment using grimace scales and ultrasonic vocalizations has advanced enormously, allowing more precise welfare monitoring. Institutional culture and training remain key barriers to better implementation.