Nesting Material for Laboratory Mice

Providing nesting material is one of the simplest and most impactful welfare improvements for laboratory mice.

Key Facts

Nesting is a fundamental behaviour for mice used to construct shelters for thermoregulation
Mice without nesting material show elevated stress hormones and reduced immunity
Providing 3g of nesting material reduces physiological stress markers significantly
Nests improve welfare without compromising experimental validity in most study designs
The 3R framework requires enrichment including nesting as standard practice

Welfare Considerations

Laboratory mice without nesting material experience chronic thermal stress and frustration of a fundamental behavioural drive. Providing a simple 3g nest square reduces corticosterone levels, improves body condition, and allows normal thermoregulatory behaviour. This is one of the best-documented and easiest-to-implement welfare improvements in animal research. Resistance to nesting provision based on concerns about experimental validity is generally unfounded according to the research literature.

What You Can Do

Support research institutions with strong 3R implementation policies
Advocate for mandatory enrichment standards including nesting in animal research guidelines
Learn about the 3Rs framework — Replace, Reduce, Refine — in animal research
Support alternatives to animal testing where scientifically valid
Ask institutions about their enrichment and welfare monitoring policies