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Guide6 min read

Rat Welfare Research

Published

The welfare evidence on pet rats points the same way on five things. Rats need company from other rats, a cage tall enough to stand up and climb in, more than one place to hide, things to forage and dig through, and clean, well-ventilated air. Below is what UK welfare charities and published research say on each, with the sources, and the guide of ours that turns it into a cage setup.

At a glance

  • The RSPCA, Blue Cross, NFRS and PDSA all advise keeping rats in groups of at least two.
  • Blue Cross recommends at least 90 × 60 × 120 cm of living space for two to five rats.
  • A fully grown rat stands 26 to 30 cm tall on its hind legs.
  • Give one hide per rat, plus one spare.
  • The RSPCA describes 19 to 23°C as the ideal temperature range.

Company: why rats should not live alone

The RSPCA, Blue Cross, the National Fancy Rat Society (NFRS) and PDSA all advise keeping rats in groups of at least two. The RSPCA notes that rats kept alone are more likely to develop behaviour and health problems.

In a 2020 laboratory study (Begni and colleagues, PLOS ONE), rats housed alone became hyperactive and had lower levels of brain-plasticity markers in the prefrontal cortex. Some of these changes eased once the rats were housed with others again.

In the UK, section 9 of the Animal Welfare Act 2006 puts a duty of care on owners. One of the needs it names is an animal's need to be housed with, or apart from, other animals.

In practice: keep a same-sex pair or small group, and introduce newcomers slowly. Our carrier method guide covers introductions, and our lone rat guide covers what to do when a cage mate dies.

Space: why cage height matters as much as floor area

Blue Cross recommends at least 90 × 60 × 120 cm of living space for two to five rats. Larger groups need more.

Height matters because rats stand up. Makowska and Weary (Royal Society Open Science, 2016) found that a fully grown rat stands 26 to 30 cm tall on its hind legs. Rats in standard 18 cm laboratory cages could not stretch fully upright and stretched sideways instead, a recognised sign of compromised welfare.

The RSPCA describes 19 to 23°C as the ideal temperature range. Keep the cage indoors, away from direct sun, draughts, smoke and strong smells, with gaps too small for the smallest rat to put its head through.

In practice: our rat cage setup guide covers size, cage type and placement.

Shelter: hides, nesting and a way out

Rats use covered spaces to rest, retreat and watch. The common guidance is one hide per rat, plus one extra, so no rat can guard the only retreat. A hide with more than one way through lets a rat choose how to come and go.

Nesting material matters too. Use paper-based bedding. Avoid cedar and pine shavings: the aromatic oils in these softwoods are harmful to rats.

In practice: our rat hide guide covers fit and entrances, and our cardboard and longer-term hides guide covers when to replace a box.

Climbing and digging

Rats explore in three dimensions. Makowska and Weary's 2016 study looked at burrowing, climbing and standing upright. Burrowing is what researchers call an inelastic behaviour: rats keep doing it throughout their lives, whatever their age.

In practice: give shelves and ledges at different heights, with at least 30 cm of clear space between levels so a rat can stand up. A dig box 15 to 20 cm deep, filled with shredded paper or coco coir, lets them dig without making the whole cage hard to clean. Our rat cage accessories guide covers what to add and where.

Foraging and enrichment

A 2022 metareview in Animals found that rats housed without environmental complexity develop repetitive behaviours such as bar-gnawing and pacing, higher levels of the stress hormone corticosterone, and more anxiety in standard behaviour tests.

A 2025 study in Frontiers in Veterinary Science found that rats in enriched housing showed less anxiety, more exploration and better learning and memory than rats in barren housing. A 2025 study in Scientific Reports found that regularly changing the enrichment encouraged exploration and supported positive welfare.

In practice: use part of their normal daily food for searching and foraging, and change one thing at a time. Our 35 enrichment ideas and enrichment guide show how.

Our Fairy Mushroom rat cage kit puts a hide, shelves and foraging cups in one matching set.

Clean air and breathing

Nearly all pet rats carry Mycoplasma pulmonis, a bacterium that affects the airways. It cannot be eliminated and stays for life, but in many rats it stays quiet. Flare-ups are triggered by ammonia from dirty bedding, dust, scented products, temperature swings and stress.

That is why ventilation and cleaning are welfare questions, not just housekeeping. Wire cages let air move freely; glass tanks let ammonia settle at floor level.

In practice: our cage cleaning guide sets out a routine, and our respiratory guide covers what to record.

Reading the research with care

Most of the studies above used laboratory rats. Pet rats are the same species, but home cages, groups and routines differ, so read the studies as a direction rather than exact rules. Where UK charities give a figure, such as cage size or temperature, we use theirs.

Sources

UK welfare guidance and law

Research

This page summarises published guidance and research for pet owners. It is not a substitute for advice from your vet.

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Compare hides and cabins, foraging toys or the whole rat care range.

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