Mice as Pets: The Beginner’s Guide

🐭 The short version: mice are the tiny, quick, endlessly busy pet for people who love watching an animal build, burrow and forage. They’re social and cheap to keep well — but the social side is exact: female mice thrive in groups, adult males usually fight, and a lone mouse is a lonely one. Give them a big tank with deep bedding to dig and the right cage-mates, and they’re a delight.

🔧 Tools for your mouse: is my cage big enough? · what can it eat? · is this normal?

The social rules — get these exactly right

Mice are social and shouldn’t be kept alone. But the grouping is specific:

• Females generally do very well in compatible single-sex groups.
• Adult males are often aggressive toward one another and frequently can’t be housed together. The safest male groups are same-litter brothers grouped before weaning and never disturbed — otherwise a male may need to live alone.
• Never introduce unfamiliar adult males, and keep established groups stable.

One more catch: shop-sexed mice are often mis-sexed. Check the sexes yourself, or you’ll end up with a surprise litter.

Housing

A large, secure, escape-proof enclosure — a big tank or a cage with very narrow bar spacing (mice squeeze through tiny gaps) — with plenty of floor space and, crucially, deep bedding to dig and tunnel in. Add hides, nest sites and things to climb, plus a solid exercise wheel. Keep it in a settled spot out of direct sun.

Use a deep layer (at least ~2 cm, ideally more) of non-aspen wood chips, cellulose chips or shredded filter paper, plus plenty of nesting material — mice are keen nest-builders. Avoid fine sawdust, wood shavings, aspen, cedar, and fragrant or dyed bedding.

Temperature

Mice are very sensitive to heat. Keep the cage out of direct sun and away from temperature extremes and high humidity (not a conservatory, garage or air-conditioned room), and move it somewhere cooler in a summer heatwave.

Diet

Mice are opportunistic omnivores. Feed a good-quality, balanced mouse food (a proper mix or pellet) as the base, plus small amounts of fresh fruit and vegetables as part of — not on top of — the daily ration, scattered to encourage foraging. Provide constant fresh water. Don’t feed grapes, raisins or rhubarb (poisonous to mice) or lettuce (it causes diarrhoea).

Health

Because they’re prey animals that hide illness and their lives are short, watching appetite, weight and breathing is the best early-warning system you have. See a vet for sniffling, sneezing, a chattering noise or laboured breathing (respiratory infection, often Mycoplasma, is common), diarrhoea or weight loss, any lump (mammary tumours are common), or scratching and hair loss (mites). At their size, problems escalate quickly, so have an exotic vet that sees mice.

The honest takeaway

Housed in the right group with a big, deep-bedded tank, mice are cheap, fascinating and easy to care for — hours of entertainment watching them build and forage. Most mouse problems come down to grouping and enclosure size, both simple to get right from the start. See the full mouse care guide for the complete spec.

Sources & further reading

• Hayfold — mouse care guide — the full, fact-checked reference.
• RSPCA — mouse environment, diet and company.
• Merck Veterinary Manual — mice — respiratory disease, tumours and lifespan.