Care guide · Mice

How long do pet mice live? Lifespan and life stages

Checked against MSD Veterinary Manual: Description and physical characteristics of mice, MSD Veterinary Manual: Breeding and reproduction of mice, MSD Veterinary Manual: Special considerations for mice and 11 more on

Pet mice usually live 1.5 to 2.5 years, and a well-kept mouse sometimes reaches 3. That is roughly twice the average life of a wild house mouse, which is about a year. Lifespan depends most on the breeder line, a healthy weight, the right food, company of other mice and a cool, clean, dust-free cage.

How long do pet mice live?

Most pet mice live between 1.5 and 2.5 years. That is the range given by the MSD Veterinary Manual, and PetMD puts it at 18 to 24 months with some living longer. PDSA, RSPCA Australia and the Oxfordshire rescue Crittery give a wider spread of 1 to 3 years, and Woodgreen says 1 to 2.

The sources agree more than the numbers suggest. A mouse that dies at 12 months has usually had an illness or an inherited weakness, and a mouse that reaches 3 is the lucky top end. We'd plan on about two years and treat anything after that as a bonus. That also tells you something practical: with mice, you will face loss more often than with most pets, so it helps to keep a group of mixed ages, as Crittery suggests, so nobody is left alone.

How long do white mice live?

White mice live as long as any other pet mouse: 1.5 to 2.5 years. A white mouse is not a different kind of animal. It is a fancy mouse in one of the standard "self" colours, a single colour all over, which the National Mouse Club lists alongside black, blue, champagne, cream, dove, fawn, lilac, red and silver. The MSD Veterinary Manual lists albino as one of the common pet colours.

What changes lifespan is the line a mouse comes from and how it is kept, not its coat. For more on colours and coat types, see our guide to pet mouse breeds and colours.

Pet mouse life stages

A mouse packs a whole life into two years, so each stage passes fast. These ages come from the National Mouse Club, the MSD Veterinary Manual and the American Fancy Rat and Mouse Association.

Stage Age What is happening
Newborn 0 to 2 weeks Born hairless, deaf and blind. Ears open over the first four days, eyes at about 12 days. By two weeks they look like tiny adults.
Weaning 3 to 4 weeks Weaned at 21 to 28 days. Young males must leave their mother and sisters by about 4 to 4.5 weeks.
Young mouse 5 to 8 weeks Ready for a new home from about 5 weeks. Mature and able to breed at 6 to 8 weeks.
Adult 2 months to about 18 months Full size: 6 to 8 cm (2.5 to 3.5 in) of body, 20 to 40 g (0.7 to 1.4 oz). Busy, curious, at their most active.
Older mouse From about 18 months Slower, sleeps more, may lose weight or grow lumps. Needs closer checks and easier access to food, water and nest.

No source sets an exact "senior" age for mice. We've put it at around 18 months because that is where the typical lifespan range starts, and it is when PDSA and Woodgreen's list of older-mouse problems, such as tumours, arthritis, heart disease and failing sight, tends to show.

What shortens a pet mouse's life?

Most of what cuts a mouse's life short is avoidable. These are the big ones, with what the welfare charities and vets say about each.

  • Dusty or scented bedding. PDSA warns that wood shavings and sawdust can cause breathing problems, and Woodgreen lists breathing illness as common in mice. Paper or card bedding is safer. Our guide to pet mouse bedding goes through the options.
  • Being too fat or too thin. Crittery says obese or underweight mice are more prone to illness. Feed about 3 to 5 g (around a teaspoon) of mouse nuggets each a day, and keep treats under 10% of the diet, as PetMD advises. See our pet mouse diet guide.
  • Heat. The MSD Veterinary Manual gives a safe range of 18 to 26°C (64 to 79°F) and warns of heat stroke above 30°C (86°F). PDSA's ideal is 18 to 22°C (64 to 72°F). Our mouse temperature guide covers where to put the cage.
  • Living alone or in an unstable group. The RSPCA says mice should not live alone unless a vet advises it, and that adding or removing even one mouse can cause stressful conflict for the whole group.
  • Fighting. Adult males often fight if they did not grow up together. Separate any mice if blood is drawn, as PDSA advises.
  • Breeding. A female can fall pregnant again within 24 hours of giving birth, according to the MSD Veterinary Manual. Back-to-back litters wear a doe down, which is why same-sex groups matter.
  • Problems spotted too late. Mice hide illness well. A weekly hands-on check is the single habit most likely to catch something in time.
Weigh each mouse once a week on kitchen scales that read in single grams, in a small tub. A steady drop of a few grams over two or three weeks is often the first sign of trouble, long before a mouse looks ill.

How to help your mice live longer

  1. Start with healthy mice. A good rescue or breeder who keeps healthy lines gives you the best start. Look for a glossy coat, clear eyes, no discharge and no sneezing. Our guide on where to get a pet mouse lists what to check.
  2. Keep them in a settled same-sex group. Females in a group of three or more usually live happily together. Males are best kept as brothers raised together, or as a neutered male with females.
  3. Give them a big, airy home. Woodgreen recommends at least 80 × 50 × 35 cm (31 × 20 × 14 in) for three or four mice. Our cage size guide has the full table.
  4. Use paper bedding and clean regularly. Spot clean daily and do a full clean every one to two weeks, keeping a handful of clean old nesting to put back.
  5. Feed a complete mouse food. A pellet or nugget means every piece has the same nutrients, as PDSA points out. Add small fresh extras, and keep sugary cereals under 5% sugar, as Woodgreen advises.
  6. Check each mouse weekly. Look at teeth, eyes, nose, coat, bottom and belly, and feel gently for lumps. Our pet mouse health guide lists the warning signs.
  7. Find a mouse-savvy vet before you need one. Not every practice sees mice often. An exotics vet is worth finding while your mice are well.

Signs your mouse is getting old

An older mouse slows down gradually. These changes are normal with age, but any sudden change still needs a vet.

  • Sleeping more and coming out later in the evening
  • Less climbing and less time on the wheel
  • A thinner, rougher or patchy coat, and less grooming
  • Losing weight, often felt as a bony spine and hips
  • Teeth that look deeper orange-yellow, which PetMD says is normal with age
  • Stiff, slower movement, which may be arthritis
  • Cloudy eyes or bumping into things
  • New lumps, especially along the belly and sides

Caring for an older mouse

Small changes make a big difference to an older mouse. Lower the climbs and add ramps, so the nest, food and water can be reached without a jump. Scatter some food near the nest as well as across the cage. Soak a few nuggets in water to soften them if a mouse is struggling to eat, and offer small amounts of soft foods from our safe food list. Keep the cage warm enough, at the upper end of 18 to 22°C (64 to 72°F), and out of draughts.

Keep the group together if you can. An older mouse kept warm by cagemates usually does better than one moved to a cage of its own. Only separate it if it is being bullied or a vet advises it.

Lumps grow fast in mice. PDSA says mammary tumours are very common, that surgery carries risk and that they often come back. See a vet as soon as you find a new lump, as small lumps give the most options.

When to see a vet

See a vet the same day if a mouse stops eating, breathes fast or with effort, sits hunched with squinted eyes, has diarrhoea or a wet bottom, has a head tilt, or is bleeding. RSPCA Australia lists sneezing several times within an hour or two, wheezing, and sudden squealing as signs of illness too. Book an appointment within a few days for slow weight loss, a new lump or overgrown teeth.

When an older mouse is in pain that cannot be eased, a vet can help you decide when it is kinder to let it go. It is a hard choice, and a gentle one. Afterwards, watch the remaining mice closely and think about how to keep the group at three or more.

How long do pet mice live compared with other small pets?

Mice have one of the shortest lives of any pet. Among the small pets we cover, rats usually live a little longer, at around two to three years, as our rat lifespan guide explains. If a short life worries you, read our page on mice as pets first, then the full pet mouse care guide.

Pet mouse lifespan questions

How long do white mice live?

The same as any other pet mouse: usually 1.5 to 2.5 years, sometimes 3. White is one of the standard colours of fancy mouse, listed by the National Mouse Club alongside black, blue, cream and others. Colour on its own does not set lifespan. Care, genes from the breeder line and luck matter far more.

Do male or female mice live longer?

No good source shows a clear difference. Each sex has its own risks. PDSA says mammary tumours are very common in mice, and they mostly affect females. Males are more likely to fight once grown, and the MSD Veterinary Manual warns that fights cause injuries. Keeping either sex well means planning for those risks.

How long do wild mice live?

Much less time than pets. The Wildlife Trusts give the house mouse and the wood mouse an average lifespan of about a year, and the tiny harvest mouse about 18 months. Predators, cold and hunger end most wild lives early. A pet mouse with good care often lives twice as long.

What kind of cage should mice be kept in?

A large barred cage with a solid floor, or a well-ventilated tank-style home with a mesh lid. PDSA says bars should be no more than 6 mm apart, and Woodgreen recommends at least 80 by 50 by 35 cm (31 by 20 by 14 in) for three or four mice. Add deep paper bedding and several hides.

Can a mouse live alone?

It can survive, but it should not have to. The RSPCA says not to keep a mouse alone unless a vet recommends it. Mice are social and need others of their own kind. A lone mouse also loses the warmth and grooming of a group, which matters more as it ages.

What noises does a mouse make?

Mostly ones you cannot hear. RSPCA Australia says mice talk to each other above the range of human hearing. The sounds you do hear are soft chirps, squeaks, the odd hiss and a gentle teeth-grinding. Sudden squealing, sneezing or wheezing is worth noticing, as it can mean pain or a chest problem.

Sources

Keep track of your own mouse

Add their birthday once and we work out their age and life stage, with a weight log beside it. Everything stays on this device.

Read next

Pet mouse care: the complete guide

Keep mice in same-sex groups in a big barred cage with deep paper bedding, hides, a solid wheel, about 5 g of mouse nuggets each a day and daily spot cleans.

Pet mouse health: signs of illness to watch for

Hunched posture, ruffled fur, clicking breaths, weight loss, lumps or not eating mean a mouse needs a vet the same day, as mice hide illness until late.

Pet mouse diet: what to feed every day

Feed each mouse 3 to 5 g (a level teaspoon) of complete nuggets a day, with small bits of veg inside that allowance, a little protein and fresh water always.

Pet mouse temperature guide: too hot, too cold and just right

A mouse's body runs at 36 to 38°C (98 to 101°F). Keep its room at 18 to 22°C (64 to 72°F), never above 26°C (79°F); over 30°C (86°F) risks heatstroke.

Male or female mice: groups, pairs and living alone

For most people, a group of three or more female mice is easiest. Males often fight once grown and smell stronger; a neutered male can live with females.

Pet mouse facts: surprising things about pet mice

Mice talk mostly in ultrasound, have hearts beating 450 to 600 times a minute, cool off through their tails and can have up to 15 litters a year.