Pet Mice Care: How to Keep Your Mice Happy And Healthy

by Alison Blyth
Pet Mice Care

Mice make lovely, relatively low maintenance pets. However, like any other animal, they have needs that must be met to give them high quality of life. Unfortunately, because they are small and cheap, and belong to a group of animals often thought of as pests, the welfare of pet mice is not always fully understood. Here are some essential tips on caring for your pet mice.

Where to get your mice

Like other pet animals, the health and temperament of pet mice depends on their having been carefully bred. If you want to buy your mice, it is worth finding a good quality breeder in your area and visiting to meet the litter, their parents and other adults in the line. Are the animals you meet well kept, healthy and friendly?

However, good breeders can be hard to find in some countries and buying from pet shops is both pot-luck on health and temperament and risks supporting the rodent farm trade. So, its always worth considering adopting new pets from rescues. Many rescue mice looking for homes will be babies born from pet shop mis-sexings, so adoption doesn’t have to mean taking an adult (although rescue adults also need homes and can be very rewarding pets!)

Handling and bonding

Image by Yu-Chan ChenCC BY-SA 2.0

Compared to other small animals like rats, mice are often thought of as quite a hands-off pet. It’s true that, unlike rats, they don’t need to play with their owner every day and have more of a focus on their cage as their home. However, pet mice still benefit from regular handling and strong bonds can be built with their owners. Many people think mice don’t have much personality, but they are just as individual as other small animals. It just takes regular handling to bring out their personalities.

Many pet mice will be happy to climb on their owners, but it is important to be able to pick your pet up so they can be handled to check their health and for any treatment. It is best to pick mice up by scooping them from below, as this provides support and avoids any risk of squeezing them. Never pick mice up by the tail as this can cause damage and pain and may even lead to tail loss. If a mouse is nervous about being handled, it is possible to train them to go into a tube. They can then be removed from the cage that way and scooped up safely once out.

A good way to bond with your mice is to let them use you as a climbing frame and explore your clothes. This gets them used to your sound and scent and associate you with safety. Mice are small and fast-moving and you obviously don’t want them to escape, so it is worth putting some thought into their free-range area. A table is a good option for play space, as long as it is isolated from other furniture, so the mice don’t have anything to climb down (vertical surfaces don’t put mice off scaling down to the floor). If you want to sit and play with your mice, fabric puppy pens or a bath are also good options.

Pet mice lifespan and health

Mice are sadly short-lived pets, usually having life-spans of 1-2 years. Common health problems are respiratory infections and tumours, however, many mice hide medical problems well, and it can be hard to medicate them due to their small size. Any sick pet should be taken to the vet, but mice owners need to be aware medical problems are often acute and may require euthanasia decisions.

Owners of pet mice generally don’t need to bathe or groom their pet. Like rats, mice spend lots of time washing themselves, and owners don’t need to interfere unless the mouse is very old, or has got itself covered in something that it would be unsafe to groom off. In fact, mice are even cleaner than rats and give their tails a good scrubbing.

Do mice need to live together?

Image by Seven MorrisCC BY-NC-ND 2.0

Short answer – yes, in most cases. Mice are a social species, and benefit from having friends to play, groom and sleep with. They are therefore best kept as single-sex pairs or groups. They shouldn’t be kept in mixed-sex groups unless the males are castrated, as they will breed rapidly, which is unhealthy for the females.

Female mice are generally easy to keep together as long as they are introduced to each other carefully (or have grown up together). Females also live happily in pairs or groups with castrated males.

It is often said that male mice have to be kept alone because they become hormonally aggressive. This is a bit of a myth. The levels of hormonal aggression shown will depend very much on the line that the mice come from – so if you are adopting male mice, that’s another good reason to meet the rest of the family and see how they are kept. Often, brothers or nestmates who have grown up together stay together happily in adulthood. Where a mouse does develop hormonal aggression, there is an argument that it is fairer to castrate him than to make him live alone. Castrated males can live with either females, other castrated males, or be carefully introduced to intact males.

Introductions between new mice should be done carefully – don’t just put a new mouse in an existing mouse’s cage. My favourite approach for introducing rodents is to use a small, empty clean cage or carrier that is neutral for all the animals involved. Once they tolerate each other, I add interesting things like ropes or branches, but not furniture like houses with a single entrance that can be defended. However, building 3D nests is very important to mice, so providing lots of nesting material, and a box or house with multiple entrances can really help the bonding process.

Introductions can take anything from hours to weeks. Mouse introductions tend to be quite quick (although castrated male to intact male may take longer), but it is important to be patient, and aware of the way the animals behave.

Housing and cages

The biggest error in buying a cage for pet mice is to choose something too small. There are lots of cages sold in pet shops that are plain unsuitable. I have a small collection of 20 x 30 cm (8 x 12 in) cages which various rescue rats have arrived in – they are epically unsuitable for rats, but I wouldn’t dream of keeping a mouse in them long-term either. In fact, the only things they are good for is being broken up for use as ladders and spare mesh or being used as carriers or intro cages.

The reason these cages are unsuitable is that although mice are small, they are intelligent and very active, so they need room in their home to keep busy and express natural behaviours. The space an animal needs to live in is controlled by what they do, rather than body size. This is particularly important for mice as they spend so much time in their cage and are less likely than larger animals to spend a lot of time playing outside it.

A mouse cage doesn’t need to be particularly tall (40 cm / 16 inches high is a good minimum), but it is important that it has a large enough foot print with a deep base to allow lots of room for cage furniture and thick substrate to dig in (see below). The minimum footprint for a cage for a pair of mice is 65 x 45 cm / 25 x 17 in.

Given the need for a large enough footprint, one challenge in finding a suitable mouse cage is making sure the bar spacing is small enough (0.5 – 1 cm / 0.2 – 0.4 inches depending on the build of the mice), as larger cages are often designed for larger animals like rats. Always check the bar spacing before making a purchase.

Given that they need a deep substrate to dig in, and bar spacing can be a problem, it may be tempting to keep mice in a tank. However, it is important to make sure that they have good ventilation and air circulation (so ammonia doesn’t build up from their urine), and plenty of furniture to allow them to climb. Tanks have only one side (the roof) open to the air, and the need to hang toys and furniture to give the mice plenty to do will block a lot of that ventilation. So, investing in a cage with the right sized bars is much better.

Mouse cage setup, furniture, and enrichment

Image by NuwandaliceCC BY-NC-ND 2.0

Mice need an interesting and well-furnished cage environment. Keeping them in an empty cage will lead to boredom and unhealthy behaviours. Like any other pet, their home needs to let them express the behaviours that are natural to them.

Mice need a nice thick substrate in their cage. They shouldn’t be kept on sheets of newspaper or fleece, as this doesn’t give them enough opportunity to dig and burrow.

Good substrates include:

The use of wood shavings in rodent bedding is controversial, as many brands are dusty, and the woods contain phenols that can cause health problems. However, the use of dust-extracted and kiln dried large shavings is gaining in popularity again, as the pre-treatment should remove both dust and harmful chemicals.

As well as a substrate to dig in, mice need bedding materials to build their nests with. Constructing a nest is a major enrichment activity for mice, so it is important to give them the materials to do it themselves, rather than just a house to sleep in.

Good nesting materials are:

  • toilet roll/ paper towel strips,
  • newspaper strips,
  • and dust extracted hay.

A mixture of materials is better than just one.

Beyond their substrate and nesting materials, a well set-up mouse cage needs:

  • places to hide (huts or tubes or even better, both),
  • things to climb (ropes or branches from fruit trees),
  • and other toys like wheels, boxes and baskets.

Remember, a mouse can’t use empty space in the middle of a cage, so setting up levels, either with shelves or ropes and branches strung across the cage helps them use all the space better. Ropes and branches also provide a healthier and more challenging way to get about the cage than ladders do.

The advantage of the small size of mice is that many interesting cage toys can be found round the house – saving cardboard boxes from foot packaging and the inners of toilet rolls gives a regular supply of hidey-holes.

Feeding – what do pet mice eat?

Feeding pet mice

It is possible to buy commercial “complete” diets for mice, but the breeder I consulted in writing this article feels they are often poor quality. It’s also important to be aware that many commercial foods come as pellets. These may be nutritionally complete, but they are also incredibly boring. Mice, like all captive animals, derive a lot of interest and pleasure from interacting with their food, and being fed an identical pellet every day for their whole lives takes that away from them. If you want to feed rodent pellets it is best to make them only one part of the diet.

Feeding mice is very similar in principle to feeding rats, with some adjustments for their differing needs. The bulk of their food should be a museli-style grain based dry mix, with fresh vegetables, fruit, and protein for added interest and micronutrients.

The major difference between rats and mice is that mice need more protein. A good way to provide this is to adapt a dry mix designed for rats (commercial or home-made) by adding a dog or cat kibble, chicken pellets or pig pellets. Pellets shouldn’t make up more than 40% of the mix, and if using a high protein kibble, adding more grains, lentils, and peas will help reduce the overall fat content.

Mice in the wild spend a lot of time foraging for food, so it is very healthy for pet mice to have food-based enrichment in their cages. This might include toys like:

  • food filled paper pinatas or vegetable kabobs,
  • or scatter-feeding of dry mix in the substrate so they have to dig to find it.

Pet mice should always have access to fresh clean water. The best way to provide this is in a gravity fed bottle, so it doesn’t get contaminated with bedding.

Conclusion

Mice make delightful pets, and by making sure they are well kept, with plenty of interesting things to do, healthy food, and lots of handling, owning them should be a rewarding experience for pet and owner.

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