There are many species of mice in the world but the most common pet species is a domesticated version of the 'house mouse' or Mus Musculus. Mice are omnivorous - meaning they naturally eat a mixture of meat and plant matter. Although they are naturally nocturnal, pet mice are not generally as strictly nocturnal as hamsters for example and will adapt their behaviour in accordance with their owner's lifestyle. Mice have been kept as pets since at least the 17th century and, in that time, have been selectively bred to produce a wide variety of coat colours. Mice generally live around two years.

Housing your mice

There are three basic types of mouse habitat. A cage, a tank or a modular cage such as a rotastak.

Rotastak style cages are not generally recommended as suitable housing for mice. They have poor ventilation and do not provide the mice with enough open space to run around in. The different pods and compartments can also encourage territorial behaviour.

Some people opt for tanks as they solve the issue of mice being able to escape from many barred cages. However, tanks also have limited ventilation which can be an issue for mice with their sensitive respiratory systems. The lack of bars also means the mice cannot climb (which they love to do) and it's difficult to make good use of all the space for them. This can lead to them becoming bored.

Traditional cages provide good ventilation and opportunities for the mice to climb and interact with you. However, mice can escape through many bar spacings so care must be taken to use a cage with bar spacing of no more than 9mm for adult mice.

A good-sized cage is essential. As a minimum you should provide a square foot per mouse. If the cage has a wire base, be sure to at least partially cover it or provide solid shelves so that the mice don't have to spend too much time on the bare wire as this can cause foot problems. You’ll want to get a balance between height and floorspace as mice appreciate both. A very tall, thin cage or very low, wide cage will not be ideal. Younger, more active mice will want more height, whereas older, slower mice will probably appreciate more floor area.

Your mice will appreciate cage furnishings such as hammocks, tubes, ladders, ropes, wheels (solid, not barred) and igloos. The cage should be placed away from direct sunlight or drafts. Never put the cage in a conservatory or sun lounge as mice can overheat quickly.

Substrate and bedding

It is very important to use the right type of substrate as the wrong material can have serious health implications. As a basic guide, paper and cardboard-based products are good (eg shredded paper, megazorb, finacard). Some paper based cat litters are ok but can be dusty or scented which isn’t ideal. Never use clay based litters, scented products or any product containing soft wood (eg wood based cat litters, sawdust and wood shavings). There is considerable evidence to suggest that these can cause liver and lung damage in small animals.

How often this bedding needs changing depends largely on the number of mice you have and how much space they have. As a general rule though, you will probably want to do a full clean once a week (including washing down the tray, shelves and bars of the cage) and a smaller clean in between in which you clean out toilet areas.

Mouse diet

There are various pre packaged mouse foods available but the quality is extremely variable. Avoid mixes which state they are for mice and hamsters for example - the two species have different dietary needs and hamster mixes may be too high in fat. Avoid foods which are too high in peanuts, sunflower seeds or corn which should only be given in moderation.

Some owners prefer to create their own mixes in order to control the quality of the ingredients. The dietary needs of mice are very similar to those of rats so a home made mix can be based on the shunamite diet, created by rat breeder and nutritionist Alison Campbell. You can find information about this approach at www.shunamiterats.co.uk/shunamite.shtml

In addition to dried food, your mice will enjoy fresh foods. These should be introduced slowly and in moderation as too much can cause diarrhoea. Good things to give them include cucumber, peas, banana, apple, broccoli, carrot and mealworms. Although leafy greens like spinach and lettuce are not harmful in themselves, they are more likely to cause diarrhoea so should be given only in very small amounts. Avoid giving them too much salt or sugar or foods too high in fat.

Never give your mice carbonated drinks, alcohol, fruit and vegetable peelings (may contain pesticides) or citrus rinds.

Water should be provided in a bottle (not a bowl which will soon get messy) and should be changed daily.

Companionship

Mice are highly sociable animals so it is absolutely essential for their wellbeing that they have company of their own species. Female mice are very easy to keep together and unrelated adults can be introduced quite easily by allowing them to meet first on neutral territory. Male mice are more complicated and it is not generally possible to introduce them as adults. Established pairs and groups can fall out and fighting can become serious. Careful management of their environment can often help to keep them together however. Placing a squabling group into a small, bare cage (so they have nothing to fight over) for a few days can reduce tensions. You can then increase space and enrichments gradually but watching carefully for any serious fighting so you can separate them before injuries occur. It is possible to have male mice neutered which can allow them to live happily together or to live with females. The operation would need to be done by an experienced exotics vet but it is definitely worth considering if the alternative is a lonely mouse.

Sexing your mice

Sexing mice is quite straightforward. Like all pet rodents, the females have visible genitals/urinary openings which can be confused with a penis. The important thing to look for is the size of the gap between this and the anus. In females, the two openings are very close together with no furred skin between the two. In males you will see a noticeable gap including some fur. In mature males, there are also visible testicles.

If you are not confident in sexing mice, be sure to acquire your pets from someone who is. Pet shops often mis-sex rodents and they can breed quickly and prolifically. There are many mice looking for homes in rescue centres and males can be hard to find homes for so please do all you can not to add to the over population problem. If you find you have mice of both genders, please seek help from a specialist rodent rescue urgently. Bear in mind that pet shops, vets and rescues which do not specialise in rodents may not be able to determine the gender of rodents reliably.

Interacting with your mice

You may find that your mice are initially shy of being handled. This is natural and normal and all you need is gentle persistence and understanding to help them to get used to you. Begin by making friends with your mice while their feet are on the ground by offering them treats and talking softly to them. You can initially encourage them to walk into a tube and then from the tube on to your hand or lap if they are nervous about being picked up. Once they are out you can get them used to being handled by scooping them with both hands rather than “grabbing” them. Always handle your mouse sitting down, ideally on a bed or sofa so the mouse has a soft landing if he jumps! Never pick your mouse up by his tail.

It’s important that mice get exercise and mental stimulation or they can display frustrated behaviour such as bar chewing or squabbling. Ideally your mice should be handled and given the chance to explore outside of their cage every day. This should be in a safe, secure area where things which may harm them such as heavy objects they might knock over, other pets, electrical wires, potential toxins and sharp objects are removed. Mice can find large open spaces intimidating so, at least initially, you might find it best to free range him in a smaller area. Sitting on the bed or sofa with them is ideal. Bear in mind that mice can get into tiny gaps and will seek to do so if scared. So be sure to check for gaps under furniture for example before letting them loose.

We do not recommend using hamster balls for mice. They tend to find them scary and their long, thin tails can get caught in the ventilation gaps.

You and your mice can also have hours of fun constructing a play area and obstacle course with things for them to climb on etc.

Mouse health

Your mice should be handled daily and as part of this you should perform a health check. Check eyes and nose for any discharge (a reddy coloured discharge known as Porphyrin can be a sign of ill health), check for lumps, check the skin for any wounds, scabs or flakiness (could be mites) and listen to their breathing (noisy breathing could suggest a respiratory problem). Loss of co-ordination, weight loss and increased thirst are also possible signs of illness. Mice have very fast metabolic rates so can succumb to illness quickly. It is therefore essential that you see your vet promptly with any concerns.


This information is intended as a basic guide to caring for this type of animal. If you intend to get some mice please ensure you research their needs thoroughly and that you can offer them everything they need for the duration of their lifespan. If you have any questions which are not covered here you are very welcome to Email us.