Mice come in a wide variety of colours and live on average for between one and a half and two and a half years. They are fully grown at about three months old. Babies should not be taken from their mothers until they are five weeks old. Never attempt to keep wild mice as pets.
Mice need the company of their own kind and, to avoid unwanted babies, it is best to keep pairs or groups of females.
Female mice reach sexual maturity at five weeks old. A breeding pair will produce a litter every three to four weeks, with an average of eight to ten babies and females can become pregnant within 24 hours of giving birth. It is strongly recommended not to breed mice as you will quickly become overrun!
Males tend to be more aggressive towards each other than females and have a stronger smell because their urine contains a musk-like substance. For this reason, females tend to be a better choice of pet.
Home comforts: Mouse cages and bedding
The best home for your pet mice is either a wire cage with a plastic tray floor or a tank (glass or plastic) with a secure wire lid. Wooden cages absorb urine and tend to become smelly. Two mice need a cage size of at least 60cm x 50cm floor space, by 30cm tall. This gives them more than enough room to stand upright. Mice like to climb, which wire cages allow, but they can squeeze through tiny gaps so spaces between the bars should not be larger than the width of your little finger.
Put bedding on the floor to absorb urine. Dust-extracted bedding or shredded paper are best as dusty or scented bedding may affect a mouse’s delicate respiratory system.
Don’t use cedar shavings as these can cause health problems. The cage should also contain a nest box filled with shredded tissue paper.
Clean out the cage at least once a week – more often for males. Take out soiled and wet bedding but, to make sure your mice are reassured by a familiar smell, mix in a little of the old bedding (and if necessary, nesting material) with the new.
Make sure your mice’s home is away from draughts and direct sources of heat and is somewhere they can’t be harassed or attacked by other pets.
Diet: What to feed a mouse?
A small amount of commercial rodent mix is a good basis for a mouse’s diet – but be careful not to let your pets get fat.
Mice love sunflower seeds as occasional treats and may also enjoy tiny amounts of suitable vegetables and fruit, like carrots, apples and broccoli. Contrary to popular myth, mice do not need cheese or dairy food and some also react badly to peanuts. Clean, fresh water should always be available from a drinking bottle.
Common health problems to mice
Mice are pretty robust but, because of their short lifespan, are susceptible to problems associated with ageing. They are prone to mammary tumours and other tumours in places like behind the legs and on the neck. They may also suffer from respiratory problems due to bacterial or viral infections. If you are worried, seek veterinary advice quickly – tiny pets deserve as much consideration as larger ones.
Exercise and enrichment for mice
Mice love anything that allows them to climb, so make sure they are able to do this. If you use a tank, they will appreciate a fruit tree branch to climb on. Alternatively, you could suspend lengths of rope as climbing apparatus.
Your mice will also enjoy going through tunnels, such as cardboard or plastic tubes. Remember that by giving them these opportunities you are encouraging them to follow their instinctive behaviour. Some owners like to half fill a cardboard box with compost and allow their mice supervised tunnelling sessions
Do mice like company?
Mice need their own kind as company and love to groom and play with each other. Do not mix mice with pet rats or other rodents, as they may be attacked and eaten. It is usually safe to mix female mice up to the age of about 12 weeks even if they are from different litters.
How to handle a mouse
Although mice are usually friendly and rarely bite, some may be naturally more timid than others. Start by placing your hand quietly in the cage, holding a treat such as a few sunflower seeds. When the mice get used to taking this from you, teach them to anticipate food by making the same sound each time, like a whistle.
To pick up a mouse, hold the base – not the tip – of its tail gently but firmly, then lift the back end gently and slide your hand under the mouse’s body. Children shouldn’t handle mice or any other pets unless they are supervised.
Mice as children’s pets
Mice are very small and quick, so may be difficult for small children who want a pet they can handle. Male mice have quite a strong smell so need regular cleaning. As with all pets, it is important that parents take responsibility for ensuring that their children’s pets are properly cared for.