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Choosing Mice: Part One

How Old Should Mice Be When I Get Them?

Baby mice are fully weaned at around four weeks old but they benefit a lot from staying with their litter mates for another week - the disruption of leaving both mother, siblings and home in one day is a lot to cope with. Ideally they should not leave the litter before five weeks of age. If you get them when they are too young they will be jumpy and hard to socialise at first.

Some pet shops will offer mice for sale as soon as they start to eat solid food, at about two to three weeks of age. However, although mice this young eat solids, they really do need their mother's milk for another couple of weeks. Mice weaned this early often don't survive. Mice are not fully grown until at least 12 weeks of age, although many mice take longer than this to reach full size.

These mice may look old enough to become pets but they are only three and a half weeks old, and still need their mum

What Sort of Things Should I Look For?

You need to check a few things when purchasing a mouse. When choosing your pet, look for active mice with smooth clean coats, clean pink skin on the ears and tail and bright eyes. The eyes and nose should be free of discharge and the mouth and anal areas should be clean and dry. Their breathing will be relatively fast, but should not be laboured or noisy. Check the cage as well - it should be clean (showing that the mice have been well cared for) and the droppings should be formed.


Be sure to check thoroughly that you are getting mice of the same sex unless you are intending to breed. Mice can produce a large litter in just three weeks, so be careful if you're not planning on being overrun with babies! If you can learn to sex the mice yourself before buying this is better than relying on a shop assistant to check for you.

Where Should I Get My Mouse From?

You should make sure that you get your mouse from a good source (i.e. a reputable pet shop with good clean premises, cages and knowledgeable staff, or a breeder with experience). Never try to capture a wild mouse. These mice may be attractive but you are extremely unlikely to tame them. It is cruel to take a mouse out of its habitat like this, especially when there are plenty of places to get a tame and happy pet mouse.

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