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The pet shop sold me a male and a female – what do I do now?

The first thing you should do as soon as you discover this is to separate the pair (or take the male out if there is more than one female in with him). Depending on how old they are you are likely to have a pregnant female, so you must be prepared for babies. You will always have to keep the male and female separate unless you want more babies (not a good idea if you don’t know the history of the parents) and therefore you’ll need at least two cages. If you have noticed within a few days of buying the animals, the pet shop may take one or both back.

Does can get pregnant from as young as five weeks old, so if they are old enough to be away from their mother they are old enough to have their own litter! Getting pregnant at a young age can be harmful to both mother and babies, so she will need to be well looked after during the three weeks she is pregnant, the five weeks she is looking after the babies and of course afterwards when she is recovering. The food mix a pregnant doe receives, the location and temperature of the cage and the amount of noise nearby can all influence the mother-to-be, so make sure you work out the best possible scenario for your mouse.

Mice are pregnant for 19 to 21 days (more usually 21 in my experience) and will then give birth to a litter of anything from a single baby upwards. The average is probably around 10 but they can have as many as 20 so beware! During pregnancy you need to feed a fattier mix to build up reserves for milk production etc. Adding bird seed, dry dog food and even meat (such as turkey or chicken) can help. Mice can also be given wholemeal bread (not too fresh) with cod liver oil on. This can also help mice who are having a little trouble with labour, although if you are worried you should take your mouse straight to the vet.

You are not likely to know exactly when your mouse conceived and therefore you can’t know exactly when she is due to have her babies. She will start to get fat at around two weeks of pregnancy and will continue to grow until she looks as though she has swallowed a golf ball. It is at this time you know she is due very soon and can prepare the cage. A couple of days before you believe your mouse to be due it is a good idea to give the cage a thorough clean. Provide plenty of bedding and make sure there is nothing that could hurt the babies when they arrive (this might include removing tubes that babies could get abandoned in or fall down, taking out the wheel and providing safe bedding – i.e. not the cotton wool-like bedding sold in pet shops). Always give plenty of food and water as a perceived shortage by the mouse (she doesn’t know you will be back every day to fill it up when it runs low) might mean she destroys some or all of the babies when they arrive.

Since you and the mouse are new to each other you probably haven’t had a chance to bond and she may not trust you fully. For this reason try not to disturb her when you discover that she has given birth (she will suddenly be thin again and there will probably be tiny squeaks coming from the cage). Give her time to settle down with the babies and don’t try to get her out for a few days (unless, for example, she climbs out onto your hand when you are filling her food bowl/water, and even then only for a few seconds to check she’s ok). For a young first-time mother and/or a nervous mouse you should wait around four days before handling the babies for the first time. You can extend this if you feel that your mouse is not ready – you are the best judge of this because every animal is different. When you do decide to handle the babies for the first time you must follow the correct procedure to help guard against rejection by the mother when you replace the litter.

First of all you must wait for the mother to voluntarily leave her nest so that you can pick her up. When you put her down to handle her babies it is best to put her in a carry tank where she cannot see you interfering with her litter. Then, rub your hands in the dirty substrate/bedding in the cage so that you smell more ‘mousey’ and disguise your human smell a bit. Carefully open a small hole in the nest (leave it as intact as possible in order to replace later) and begin handling the babies. Only hold each for a few seconds and make sure your hands are warm as pinkies get cold very quickly. Make sure you replace all the babies in the nest and cover them over gently as they were before you disturbed them before putting mum back. Each day that you handle the babies you can slightly increase the time that you hold them for in order to get them more used to you.

When the babies reach two weeks old they will start to open their eyes, at which point you will find them wandering about outside the nest and they will start to sample solid food. They may also become jumpy (known as ‘the flea stage’), which is a natural reaction to possible danger as well as their new perceptions of things around them. Careful handling of the babies throughout this period is important and will help them to become calm more quickly. Some babies never go through this stage so you may not even have to deal with it at all, but it is more likely that you will so be prepared.

Between the ages of four and four and a half weeks you need to separate the baby boys from their mum and sisters. To do this have a look at the sexing pages of this website. The bucks should be housed together in another tank or found homes for. It is possible that the group may start to squabble after a while but I usually find that brothers remain happy to live together, especially given the right size of cage. The baby does can stay with their mother for as long as desired but should remain with her until they are at least five weeks old if you plan to rehome them or separate them for whatever reason.

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