Breeding Mice - The Basics

From Mating to Weaning Mouse Gets Babies

The idea of having babies from your mouse has crossed the mind of many owners of female mice. However, breeding babies requires more or less time and effort from the mouse owner. Therefore, there is a long way from momentary impulse to the day when babies have been separated from the mother and have found a new, good home. Breeding mice is very interesting and following the babies' growth from pink, hairless little things to lively young mice is great. That is - provided that the future mouse mother and the owner are well prepared for things to come.

Your Female

The first thing to consider is, if your female mouse is suitable for having young.

It has to be of suitable age, not too young or too old to be mated for the first time (3-6 mo old). It is very important that your female does not have any inheritable diseases or defects, which she could pass on to her young. These kind of defects are among others inheritable kinked tail - not one caused by an accident. It doesn't seem to be a reason big enough to leave a mouse out of breeding, but even though the mouse does not suffer from slightly kinked tail herself, her babies may have severe kinks in the spine, which causes the poor mouse great suffering. For this reason it is better not to use a mouse with a kinked tail for breeding.

Other severe, apparently inheritable defects are ones concerning central nervous systems. These can be seen as for example involuntary jumping to the tank's ceiling, dancing, and problems with balance. It also may be connected to troubles within the central nervous system when a mouse bites off its cagemates' whiskers. You should not use a mouse like this for breeding, as whisker biting is probably inherited. You should also separate a whisker biter form other mice, as they do suffer from the loss of whiskers. Mouse without whiskers will also be disqualified in shows. You can spot the whisker biter from a group of mice by the fact that its own whiskers are intact.

Several faults in coloring are inherited strongly and they can appear after many generations. This should be considered carefully if you plan to breed mice with the intention of showing them. These kind of faults are white tail tip and white feet on a dark-coloured mouse. These faults are very hard to breed out of a strain and a white tail-tip will stop an otherwise perfect mouse's show career.

If your breeding mice have bad faults in coloring, it is better not to use them for breeding. If you are really interested in breeding, it is far better to obtain proper, suitable breeding mice than to use mice with faults. Getting a good, sensible breeding mouse / mice should not be too much of a financial strain to you. This way, you will also have a much better start for your breeding. If you decide to continue breeding, getting white tail tips into a strain you have worked hard with will surely annoy you. In addition to you, it will annoy anyone who uses mice bred by you for their own future breeding with unpleasant consequences.

The Father

If the planned mother is OK, the next thing is to find a suitable father candidate.

The male must naturally also be free from above-mentioned faults and defects. When planning a? mating, you should also take good care that the male will also correct some possible "weak sides" on the female. For example, if the female's coloring is a bit too dark, use a lighter male, if your female has small ears, choose a beautifully big-eared male to be the future father of the baby's etc.

If you do not own a suitable male yourself, you have to borrow one. You should also borrow a male if your own male isn't the best possible choice. You can ask for a breeding male from a list of breeding males available (these kind of lists are available at some mouse clubs) or from breeders of the breed the colors you are interested in. You should also visit shows as you can find a suitable male there and you can see the male right away. Mating arrangements, the fee you should pay and other aspects of using someone else's male for breeding you naturally have to discuss with the owner of the male.

The Mating

Usually the female moves in with the male for mating. On this occasion, the owner of the female should contact the owner of the male 1? - 2 weeks after the agreed date for mating. By this time it is usually apparent if the female is pregnant or not. If the female has already a rounder appearance, it is time to head back home. You should not transport, pick up or otherwise disturb a female during the last days of her pregnancy in order to avoid miscarriage or hurting the babies.

If you mated your female with your own male, this is the point (at 1? -2 weeks after mating) when the male should be separated from the female. Otherwise the male will mate with the female again directly after her giving birth, which will result with another litter being born three weeks later.

When Your Female is Pregnant

When the female is pregnant, you have to take good care of her diet and basic care. The diet have to be versatile enough: in addition to green food you should give porridges, vegetables or fruit, dry dog or cat food to fill up the need for protein, among others. You can add multivitamin solutions to the drinking water and add pulverized calcium to the food. Give as much food as your mouse will eat. Her terrarium should be provided with lots of beddings and hay or shredded paper for building nests and possibly a nest box, preferably one you can open. You should clean the terrarium a few days before the calculated date of giving birth. However, do not disturb the nest your mouse has build with lots of effort.

Some breeders let two females to live together while one or even both are pregnant. Some females are excellent midwives, but it may not be a good idea to try this arrangement with your mice. There have been reports on the other female (not the mother) stealing all babies and starving them due to not having milk, of females fighting over babies and such. When two females have their litters together, provide them with only one nest - two may result with fights. Note, that if your females and their babies are of similar colors, you may not be able to tell apart which babies are whose.


Many females get considerably rounder before giving girth, some not so much, but you know that giving birth is near when the female's belly starts to get "lumpy" - especially if there are lots of babies. The female will usually give birth about 19-21 days after mating. You know that the babies have arrived when the female is suddenly slim and you can hear the babies chirping from inside the nest. Especially a first-time mother may be very nervous, so you should not disturb the nest during the first days of the babies' lives. When disturbed, the mother may even eat her young in her distress. If you have to check the nest, for example to see if there are any dead babies there, you have to first remove the mother when she voluntarily comes out of the nest. After this, carefully lift the nest materials with a long q-tip, which has been first rubbed in the beddings of the tank in order to remove strange smells. You can also get a hint how many babies there are: are there two or twenty, The size of the litter depends on the strain of the female mouse, usually there are 7-10 babies, but nearly 20 babies isn't that rare.

You should change the beddings very carefully, changing mainly beddings from the potty corner of the tank, this way avoiding disturbing the mother.

The Babies Grow...

When the babies are about 6-9 days of age, their coats start to grow. If the mother is calm, you can already touch the babies after first removing the mother from the tank. You can carefully stroke the babies for a little while once a day, after handling the beddings in the tank in order to avoid strange smells. Gentle handling at this age makes it easier to tame the babies and to get them to know people.

At 12-15 days the babies' eyes will open and they start the leave the nest, at first only for a little time. For a while the mother tries to carry the babies back to the nest, but soon she realizes that there's no use with that. Little by little the babies start to eat solid food and the mother stops nursing them. However, you should not separate the babies from the mother before they are four weeks of age. You should not let the babies go to new homes before they are at least a month old. At the time of weaning, separate the male and the female babies from each others in order to avoid troubles. There have been cases when a less than five-week-old male has mated with his sisters. You can leave the female babies to live with the mother, though. You should also separate the males into single mouse tanks a few weeks after weaning to avoid them fighting with each others.

If you do not plan to keep all the babies to yourself, please take care that they end up in good homes. If you decide to take them into a pet shop, check carefully that the shop is a very good one and that they take good care of their animals there. If the your baby mice are the first mice to the new owners, you have to provide them with plenty of information; on care, feeding, clubs and such. In this case, the information the breeder (that means you!) can give, is vital.

Text by: Carita Gunnar. Additions by Satu Karhumaa.