Breeding Mice

Thinking about breeding mice?

Here's a list of things to know before you pair your buck and doe:

⚠️ WARNING: Graphic Language, Animal Death, and Cannibalism⚠️ 

If not, you risk your doe getting pregnant immediately after giving birth. This means you will have another litter in 3 weeks, before the current is old enough to be weaned. This can jeopardize the health of the dam, and both litters, and can lead to death. This can be considered animal neglect.

Worst case scenario, your doe can pass away from birthing complications. If there are complications, she may also need to be put down. Aside from giving your dam a peaceful death, there is little else you can do is this situation.
For a variety of reasons, dams may also kill and possibly eat their litters. This is a natural response to stress and malnutrition. If a doe is too stressed, she will abandon the litter and consume it to regain valuable calories. If your doe is not able to properly feed her litter, this can also cause her to reduce the litter to some extent, or entirely.

If your doe is too young to breed, she can have complications. Most pet store mice are 3-5 weeks old when they are sold. Does should be bred no sooner than 8 weeks, with some needing 12 weeks. She may also know she is not yet mature enough to raise the litter, and abandon them, and likely consume them after doing so.

While it is uncommon, litters of all does or all bucks are possible. If you have males in a litter, they need to be removed by 4 weeks unless they start fighting earlier. Usually young males can be fine together until 4-8 weeks of age, but mature males can fight and kill each other. For this reason. housing males together is not a long term solution.

If your cage is not big enough to fully raise a litter in, it can cause the litter to produce too much ammonia too quickly. If the cage is not cleaned often enough, this can cause the mice to develop lung infections, and possibly lead to death.

Culling a litter down means to reduce the size. If you do not do so, the litter may be too big for the dam to properly take care of. This can lead to her reducing the litter size herself, or killing the entire litter due to stress. If she does not, then she can become sickly from trying to keep up with the milk demand, and possibly pass away. Some does may survive large litters, but at a severe loss of body condition.

Keep in mind that this list is not meant to discourage those fully prepared to start breeding. It was simply created as a reality check in case someone hadn't come across such blunt information about the ups and downs of breeding mice. It's definitely not for everyone, and it can be extremely hard on pet owners who don't know what they are getting themselves and their pets into. Hopefully this will help you decide.

Want to talk to other experienced mouse breeders? Here is a list of Facebook groups:

Fancy Mouse Breeders' Association

Practical Rodent Breeding