American Fancy Rat & Mouse Association

This article is from the Holiday 1997 AFRMA Rat & Mouse Tales news-magazine.

Breeding & Stuff

Breeding Mice

By Nichole Royer

Lynn Lehman
QI have 10 mice, 9 of which are female. I would like to breed a few but am not sure exactly what all is involved. I have always bought my mice at pet shops, but would like to breed a few of my own. I read in a mouse book that the mice should be put in a cage new to all individuals for breeding, but the male was attacking the two females, so I quickly put them back in their cages. Is this normal for the male to attack them? I was also concerned that since these two females are in the same cage as four other sisters and the mother of all of these, that if I did breed only the two, that the others may attack or kill the babies.

ABreeding mice can be fun, but is often frustrating. Everyone has a method that works best for them. This is what seems to work well for me.

When I want to breed a female, I set up a “maternity” aquarium (a 5-gallon tank works well, as does a 10). I then put both the male and female together in it. I have never had the male hurt the female, but sometimes he can be rather rough in his “handling.” Usually, the male pounces on the female, mounts her, and often even grabs the scruff of her neck with his teeth. The female always lets out a squeak each time this happens. This can be rather loud, so much so that one of our members frequently will say, “I heard the mice in the next room eeking last night, so I know babies are on the way.” If this is what you have happening, don’t worry about it, it’s normal. If your male is actually drawing blood, then there is something wrong. I would recommend not breeding him (since he could pass this trait on to his sons) and getting another male.

I leave the male in with the female until she starts to thicken around the middle, usually about 2 weeks. I then return the male to his cage, but leave the female in the maternity cage. On the few occasions I have put the female back into the cage with her “girlfriends,” there have been no problems with the others hurting the babies. I have, however, noticed that it seems to create a lot of stress on the mother mouse, and the babies never do very well. I prefer to leave a single mother mouse in the maternity tank, and let her raise the babies to 4 weeks in peace and quiet. I like to breed only one mouse at a time, that way I don’t have to find so many homes for babies at once. Other people will put two females together (or more in a bigger maternity tank) and let them raise their babies together. This does cause the complication of not knowing whose baby belongs to whom.

When the babies are 4 weeks old, I remove the mother and her female babies and put them in with my other females. The males I can usually leave in the maternity tank for another 2–3 weeks, or until they start fighting. Once they start fighting, they each get their own tank.

Before breeding your mice, there are a few things you should take into consideration. The age of your female is very important. She should be about 3 months old the first time you breed her. At this age she is fully mature and should be able to handle the stress of raising a litter with no problems. If your female is older than 4 months, you may want to consider obtaining another female for breeding purposes. Female mice over the age of 5 months who are then bred for the first time, have a much higher incidence of major difficulties.

Before you breed, you will want to take a good look at your male and your female. Are they healthy? Do they show any signs of chirping, rattling, or sneezing? Are they in robust health, neither fat nor thin? Do they have nice temperaments? All of these things are very important because they have a major impact on how your babies will turn out. It would be very difficult for ill mice to produce healthy babies. If the mother is sick, she very easily can pass it on to her offspring. Resistance to disease is often hereditary, so even your male can have a major impact on the health of your babies. Sick parents make sick babies, so if either parent is questionable, don’t breed. Temperament is also hereditary. Nice mice produce nice babies. Hyper, excitable, jumpy mice produce babies with similar temperaments. If the parents aren’t great pets, the babies won’t be either.

One final (and major) thing to consider BEFORE you breed your mice is what you are going to do with the babies. Keep in mind that often people do not want male mice for pets since they have a very disagreeable odor. Many pet shops only sell mice to feed to reptiles, so if this is unacceptable for you, another option must be found. If no homes can be found, are you prepared to house your baby mice for the rest of their lives? This is something to consider long before you breed your mice. *

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May 27, 2014