American Fancy Rat & Mouse Association

This article is from the Holiday 1998 AFRMA Rat & Mouse Tales news-magazine.

Breeding & Stuff

World Record Mouse Litter?; No Rat Babies After 4 Months
World Record Mouse Litter?

QI was wondering if my pet mouse set a world record or anything because she had 14 babies in one litter. I thought they normally only have 1–7 babies in one litter. Mine had double the normal rate. I looked in the Guinness book of world records but it said nothing, so I was wondering if you knew. The babies are doing great, but the mother has her hands full because she has 14 newborns and she had one baby 2 weeks ago. I guess that the mouse she shares a cage with is a male. As soon as she is through nursing her babies, I am going to separate the males from females to prevent this from happening again. The daddy mouse has been bringing food into their nest for the mom so that she won’t have to leave the nest, but occasionally she has to leave to get water.

AActually, 14 babies isn’t all that unusual for a mom mouse; 8–12 is the average, but I hear of 14 or more fairly often. I actually had one mouse that had 21 babies! While 14 isn’t unusual, it does put a lot of stress on the mom mouse to feed all those hungry little ones as she can only feed 10 at a time. You may want to make sure to supplement her diet with some fresh fruits or vegetables, and possibly a small amount of whole wheat bread and a couple pieces of dry dog food each day. It will help her keep her strength up.

Unfortunately, you are likely to find that your female mouse will have another litter of babies when these are 3 weeks old. Male mice can breed with the female immediately after she gives birth to the litter, so she is probably already pregnant again. If you leave the male in with the female, you can expect 8–12 babies every 3 weeks, which is very stressful on the mother mouse. I would suggest removing the male now, so you don’t end up with more babies.

Another thing to keep in mind is that you will not be able to keep all the male babies together for very long. When the males are about 2 months old they will usually begin fighting (there are exceptions, but they are rare). You might want to begin looking for homes for your babies as soon as possible. Nichole Royer

No Rat Babies After 4 Months

From our files
QI’ve had my male rat, Topaz, with two females for 4 months now and still no litters. This happened with other rats and mice of mine, too. Any suggestions?

AHow old are the females you are trying to breed? You should start breeding rats at 4–6 months. If you wait too long, then you may run into problems getting the female bred or the possibility of her having problems delivering the litter. Mice should be bred for the first time at 2–4 months of age. I would suggest trying young females that are 3 or 4 months old. It’s always possible that the problem is the male and your male is sterile. Also, if a female has had babies and you wait too long to breed her back, you may run into problems. *

May 31, 2014