What to Do When Your Pet Mouse Has Babies
One day you wake up and notice your pet mouse looks like she swallowed a golf ball. If you hadn't figured it out over the last week and a half, she's pregnant. If you've never gone through this before, it can cause a mild panic.
"I'm not ready to be a parent!"
"I don't know how to take care of baby mice!"
"That's just three to fourteen more mouths to feed!"
While it feels overwhelming, taking care of baby mice doesn't have to be difficult. In fact, for the most part, you should just sit back and let mom do the work. If you keep a cool head, you may not even feel like you have extra mice to worry about at all.
I bought a mouse who later showed signs of pregnancy. I turned to the internet—as I'm almost certain you have as well—but couldn't find an organized list of what to do. You'll find great tips scattered here and there, but I thought it would help to collect them all and provide them to you in one convenient location.
Hopefully, you'll notice the pregnancy before your pet gives birth. That gives you some time to prepare the preliminaries:
What to Do if Your Pet Mouse Is Pregnant
- Decide How Many Children You Are Willing To Keep
- Decide What to Do With Mom's Cagemates
- Clean the Cage One Last Time
1. Decide How Many Children You Are Willing To Keep
If your mouse's litter is large, you may end up wanting to rehome some of the baby mice. We got lucky. Our mouse, Rinoa, gave birth to a litter of only three. When mice get pregnant young (six weeks or so), they don't have as many children. The ones who wait until full adulthood can have larger litters, so you may be stuck with a pile of mice. The babies can be cute, but don't become an animal hoarder--if you have too many pets, all of the animals suffer from divided attention from you and high stress due to a crowded living space.
You probably need to rehome them. They should stay with their mother for four to six weeks--at the very least until they begin eating solid food. Once they can, you can start posting ads. Local pet stores may offer space for a flier, and some will even offer to take them in. If so, that solves your problem (unless you object to euthanasia for unsold pet mice). Otherwise, Craigslist may give you the best exposure. It's an unfortunate and frustrating method of handling the situation, but if you can't offer pet mice to an interested friend, it may be your only option.
2. Decide What to Do With Mom's Cagemates
Your pet likely has cagemates (at the very least she had one, probably about three weeks ago). Not all of them have to go, but choosing which mice may help care for children and which mice may harm them could prevent a potential cannibalism or castration.
Male mice definitely need to go. I often compare mouse psychology to human psychology, but one notable difference between species rests with the fathers' role in caring for the kids. Male mice couldn't care less (whereas MOST human fathers will take some responsibility). Mom will protect her children fiercely, and could do serious damage if she feels dad--or any other male mouse--might harm her family.
Honestly, though, you really only want boys and girls to share a cage if you intend to breed them. So at most, you should only have the father and whichever other females in the cage. Take him out, and sources say not to put him back with other males once he's mated. I can't offer an opinion on this, since I never bred mice and didn't buy the father along with the mother.
Females can stay—or so we've been told. Often times, girls will help their friends take care of children. In a pet store, I once saw one bring food to the nest while the mother fed the kids. We didn't know whether to risk this or not. We trusted our sources, but the other mouse was only about three or four weeks old herself. Still a child, we opted to put her in her own cage. I'm sad to report that she appears withdrawn and depressed, but whenever we tried introducing her to Rinoa and the babies, Rinoa chased her around trying to scare her off.
The two of them get along fine if we put them on neutral ground (not in one of their cages) and leave the babies in the nest. Hopefully I'll have more information on this later.
3. Clean the Cage One Last Time
Once the kids are born, you'll want to leave the cage untouched for a few weeks. As soon as you see mom in her golf-ball stage, get the cage ready. Clean it thoroughly. Line the bottom with baking soda and layer the bedding extra thick--you should be using corn cob. While it costs more than other types of bedding, it's cleaner, healthier for the mice, and it will keep the room from stinking for a longer time.
Put mom back in. You probably destroyed her nest, so give her materials to build a new one. She also would appreciate a safe, dark place to build. We put in a kleenex box with one side cut out (laid it on the cut-out side and let the mice go in and out through the slot for the tissue). Other household boxes work just as well. Make sure the floor gives her access to the bedding, though.
1. Pinkie Mice
From the moment they're born, we call them pinkie mice. If you catch a glimpse of them, you'll understand. Without fur, they look like pink, wriggly little things. You should try to catch sight of all the children--if possible, but don't reach into the cage--to check their health (I can't tell you what to do with stillborn pinkies. All three of ours had perfect health). Listen for chirping. This also lets you know they're safe.
You have a light work load here: give mom extra food and keep away from the cage as much as possible. I read that if mothers feel threatened, they will cannibalize their children for their own good. I can't presume to know what rationale a mouse may use to lead her to snack on her kids like popcorn, but the first part of that statement may ring true. Don't hover near the cage or stare for too long. You want the mice to feel safe.
Rinoa, skittish and nervous since we bought her, suddenly became affectionate and curious. She approached us during this stage and often stepped on our hands or climbed out of the cage herself.
**This may be why the method I describe here works: An amenable mom could be much easier than a constantly frightened one. Please exercise caution if you own the latter.**
As long as she's willing, you can handle the mother and play with her as usual during this time.
2. Their Fur Starts to Grow In
After roughly five days or so, the pinkies will become less pink, and you can start to see their coloring and marking. At this time, you should start handling them for short periods of time. Exercise caution if the mother seems nervous. We always sat on the bed and let mom roam free, allowing her access to the kids.
Try to keep the babies together and try to keep them warm. You'll often see pinkie mice trying to squeeze underneath the others--they need more heat than adolescent mice. Don't spend too much time with them.
When you put them back, get mom into the cage, then hold out the children on your hands next to the nest. Give the mother the option of moving her kids by herself--this, I'm told, makes her less nervous because she has control.
Repeat this daily.
3. Their Eyes Open
The babies probably won't leave the nest for at least another seven to twelve days. It all depends on when their eyes open. Once they can see, their exploratory instincts kick in and they want to inspect everything in the world. Rinoa didn't do this, but some mothers will forcibly drag them back to the nest.
Young mice move fast. Daily handling should make your scent familiar, but keep an eye on them anyway.
4. Flea Stage
This point in their development also goes by the term "popcorn stage," but after the cannibalism comment I made about popcorn, I think I should use "flea" instead.
You can safely consider them toddler mice at this point. Human children go through a phase where they learn to coordinate their motor skills. In mice, this manifests as jerky movements and a lot of jumping around like fleas. They also begin climbing.
If you haven't done so already, check the bars of the cage. One of our cages has bars about 1.3 cm apart, while the cage we keep the kids in only spaces them 0.5 cm apart. Mice in the flea stage can crawl through the 1.3 cm openings. In fact, early this morning I heard panicked squeaking and woke up to find one of them had crawled out of her own cage and into the cage we keep our anti-social male mouse.
Inspect your cage--even if the bars are close together. I found that one of the latches had an opening big enough for a mouse to crawl through. Inspect your cage carefully and make sure you don't find any secret exits that a tiny little mammal might find exciting and adventurous.
**Please use cages with bars. Glass aquariums repress their instinct to climb. You can make your mice happier by letting them use the walls and ceiling of the cage in addition to the floor space.**
During this stage, we witnessed our mice start to climb into the food dish and drink from the water bottle. This signifies the weaning process has begun. The kids slowly stop relying on their mother for milk and start eating solid food.
5. Lifting Tails
At the end of the flea stage and weaning, you can treat mice the same way you treat adults. Give them attention. Let them run on a wheel. Put interesting things in their cage for them to explore and climb.
Also, before six weeks, you may want to separate the girls from the boys--unless you want to go through all this again, except the baby mice will have two tails. It takes a master to determine their gender. The best we can do is guess--lift up their tails if you get a chance. You'll see the same thing on both boy and girl mice--a small hole underneath the tale (which will be how they leave you presents in the future) and a little knob a short way down. The knob looks slightly different depending on the gender, but the better indicator is that the distance between these anatomical features will be shorter on female mice.
But even experts misidentify gender sometimes. You can positively identify older mice--if it looks like they're dragging a grape behind them, you've got a boy--but by that point, it may be too late. I'm sorry. I wish I could tell you more.
What Comes Next?
Once finished with this month and a half of special care, the mice can live independently of their mother. If you plan to keep them, make sure you have enough cage space--one average sized cage per two mice--and if you keep the males, don't separate them or they'll more likely fight when they get older (at which point you can read my article on the alpha mouse). Fliers, pet stores, and friends are still the best options for the mice you can't keep. Craigslist is sketchy, but it offers exposure.
Otherwise, have fun with your new rodent friends.
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.