In this article we chart baby rat care and development. We’re covering the time right from the day they’re born until they’re ready to come home and start a new life in your family. We’ll find out what newborn baby rats are like and trace the milestones of their first weeks. By the end of this article, you should know how to care for baby rats.
Also, we’ll answer questions such as “when do baby rats open their eyes?” and “what do baby rats eat?” Most importantly, though, we find out what it takes to turn a baby rat into a happy, friendly pet when they’re grown up.
So, if you’re a new rat owner, welcome on board! Let’s start right at the beginning.
What Is a Baby Rat Called?
A baby rat is called a kitten or a pup. You can use whichever name you prefer, or both interchangeably if you’re as indecisive as me!
As a general rule of thumb, a rat is a pup (or kitten) until they have finished weaning. Then their babyhood ends and they’re ready for adult life in a new home!
We’ll find out what age they usually reach that point a bit later on. But here’s another popular question about these rats.
How Many Baby Rats in a Litter?
The average rat litter size for wild baby rats is four to eight pups. Healthy, well cared-for pet rats usually have litter sizes at the top end of this range, or even higher.
Mother rats have 12 nipples (more than dogs, cats or mice), so they’re well equipped to juggle lots of newborn baby rats! At least you don’t have to worry what to feed pups.
How Often Do Rats Have Babies?
Rats’ ability to procreate and proliferate is legendary. Female rats produce up to 12 litters per year! Plus, these females can begin to bear children as early as when they’re 5 weeks old. Amazingly, rats only need to gestate for 21-23 days before they’re ready to birth 6-12 newborn baby rats.
As they get older, breeding does slow down.
What Does a Baby Rat Look Like?
On the day they’re born, rat pups are small enough to fit on a teaspoon.
Their eyes are tightly sealed, and their ears are stuck flat against the side of their head.
Their tail is much shorter relative to their overall body length than that of a full-grown rat.
They have baby teeth and whiskers, but no fur or pigment in their skin, so they appear bright pink.
And their skin is so thin and translucent that you can see the shape of their eyeballs behind the lids. You can even see the milk in their tummies after they’ve fed from mother!
Baby Rats Week by Week
As you can tell, newborn baby rats have a lot of catching up to do before they’re ready to leave their Mom.
Unsurprisingly then, the first weeks of life are packed full of big changes. They experience rapid physical development and break-neck learning curves.
It’s a fascinating journey from helpless newborn to self-sufficient grown up, so let’s take a look at it — baby rats week by week.
Baby Rats – Week One
Pigment starts to accumulate in their skin almost immediately after birth. But it won’t be until day five that they begin to get their first peachy fuzz of hair.
And until they’re four or five days old, a rat pup is pretty much immobile. They’re limited to lifting their head and wriggling back back onto their tummy if they find themselves the wrong way up.
Still, without sight or hearing to guide them, newborn baby rats can already use their whiskers to find their mother’s nipple, and form a huddle with their littermates.
Huddling – the Classic Image of Cute Baby Rats
Peek inside a nest of baby rats, and you’re unlikely to be able to tell where one pup ends, and the next begins.
This huddling is adorable sight, and it serves an important purpose too. Without fur, baby rats quickly lose heat from their skin when it’s exposed to the air. So by clumping together in a rat pile with their brothers and sisters, they can prevent heat loss. This is because huddling reduces how much of their surface area is exposed to the air.
In fact, in 1978, animal behavior expert Dr Jeffery Alberts at Indiana University discovered that a litter of rat pups will expand and contract the size of their huddle depending on the ambient temperature, to make sure they always feel just right!
And by doing this, they use up less energy keeping warm. They can then invest this energy in other things instead (like growing!).
Let’s rejoin our typical rat litter in their second week after being born.
Their baby coat of fur is coming along nicely, and they can just about push themselves up to standing.
By the end of the week they might even be taking their first steps.
But another big change is afoot for them. Around day ten, the outer ear stops being flattened against the side of the head, and on day twelve, the ear canal finally opens.
What Can Baby Rats Hear?
When they’re born, baby rats’ ear canals are sealed shut. That doesn’t mean they’re completely deaf, but things are definitely muffled. So, once the ear canal opens on day twelve, things start to sound much clearer.
Rat pups can make out low frequency sounds first, and then gradually higher frequencies, until eventually they can hear everything between 200Hz and 90,000Hz.
Compare that to our hearing range of 16 – 20,000Hz, and they’ve really got us licked!
What Do Baby Rats Sound Like?
So we know what they can hear, but what sounds are they making themselves?
Rat pups use ultrasonic vocalizations from an early age to tell their Mom when they’re cold, hungry, or lonely.
These noises — which sound like baby rat squeaking — are way outside of our hearing range. However, they’re easily audible to an adult rat. This is quite an important part of baby rat behavior.
Bear this in mind if you ever disturb a rat pup nest. Just because you can’t hear them protesting doesn’t mean they’re not! And if you do hear baby rat squeaking, you know to get away.
Back to our typical litter, and our rat pups are growing fast. At the beginning of their third week, they should have more than quadrupled their birth weight.
Their sense of taste and smell, which has been slowly developing since birth, is nearly complete. And this week, their eyes will finally open!
So obviously we’re going to look at both those milestones in a bit more detail.
What Do Baby Rats Eat?
Baby rats need nothing more than their mother’s milk to thrive until they’re about 21 days old.
Orphaned rat pups can be raised on formula, with help and advice from a vet.
On day 21, they’re are ready to try their first solid foods. They usually begin with something soft and easy, like yoghurt, ripe banana, or their mother’s usual rat pellets. You can soften these in a little formula.
These foods don’t take over from their mother’s milk overnight though; this is only the beginning of weaning. They’ll continue to suckle from their mother for a few more weeks yet.
When Do Baby Rats Open Their Eyes? – Baby Rat Behavior
Even when their eyelids are sealed, newborn rats’ eyes are already sensitive to light.
If you suddenly let light into their nest, you’ll see that they turn their heads from the light as best they can, depending on their stage of development.
They usually finally open their eyes on around day 15 after being born.
Now they can see properly, although it might not feel that way to us. This is because their eyesight is much poorer than ours.
But interestingly their visual angle is far wider. It even includes the area above their heads as well as in front of them and to the sides!
As our typical rat litter enter their fourth week on earth, they are about to hit the absolute pinnacle of being cute baby rats. By the end of this week their wobbly baby steps will be confident and coordinated. And their velvety baby coat will start to be replaced with distinct guard hairs and under hairs.
They are an intrepid bundle of energy, itching to explore! So if you can visit them, or solicit a photo of them from your breeder at this age, do it!
Most importantly, however, they’ll be nursing less and less from Mom. Interestingly, Mom will be encouraging that by spending more time away from the nest.
Our rat pups have been getting used to solid food for a week or so now. Finally, in week five, most of their energy comes from solid food rather than milk.
They’re also spending an increasing amount of time grooming, digging, play-fighting, and generally asserting their independence.
At the end of this week the male and female pups should be separated, ready for the onset of sexual maturity in weeks five to six.
But before we get to that, week five is a vital age for a baby rat’s social skills. Let’s find out why.
Socialization: Learning to Get Along
Rats should always be kept in pairs or larger groups throughout their lifetime. Playing with their littermates is a vital part of a rat kitten’s social development. The lack of company and interaction with another rat is hugely stressful for them.
This is largely because rat pups kept in isolation growing up don’t learn the social skills they need to live peacefully alongside other rats when they’re grown up.
So, responsible breeders will always make sure baby rat have company growing up. That way, they’re confident and friendly as adults. This truly makes a difference with baby rats behavior as they get older.
It sounds simple, but part of this is making sure that if a male baby rat is the only boy in a litter of sisters, he won’t be deprived of company when it’s time to separate the sexes.
A good rat breeder has a lot to think about!
Baby Rat Behavior – Week Six
Back to our typical litter one last time. At last our baby rats are six weeks old, which means they’re ready to leave their mother and go to a new home. They’ve put away much of their baby rat behavior and are adult rats ready for a new adventure.
It’s been a roller coaster ride for their breeder getting them this far, but their adult adventure is only just about to begin. They’ve already increased their birth weight as many times over! But they’ve still got lots of growing to do.
Pop a six week old rat on the scales when you get home, and take a photo of them with something you can use for scale (my personal favorite is a coffee cup). Then, every month do it again, and see how they compare!
Between six and eight weeks old, your new rat will also go through the ratty equivalent of puberty and adolescence.
So, you’ll get to watch as they stop acting like babies. Eventually, their grown-up personalities will cement themselves.
It’s going to be a lot of fun!
How Long Do Baby Rats Stay With Their Mothers?
Six weeks, typically. This includes the period of nursing the pups and their eventual weaning at about 5 weeks (21 days).
Many people wonder specifically about this, especially when they find orphaned baby rats. What should you do when you find orphaned baby rats? How do you feed them? As mentioned earlier, where the mother is unavailable to breastfeed, you may feed baby rats formula. Just be sure to get assistance from your vet.
How to Care for Baby Rats
Knowing how to care for baby rats is an important part of being a rat owner. There are four main aspects of caring for baby rats. They are:
- Finding appropriate housing: If you live in a home — especially if you have other pets — you likely want to keep your baby rats safe. You’ll want to buy them a cage (experts recommend 2.5 cubic feet (0.07 cubic meters) for one rat). The cage should be a wire one with at least half inch openings between bars. Don’t forget to set up other things like bedding, litter, tunnels, and enough room for your rat to play.
- Caring for their health: Early days are crucial for ensuring pet health, so we’d recommend taking your rat to a vet as soon as possible. Once the preliminary visits are done, it’s recommended that you visit every six months.
- Socializing: To make your baby rat comfortable, be sure to get them another rat friend or littermate. For your part, be gentle with your rat — handle them carefully and, of course, use positive reinforcement. Treats always work better than punishment.
- Feeding baby rats: Baby rats only need milk or formula to survive. Once your rat is weaned, you’ll need to figure out the best way to feed them using a suitable rat pellet.
Let’s now consider this aspect of rat pup care in more detail.
What to Feed Baby Rats — Can Baby Rats Drink Cow’s Milk?
No, cow’s milk is not recommended for baby rats. It does not contain enough useful nutrients for your rat. However, evaporated milk has been used for baby rats with success. If their mother’s milk is unavailable and you cannot find a surrogate rat mom, stick to formula until they’re of weaning age.
Note that after feeding your baby rat, you’ll need to rub their bellies with a warm, damp cloth. This helps with their digestion and helps them to pee when they’re still very young.
Raising and Caring for Baby Rats
So to sum up, rat babies are born tiny and weak, with no fur, and their eyes and ears tightly sealed. We’ve considered baby rats week by week, what to feed baby rats, and more.
Their first six weeks of life are a rapid period of development. This knowledge is important for good baby rat care. Their eyes and ears open, they build up strength, and learn how to get along with other rats.
In their first couple of weeks, every aspect of baby rat care and feeding baby rats will be taken care of by their Mom in the nest.
An experienced rat breeder will know when to leave Mom to it, and when to ask a vet if their pups need help.
Baby Rat Care — Have You Raised Baby Rats?
Have you ever had a litter of cute rat pups at home? What were the highlights of their first few weeks? Were you ever concerned as to “when do baby rats open their eyes”?
Tell us all about it in the comments section below!
If you want to read some other interesting guides, check out our article on the Spider Ball Python!
References and Further Reading
- Wikihow. 4 Ways to Care for a Young Rat. Elliot, P. MRCVS
- APA PsycNET. Huddling by rat pups: Group behavioral mechanisms of temperature regulation and energy conservation. Alberts, J. R.
- Johns Hopkins University. Animal Care and Use Committee.
- MERCK Veterinary Manual. Breeding and Reproduction of Rats. Quesenberry, K. E. DVM, MPH, DABVP (Avian); Boschert, K. R. DVM, DACLAM, Washington University
- PubMed. Artal P., Herreros D., T.,P, Muñoz T. C., Green D. G. Retinal Image Quality in the Rodent Eye
- American Fancy Rat and Mouse Association. Caring for Rat & Mouse Orphans. Robbins, K.
This article has been extensively revised for 2019.