In this article we chart baby rats’ care and development 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, trace the milestones of their first weeks, and answer question such as “when do baby rats open their eyes?” and “what do baby rats eat?”
Most importantly, we find out what it takes to turn a baby rat into a happy, friendly pet when they’re grown up.
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.
How many baby rats in a litter?
Rats’ ability to procreate and proliferate is legendary.
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 offspring!
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, and even 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.
The first weeks of life are, unsurprisingly then, packed full of big changes, rapid physical development, and break-neck learning curves.
It’s a fascinating journey from helpless newborn to self-sufficient grown up, so let take a look at it week by week.
Baby rats – week one
Pigment will start 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: limited to lifting their head, and wriggling back back onto their tummy if they find themselves the wrong way up.
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 litter mates.
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 together 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.
By clumping together in a rat pile with their brothers and sisters, a litter of rat babies can reduce how much of their surface area is exposed to the air, preventing heat loss.
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, which they can invest in other things instead (like growing!).
Baby rats – week two
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.
And 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.
Once the ear canal opens on day twelve, things start to sound much clearer.
Baby rats 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?
Baby rats use ultrasonic vocalizations from an early age to tell their Mom when they’re cold, hungry, or lonely.
These noises are way outside of our hearing range, but easily audible to an adult rat.
Bear this in mind if you ever disturb a baby rat nest – just because you can’t hear them protesting doesn’t mean they’re not!
Baby rats – week three
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 of taste and smell, which has been slowly developing since birth, is nearly complete.
And in 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 18 days old.
Orphaned rat pups can be raised on formula, with help and advice from a vet.
On day 18, baby rats 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 softened in a little formula.
These foods don’t take over from their mother’s milk overnight though – they’ll continue to suckle from her for a few more weeks yet.
When do baby rats open their eyes?
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.
Baby rats usually finally open their eyes on around 15 after being born.
Now they can see properly, although it might not feel that way to us – their eyesight is much poorer than ours.
But interestingly their visual angle is far wider, and includes the area above their heads as well as in front of them and to the sides!
Baby rats – week four
As our typical rat litter enter their fourth week on earth, they are about to hit the absolute pinnacle of being cute baby rats.
They are an intrepid bundle of energy, itching to explore, and if you can visit them, or solicit a photo of them from your breeder at this age, do it!
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.
Most importantly of all, they’ll be nursing less and less from Mom, and she’ll be encouraging that by spending more time away from the nest.
Baby rats – week five
Our rat pups have been getting used to solid food for a week or so, and 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 week six.
But before we get to that, week five is a vital age for a baby rat’s social skills, and let’s find out why.
Baby rat development: learning to get along
Playing with their litter mates is a vital part of a rat kitten’s social development.
Rats should always be kept in pairs or larger groups throughout their lifetime.
Lack of company and interaction with another rat is hugely stressful for them.
But 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.
Responsible breeders will always make sure baby rat have company growing up, so they are confident and friendly as adults.
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 rats – week six
Back to our typical litter one last time, and at last our baby rats are six weeks old, which means they’re ready to leave their mother and go to a new home.
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).
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.
You’ll get to watch as they stop acting like babies, and their grown-up personalities cement themselves.
It’s going to be a lot of fun!
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.
Their first six weeks of life are a rapid period of development, when 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.
Have you raised baby rats?
Have you ever had a litter of cute baby rats at home?
What were the highlights of their first few weeks?
Tell us all about it in the comments section below!