Rats are prolific breeders that can give birth to large litters of baby rats called pups. Newborn baby rats have a unique appearance that changes as they grow. Knowing what to expect can help you identify baby rats.
What does a newborn baby rat look like?
Newborn baby rats are tiny, weighing only around 5 to 7 grams. They are born hairless, with their eyes and ears closed. Their skin is pink in color.
At birth, baby rats cannot regulate their own body temperature. They rely on huddling together in a pile with their littermates and being kept warm by their mother.
Newborn rats have short hind legs and stubby, fewer-digit forepaws. Their tails are about the same length as their bodies.
Baby rats nurse constantly at first, attaching to their mother’s nipples. They make high-pitched squeaking noises to communicate.
When do baby rats open their eyes and ears?
Baby rats are born with sealed eyes and ear canals. Around 2 weeks of age, their eyes and ears start to open:
- Eyes open between 14-18 days old
- Ears open at around 18 days old
At first, baby rats can only detect light and shadows. Their eyes will be blue-gray and cloudy looking. Vision improves over the next week.
Hearing develops more slowly. The ear canals open but it takes additional time for hearing ability to fully mature.
When do baby rats get fur?
Baby rats start to grow fine, downy fur at around 2 weeks old. The fur continues filling in over the next several weeks.
Fur usually comes in this order:
- Light fur around the nose, mouth, toes, and tail (2 weeks)
- Dark fur along the back (3 weeks)
- Fur fills out over body, head, limbs (4-5 weeks)
- Coat thickens as guard hairs grow (5-6 weeks)
Baby rats may look patchy or scruffy until their adult coats grow in more fully by 6-8 weeks old.
When can baby rats eat solid food?
Baby rats are entirely dependent on their mother’s milk for the first 2 weeks. Around 3 weeks old, they start sampling solid foods by nibbling on their mother’s regular diet.
Between 3-5 weeks is an important transition period when baby rats begin eating more solid foods but still nurse sometimes. By 6 weeks old they are typically weaned off milk entirely.
Some key milestones in baby rat weaning:
| Age | Diet |
|---|---|
| 2 weeks | Nursing only |
| 3 weeks | Sample some solids |
| 4 weeks | Eat more solids, nurse less |
| 5 weeks | Mostly solid foods, occasional nursing |
| 6+ weeks | Fully weaned onto solid foods |
When can baby rats leave the nest?
Baby rats grow rapidly and reach some important physical milestones in their first weeks:
- Open eyes – 2 weeks
- Open ears – 3 weeks
- Begin eating solids – 3 weeks
- Fur coat growing in – 3-5 weeks
Once their eyes open, they become more curious and start to explore outside the nest area while still returning regularly to nurse. They begin venturing further away around 5 weeks old once weaned off milk.
When do baby rats reach full size?
Baby rats grow incredibly fast. Most of their development happens in the first 3 months of life.
Here’s an overview of how quickly baby rats grow:
- Newborn – 5 to 7 grams
- 2 weeks – 30 to 40 grams
- 3 weeks
- 5 weeks – 100 to 120 grams
- 10 weeks – 200 to 300 grams
- 1 year – 300 to 500 grams full adult size
Female rats may reach full adult weight by 12 weeks old. Males often have a longer growth period, filling out to full size by 5-6 months old.
How can you tell male vs female baby rats?
Telling male and female baby rats apart can be tricky but there are some techniques:
- Look at the gap between genitals and anus – this gap is further apart on male babies
- Check distance between nipples – females have closer nipple spacing
- Compare body shape – females tend to be sleeker while males are blockier through the head and rump
- Examine ears and paws – males tend to have larger ears and wider paws
While these clues can help, even experienced breeders can struggle to accurately sex baby rats younger than 3-4 weeks old. The best confirmation comes when the testicles descend in male babies around this time.
How many babies do rats have?
The average litter size for rats is 6-12 pups, but litters can vary from as few as 2 to as many as 20 babies. Litter size depends on factors like the mother’s age and how many times she has given birth before.
Key points about rat litter size:
- First-time rat mothers usually have smaller litters of 4-6.
- Experienced mothers can have 10+ babies.
- Wild rat litters tend to be larger than pet rat litters.
- Unusually small or large litters do happen.
- The babies may not all survive, averages are based on how many are born alive.
Mother rats have 12 nipples to nurse her babies. Large litters may outgrow the number of available nipples, impacting growth and survival.
Typical litter sizes
| Rat’s Age | Average Litter Size |
|---|---|
| 3-6 months old | 4-6 babies |
| 6-12 months old | 8-12 babies |
| 1-2 years old | 10-14 babies |
How often can rats get pregnant?
Rats can become pregnant again almost immediately after giving birth due to these factors:
- Short 21-24 day gestation period
- Ovulation begins within 24 hours of giving birth
- Can mate and conceive postpartum
- No fertility delay while nursing
As a result, female rats can breed year-round. In ideal conditions, they can produce a new litter every 3 weeks and have 15-20 litters per year.
Intense, continuous breeding is rare outside of rat farms. But it illustrates rats’ potential reproductive capacity.
When are baby rats ready to be separated from mom?
Baby rats should stay with their mother and littermates until at least 5 weeks old. This allows time to nurse and learn rat social behaviors.
Ideally, rats benefit from staying together until 6-8 weeks old before being separated. Some key indicators a baby rat is ready for adoption:
- Weaned from nursing
- Eating solid foods well
- Active, curious, and playful
- No lingering health or growth issues
Separating babies too young leads to health and behavior problems. Always check with your breeder on appropriate timelines.
Do wild baby rats look different?
Baby rats follow the same growth stages whether they are wild or domesticated. But wild rat babies do have some distinguishing features:
- Fur color – Wild rat fur is more brownish vs. domesticated black and white coats.
- Body size – Wild rats are noticeably larger and heavier.
- Snout shape – A longer, pointier snout compared to the blunt snouts of pet rats.
- Ears – Larger ears proportional to the head and body.
- Tail – Longer, thicker tails sometimes with bald patches from rough living conditions.
- Eyes – Smaller, more sunken eyes that are adapted for burrowing.
These differences reflect adaptations wild rats have evolved to aid survival. But baby wild rats still pass all the same growth milestones at a similar pace to domesticated litters.
What do baby rats need?
Caring for baby rats requires keeping them warm, well-fed, and safe. Here are some top things to provide:
- Nest box – With bedding to mimic a burrow environment.
- Mother’s milk – Sole food source for 2+ weeks.
- Supplemental warmth – If mom can’t provide enough on her own.
- Proper nutrition – Balanced diet once weaned off milk.
- Socialization – Daily gentle handling and play.
- Clean habitat – Keep their space free of waste.
- Health monitoring – Watch for issues requiring medical care.
With their rapid growth, baby rats have high demands for nutrients, hydration, appropriate housing, and affection. Meeting these needs allows them to thrive.
What health problems do baby rats have?
Some common health issues seen in newborn and young baby rats include:
Birth defects
- Cleft palate – opening in the roof of the mouth
- Missing or extra toes
- Kinked tail
- Hernias
- Heart or kidney defects
Failure to nurse or thrive
Cause: Small litter size, poor milk supply, low birth weight, birth defects
Respiratory infections
Causes: Viral, bacterial, or fungal infections. Higher risk in large litters.
Diarrhea
Causes: Diet changes, intestinal parasites, infections, antibiotic side effects
Skin problems
Causes: Parasites, ringworm fungus, mites, abrasions from rough play
Catching and quickly treating any health issues improves chances of survival. Providing excellent nursing and nutrition also helps prevent illness.
How to handle and hold baby rats safely
Baby rats are fragile creatures that require gentle care. Here are some tips for safe handling:
- Wash hands before and after to prevent spreading germs.
- Sit or crouch down over a soft surface in case they wriggle free.
- Be very delicate picking them up, with full support under the body.
- Never pick up baby rats by their tails.
- Hold them close against your warm body or in cupped hands.
- Keep handling sessions short, ideally 5 minutes or less.
- Return them to the nest if they seem stressed or get very active.
Daily brief handling helps socialize baby rats. But they still need lots of sleep and mom time in the first weeks of rapid growth.
Tips for caring for orphaned baby rats
Baby rats orphaned before weaning require round-the-clock care. Here are some tips if you end up bottle-feeding rat pups:
- Use kitten or puppy formula – not cow’s milk.
- Feed every 2-3 hours using an eyedropper or small syringe.
- Gently massage their abdomen after eating to help digestion.
- Keep babies warm using a heating pad, microwavable rice bag, or your body heat.
- Stimulate to urinate and defecate as the mother would.
- If possible, put rats with a nursing mother who can adopt them.
Raising orphaned rat babies is very challenging. Always seek advice from an exotics vet on nutrition and care.
Conclusion
Baby rats are born hairless and helpless but transform incredibly fast. Within weeks they open their eyes, grow fur, start eating solid food, and become miniature versions of adult rats. Providing attentive maternal care and proper weaning helps ensure baby rats grow into healthy, well-socialized companions.