The Stages of Rat Development
Learn about the growth stages of pet rats from pinky to senior.
Newborns (0–7 Days) — The Pinky Stage
At birth, baby rats (called “pups”) are blind, deaf, and completely hairless, earning them the nickname “pinkies.” They rely entirely on their mother for warmth and nourishment.
Key traits:
Pink skin, sealed eyelids and ears
Unable to regulate their body temperature
Constantly nursing and sleeping
No fur yet visible
Infants (1–2 Weeks) — The Fuzzies
Around Day 7, fine fur starts growing in. Their ears begin to unfold, and they're more active.
Key traits:
Soft fuzz covers their bodies
Skin pigmentation shows coat color and pattern clearly
Eyes still closed, but ears perk up
Starting to explore briefly
Juveniles (2–4 Weeks) — The Explorers
This is a big milestone: around Day 14, their eyes open! Once that happens, everything changes. They begin to explore, nibble on solid food, and interact with siblings in more complex ways.
Key traits:
Eyes open (typically Day 14–16)
Start grooming, climbing, and roughhousing
Begin tasting solid foods, though still nurse
Fast physical growth and coordination development
Weanlings (4–6 Weeks) — The Social Sponges
Pups are fully furred, eating independently, and can be weaned from mom between 4–5 weeks of age. They’re intensely curious and learn best by watching each other — or their humans.
Key traits:
Weaned from mom, eating solid food entirely
Extremely energetic, playful, and social
Rapid weight gain and muscle development
Begin forming deeper social bonds
Adolescents (6–12 Weeks) — The Wild Teens
Hormonal changes kick in around this time, especially in males. You may notice brief dominance squabbles or bursts of intense activity. They’re growing rapidly and need a lot of stimulation.
Key traits:
Puberty onset (earlier in females, slightly later in males)
Testing boundaries with cage mates
Surging curiosity and physical capability
Starting to establish hierarchy
Young Adults (3–6 Months) — The Settlers
By 3 months, rats begin to settle into their adult personalities. They’re still active, but many slow down slightly compared to their wild adolescent stage.
Key traits:
More mature behavior and habits
Personality traits solidify (cuddle bug, explorer, food hoarder, etc.)
Physically developed, sexually mature
Adults (6–18 Months) — The Prime
This is your rat's “prime.” They've reached full size, and their personalities are predictable and steady. They’re usually calm, confident, and deeply bonded with their cage mates — and you.
Key traits:
Peak physical health and mental sharpness
Consistent behavior and preferences
Enjoy routines, familiar spaces, and trusted people
Seniors (18+ Months) — The Golden Years
Senior rats begin to slow down and sleep more. Common aging signs include hind leg degeneration, weight changes, and increased susceptibility to illness. Despite this, they remain loving, expressive companions.
Key traits:
May develop thin fur, wobbly gait, or vision decline
Spend more time resting or snuggling
Decreased play drive but stronger emotional bonds
Watch Me Grow!
Ever wonder just how much a baby rat changes in just a few short weeks? Below is a visual timeline following the growth of two of our pups from birth to almost 5 weeks old.
