Puppies change faster in their first four months than at any other point in their lives. Eyes open around 10 days, hearing arrives at about 2 weeks, all 28 baby teeth are through by 6 weeks, and the window that shapes adult behaviour closes at around 12 weeks. Enter a birth date to get the whole timeline with real dates.
Not sure? A vet can estimate age from teeth fairly accurately.
Typical ranges for healthy puppies. Individuals vary, and large breeds run behind small ones on the later milestones.
When do puppies open their eyes?
Around 10 days old, though anywhere from roughly 10 to 14 days is ordinary, and some puppies take a little longer. They open gradually, often one eye before the other, and what is behind them is not finished vision: it is blurry, grey, and light-sensitive for another couple of weeks.
Week by week: what happens when
| Age | What changes |
|---|---|
| Birth to 1 week | Blind, deaf, and unable to control body temperature. Normal temperature is only 95 to 99°F. Should gain 5 to 10% of body weight daily |
| About 10 days | Eyes open |
| 2 weeks | Ear canals open and hearing begins. Baby teeth start pushing through |
| 3 to 4 weeks | Walking becomes steady, and they finally regulate their own temperature |
| 4 to 6 weeks | Weaning onto soft food. All 28 baby teeth usually through |
| 8 weeks | Earliest sensible age to go to a new home |
| 8 to 12 weeks | The socialisation window, the most behaviour-defining period of a dog’s life |
| 12 to 16 weeks | Baby teeth fall out, adult teeth arrive, chewing peaks. Ready for training classes |
| About 6 months | All 42 adult teeth usually in place |
| 6 to 12 months | Adolescence, and the stage where training appears to unravel |
| 12 to 18 months | Emotional maturity, later in large breeds |
Puppy teeth: 28 in, 42 out
Puppies grow 28 deciduous teeth, usually all through by 5 or 6 weeks. From 12 to 16 weeks they start falling out, replaced by 42 adult teeth that are normally all in place by about 6 months. Most owners never find the baby teeth, because puppies swallow them while eating.
Two things worth knowing:
- Chewing peaks during teething, and it is not naughtiness. Give appropriate chews and keep valuables out of reach for a couple of months.
- Retained baby teeth need a vet. If a baby tooth is still in place once the adult tooth has come through, especially a canine, it crowds the mouth and traps food. They usually need removing, often while the dog is under anaesthetic for neutering.
The socialisation window is the part that matters most
Of everything on this page, the weeks from 8 to 12 have the largest permanent effect. What a puppy meets calmly in that window tends to stay unremarkable for life; what they never meet can become frightening later.
This collides with the vaccination schedule, and the collision is genuine. The practical answer most behaviourists give is not to choose one over the other: carry your puppy in high-risk places, invite vaccinated adult dogs to your home, let them meet people of all kinds indoors, and walk them on surfaces, in the car, past traffic, through noise. Our puppy vaccination schedule shows where your puppy is in the course, and our guide on how to socialise a puppy covers the safe ways to do it before the final shot.
Frequently asked questions
When do puppies open their eyes?
When can puppies hear?
How many teeth do dogs have?
When do puppies stop teething?
When is a puppy fully grown?
Where these numbers come from
- Milestones: the American Kennel Club’s A Puppy Growth Timeline (eyes around 10 days, hearing from about 2 weeks, walking by 4 weeks, home at 8 weeks, socialisation through the first three months, permanent teeth from 12 to 16 weeks, emotional maturity at 12 to 18 months).
- Teething: the AKC’s Puppy Teething Timeline (28 baby teeth, shedding from weeks 12 to 16, 42 adult teeth by about 6 months, retained teeth need veterinary attention).
- Newborn figures: the Merck Veterinary Manual on neonatal care (no thermoregulation until 4 weeks, normal temperature 95 to 99°F in week one rising to 99 to 101°F by week four, normal weight gain of 5 to 10% of body weight per day).