Puppy developmental stages: what to expect from birth to adulthood

• Socialisation window: roughly 3 to 12–14 weeks. Make every new experience positive and gentle.
• First fear period: about 8–11 weeks — often just as puppies go home.
• Teething: about 3–6 months. Provide safe chews and expect mouthing.
• Adolescence: about 6–18 months (longer for big breeds). Training dips are normal.

Ages are approximate. Every puppy develops at its own pace, and small breeds generally mature faster than large and giant breeds.

In the first weeks, puppies learn from their mother and littermates — including bite inhibition, which is how hard they can mouth before it hurts. A good breeder or foster carer handles puppies daily and introduces household sounds, surfaces, and gentle visitors.

Most experts recommend puppies stay with the litter until at least 8 weeks. Laws in many places set this as a minimum age for sale.

This is the most important period in your puppy's life for building confidence. During this window, puppies accept new things fairly easily. After it closes, new experiences are more likely to cause fear. Positive experiences now make a calm, confident adult far more likely.

• People of different ages, appearances, and clothing — hats, beards, uniforms, wheelchairs.
• Household sounds: vacuum, washing machine, doorbell, traffic, thunder (use recordings at low volume).
• Different surfaces: grass, gravel, tiles, grates, wobbly cushions.
• Car rides, a visit to the vet just for treats, being carried through busy streets.
• Calm, vaccinated adult dogs known to be good with puppies.
• Handling: paws, ears, mouth, and gentle restraint, always paired with treats.

The first fear period (about 8–11 weeks): Many puppies go through a phase of being easily startled. Something scary during this time can make a lasting impression. Keep new experiences gentle, let your puppy approach at its own pace, and never force it towards something it is scared of.

Puppies grow quickly, become more confident and independent, and start testing what they can get away with. It is a great time to build foundation training: sit, down, recall, leave it, and loose-leash walking.

Teething: Baby teeth fall out and adult teeth come in from about 3 to 6 months, with all adult teeth usually in by around 7 months. Expect more chewing and mouthing. Offer a variety of safe chews, including frozen ones, and redirect mouthing on hands to toys.

House-training: Bladder control improves month by month. A rough guide is that puppies can hold it for about as many hours as their age in months, plus one — so a 3-month-old can usually manage about 4 hours during the day. Overnight is often a little longer.

Adolescence is when many owners wonder what happened to their puppy. Hormones kick in, confidence rises, and the world becomes much more interesting than you. Recall and loose-leash walking often fall apart for a while. This is normal, and it passes.

• Keep training sessions short and frequent, and reward generously.
• Use a long line for recall again if needed.
• Expect a second fear period, when your dog may suddenly be worried by familiar things. Be patient.
• Adolescence is a common time for dogs to be given up to shelters. Knowing it is a phase helps.
• Talk to your vet about the right timing for spay/neuter — recommendations vary by breed and size.

Until growth plates close, avoid repetitive high-impact exercise like long runs, jumping from heights, and hours of ball-chasing. Free play on soft ground and walks of sensible length are fine. Ask your vet when your dog is ready for more strenuous activities.

• When is the puppy socialisation period? The socialisation period runs from about 3 to 12–14 weeks of age. Positive experiences with people, places, sounds, and other dogs during this window have the biggest impact on adult confidence.
• When do puppies go through a fear period? Most puppies have a fear period at about 8–11 weeks, and many have a second one during adolescence, somewhere between 6 and 14 months. Keep experiences gentle and positive during these times.
• When does puppy adolescence start and end? Adolescence usually starts around 6 months and lasts until about 18 months, or up to 2–3 years for large and giant breeds. Training setbacks during this time are normal.
• When do puppies stop teething? Teething usually runs from about 3 to 6 months of age, with all adult teeth in by around 7 months. Some dogs keep chewing heavily for a while after.