Your puppy's behavioural development
The main stages of development
- The very beginning (0 to 2 weeks): he is born blind and deaf, and does nothing but nurse and sleep against his mother.
- Waking up (2 to 3 weeks): his eyes and ears open, he takes his first steps and his first teeth come through.
- The socialisation window (roughly 3 to 12 weeks): the big moment, when everything he discovers calmly becomes normal for life. He arrives with you in the middle of it, around 8 weeks. It doesn't close sharply: it then tapers off on a gentle slope, often until around three and a half or four months depending on the dog, so it spills over a little into the next stage.
- The little explorer (3 to 6 months): he grows in confidence and starts testing the limits.
- The adolescent (6 to 18 months): the teenage phase, he tests everything and the recall can slip backwards.
- The young adult (from around 18 months): his emotions settle.
Every puppy moves at his own pace: these age markers are trends, not a calendar to tick off.
Step 1 / 5A puppy who arrives with healthy social foundations.
- With his mother and his littermates, he is already learning to soften his bite and to settle himself.
- If you are still choosing your breeder, look at how the puppies live: a calm mother and pups already handled gently start with a head start.
- French law forbids handing over a puppy before 8 weeks: this time with his mother is not negotiable.
- Your puppy is already home? This stage is behind you, and the rest starts now.
Link the world to positive feelings, while curiosity still wins out over fear.
- Take him out from his very first day at home: don't wait for the last vaccine booster to show him the world.
- Let him discover varied sounds, surfaces, people and dogs, always at his own pace, never by forcing him.
- Start small: two or three people, a few noises, then build up gradually.
- Past three months, the window doesn't slam shut: it stays useful on a gentle slope, often until around three and a half or four months depending on the dog. Simply carry on: the longer you wait, the more patience it takes.
Move on when: He meets novelty with curiosity rather than worry.
A clear, predictable framework where he knows what is expected of him.
- He grows in confidence and tests the limits: that's normal, guide him through it without making a drama of it.
- Set up a gentle routine (meals, walks, play, quiet time) that gives him his bearings.
- Slip in very short training moments, a few minutes, through play.
Get through the teenage phase without damaging the relationship.
- The recall can slip backwards: put the long line back on, that long lead which lets him explore without letting him go, and take the twenty metre one to rebuild the recall, calmly, without losing your temper.
- Increase both physical AND mental exercise: this is the moment it needs to go up.
- Keep exactly the same rules as before, no harsher and no softer.
Move on when: He comes back on recall and calms himself down on his own.
A settled companion, who goes on learning all his life.
- His emotions settle: the adolescent rollercoaster quietens down.
- Keep taking him out, keep making him think and keep varying his encounters: it never really stops.
“Below his comfort threshold” means: as long as he stays curious and relaxed, not overwhelmed. Learn to read the signs that it's too much for him: he backs away, freezes, pants when he isn't hot, turns down a treat he usually loves, keeps his tail low or tucked under his belly. As soon as you see them, move him a little further from whatever is impressing him and let him breathe: that's how a discovery stays a positive one.
The socialisation window
Between 3 and 12 weeks, so up to around three months old, your puppy is a genuine sponge: he takes in novelty almost without fear, and whatever he meets calmly at that point becomes “normal” for the rest of his life.
That is what a landmark study of hundreds of puppies showed back in 1965, and what the position of American veterinary behaviourists has confirmed since, in 2008: it is the period when his urge to go and look still wins out over his fear. As he arrives with you around 8 weeks, you catch the second half of it: don't waste those weeks.
After that, nothing slams shut. His fear of novelty rises little by little and eventually takes over, but the window stays useful on a gentle slope, often until around three and a half or four months depending on the dog.
And if you take in an older dog, or one kept too far from the world early on, positive experiences later on make up part of the lost ground: a 2022 scientific review finds as much, while staying cautious about what it gives in the long run. A puppy who arrives late is never a lost cause, it will simply take more patience and more method.
Some dog trainers also talk about two periods when a puppy is a little more easily frightened by something new: one around 2 to 3 months, another during adolescence. Nobody has pinned down precise dates that would hold for every dog: this marker is there to keep you attentive, not to tick off a calendar. What you can do at those ages: don't impose any big novelty on him (a house move, fireworks, a large crowd), keep him below his comfort threshold and never push him towards what frightens him. Don't cancel everything either, carry on with your usual outings: a bad experience simply leaves a slightly deeper mark at those ages than at another moment.
Your day-to-day markers
Nothing extraordinary: it is these small habits, repeated, that build a settled dog.
0 / 6Every puppy is different
Ten puppies raised the same way will give ten different personalities, and that's just as well. A shy puppy is not a failed puppy: shyness is a character trait, not an illness. And breed doesn't decide everything: a large 2022 genetic study of more than 18,000 dogs shows that it explains only around 9% of the behavioural differences between two dogs. Your job is to guide the dog in front of you, not the cliché of his breed. Small breeds often mature earlier, giant ones later: respect your dog's pace.
What you handle yourself, what needs a professional
What you handle yourself
- Showing him the world, below his comfort threshold.
- Setting up a routine, playing, teaching him short tricks with the marker word.
- Redirecting the nibbling onto a toy and praising his good choices.
What needs a professional
- Repeated growling at visitors, even from a small puppy “who makes everyone laugh”.
- A panicked fear that doesn't pass, or an aggression that is settling in.
- Marked guarding of the food bowl, the toys or the bed.
You are not failing by calling a trainer or a behaviourist: you are giving your dog access to someone trained for this particular problem.
- Scott & Fuller — Genetics and the Social Behavior of the Dog (1965)
- AVSAB — Position Statement on Puppy Socialization (2008)
- AVSAB — Humane Dog Training Position Statement (2021)
- McEvoy et al. — Review of puppy socialisation and behavioural development (2022)
- Morrill et al. — Ancestry-inclusive dog genomics (Science) (2022)
Keep going
Frequently asked questions
At what age can you teach a dog tricks?
From the moment he arrives, around 2 months old: a puppy loves learning tricks. The secret is very short sessions (1 to 2 minutes), several times a day, in the form of a game. You guide the movement with a treat, you mark the moment with a “yes!” and you reward him. A trick should stay fun, never a chore.
At what age can you take a dog to training classes?
At home, learning starts from 2 months old. For a puppy class or a dog club, you can sign up from 7 to 8 weeks: all you need is a first vaccine injection given at least a week beforehand, a first worming treatment, and a venue that only takes healthy, properly looked after dogs. No need to wait for the end of all the boosters. But bear in mind that the club is a supplement: the bulk of socialisation happens outside, in real life, not in a hall for an hour a week.
Why does my puppy bark at other dogs?
Most of the time it is excitement or a little fear, not aggression. The lead often has a lot to do with it: held short, his only choice is to put up with it or to charge in. Switch to a slack long line, keep your distance so that he stays calm, and reward the moment he looks away. Never punish him: that would only reinforce his fear.
At what age should you start training a puppy?
It starts as soon as he arrives, but not with a list of bans. For the very first days, mostly let him discover his home and settle in. Once he seems at ease, generally after a few days, you introduce the first markers one by one: his name, “sit”, the routine of meals and walks. A predictable framework reassures him far more than a string of “no”.
Up to what age can you socialise a puppy?
The bulk of it happens early: between roughly 3 and 12 weeks, everything he discovers calmly becomes normal for life. As your puppy arrives with you around 8 weeks, you catch the second half of it: that's when to go for it, don't waste those weeks. After that, it doesn't stop dead: the window closes on a gentle slope, and in many puppies it stays useful until around three and a half or four months. The longer you wait, the more patience it takes, but a dog adopted older is never a lost cause.
My puppy nibbles a lot, is that normal?
Yes, completely: his teeth are coming through and he discovers the world with his mouth. It is a stage of his development, not a deep problem. When he grips too hard during play, mark it with a sharp “ouch!” and stop for a few seconds, then offer him a chew toy. Never any physical punishment.
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