PuppyweeksPuppy development
Young Adult: what to expect
The first birthday is a handover, not a finish line — dogs are physically mature or close, but emotional maturity keeps developing, often into the second year. Expect a calmer, more predictable dog with occasional adolescent flashbacks. Training now is about maintaining and proofing what you built, not starting over.
When does this happen?
| Toy · Small | Weeks 53–104 |
|---|---|
| Medium | Weeks 66–104 |
| Large | Weeks 79–104 |
Bigger dogs stay adolescent longer — larger breeds reach each later stage weeks after smaller ones.
Not sure this is your puppy’s exact stage? Check the Puppy Stage Finder. Wondering what’s still normal to expect as an adult dog? Get a straight answer.
Common questions
Is my dog fully grown at one year?
Most small and medium dogs are physically mature or close by their first birthday; large and giant breeds finish later. Either way, social and emotional maturity keeps developing into the second year — adolescence tapers off gradually rather than switching off.
When should I switch my dog to adult food?
As growth slows, on your vet’s timeline — smaller dogs transition earlier than large breeds. Confirm the switch to an adult-maintenance diet with your vet, and keep an eye on weight as activity and metabolism settle.
Grounded in established canine behavioural science — see our sources.