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A puppy's first year is not one long stage but nine distinct ones, each with its own feeding pattern, its own socialization jobs and its own vet milestones. This hub is the index to our development series: one page per stage, written to be read at the age you are actually living through. If you want the whole year on a single page first, start with our puppy development week by week guide, then come back here for the stage you are in.
Read the stage you are in, plus the one before it if you have just arrived. Every stage page follows the same shape: what the puppy is like, feeding transitions, the socialization and training jobs that belong to those weeks, and the vet milestones, which follow the AKC vaccination guideline and the MSD Veterinary Manual owner guidance throughout. Stages link forward and back, and every page links to the first year hub, where the printable checklist, the first vet visit checklist and the cost timeline live.
Two cautions apply to the whole series. First, timings are typical ranges, not deadlines: a puppy a week behind a chart is usually just a puppy. Second, anything that looks like illness, pain, failure to gain weight or a sudden behavior change is a veterinary question, not a development stage, and should be treated as one promptly.
The first year divides into the newborn stage (weeks 1 to 2), the senses and weaning stage (weeks 3 to 4), the curiosity stage (weeks 5 to 6), homecoming (weeks 7 to 8), the socialization sprint (2 to 3 months), teething and boundary testing (3 to 4 months), the juvenile stage (4 to 6 months), adolescence (6 to 9 months) and the young adult stage (9 to 12 months). Each stage in this series has its own page.
The week by week guide covers the whole year on one page for a fast overview. This series gives each stage its own page, with more room for feeding transitions, socialization jobs and vet milestones at exactly the age you are living through.
Proportionally, the first weeks: newborns roughly double birth weight in the first week or so, and growth stays rapid through the first 4 to 6 months before slowing. Small breeds finish growing around 6 to 8 months; large and giant breeds grow for 12 to 24 months.
The weeks from about 3 weeks to 3 or 4 months, with the 2 to 3 month page covering the heart of the window after homecoming. Experiences in this stretch are filed as normal more easily than at any later age.
The sequence is the same for every breed, but the timing shifts: small breeds run ahead, often reaching each stage early, while large and giant breeds develop more slowly and stay in the growth stages far longer. Use the stages as a map and your veterinarian's growth checks as the compass.
This page is general information drawn from the published guidance of the organizations listed under Sources below. It is not veterinary advice, and it does not replace your own veterinarian, who knows your dog. If your dog has eaten something toxic, contact your veterinarian, the ASPCA Animal Poison Control Center on (888) 426-4435, or the Pet Poison Helpline on (855) 764-7661 straight away. A consultation fee may apply on the helplines.
Last updated: November 2026. How we work: our methodology.