Puppy Development Timeline: Week-by-Week Guide From Birth to 12 Months

Puppy development is commonly divided into several stages: the neonatal period from birth to about 2 weeks, the transitional period from about 2–4 weeks, the socialization period from roughly 3–12 weeks, the juvenile period from about 3–6 months, and adolescence from around 6–12 months. The exact timing varies between individual puppies and breeds.

Most puppies begin opening their eyes at around 10–14 days of age. Their vision is still developing at first, so they do not see as clearly as an adult dog. If a puppy’s eyes have not opened by around two weeks, or there is swelling or discharge, contact a veterinarian.

Puppies usually begin trying to stand and walk during the third week of life. Their movements are initially unsteady, but coordination improves quickly as their muscles, balance, and nervous system develop.

Puppies generally begin transitioning from their mother’s milk to solid food at around 3–4 weeks of age. The transition is gradual, with puppies becoming increasingly dependent on puppy food as they approach weaning.

Puppy teeth usually begin appearing at around 3–4 weeks of age. By approximately 6–8 weeks, most puppies have their full set of deciduous teeth. Adult teeth then begin replacing the baby teeth at around 3–4 months.

The early socialization period is especially important during the first few months of life, with many veterinary and behavior sources emphasizing the period from approximately 3–12 weeks. Puppies should be introduced gradually and positively to people, sounds, handling, environments, and appropriate dogs while avoiding overwhelming experiences.

Many puppies go to their new homes at around 8 weeks of age, although the appropriate timing can vary depending on the puppy, breeder, litter, and local regulations. Puppies benefit from continued interaction with their mother and littermates during early development, including learning appropriate social behavior.

Puppy vaccinations commonly begin at around 6–8 weeks of age, followed by additional doses according to the vaccine used, the puppy’s risk factors and your veterinarian’s schedule. Because maternal antibodies can affect vaccine response, puppies usually need a series of vaccinations rather than a single dose.

Dogs generally enter adolescence at around 6 months of age, although the timing varies considerably by breed and individual. During adolescence, puppies may become more independent, energetic or easily distracted. Large breeds can mature physically and behaviorally later than smaller breeds.

There is no single age when every puppy becomes fully grown. Small breeds may reach adult size earlier, while large and giant breeds can continue growing for considerably longer. Even after reaching their adult height, some dogs continue developing muscle and body condition.

No. Puppy development varies according to breed, genetics, nutrition, health, and individual differences. The ages in a puppy development timeline should therefore be treated as general milestones rather than exact deadlines. If a puppy appears significantly behind expected developmental milestones or suddenly stops progressing, speak with a veterinarian.

A missed milestone does not necessarily mean something is wrong, because puppies develop at different rates. However, significant delays, regression, weakness, difficulty walking, problems seeing or hearing, poor feeding, persistent vomiting or diarrhea, or other concerning symptoms should be discussed with a veterinarian.

Puppies change rapidly during their first year. Newborn puppies mainly sleep, feed, and depend on their mother. Around 2–4 weeks, their eyes and ears open and they begin walking and exploring. From about 4–12 weeks, socialization, play, learning, and coordination develop rapidly. From 3–6 months, puppies become more independent and begin losing their baby teeth. From about 6–12 months, adolescence brings further physical, social, and behavioral changes.

Puppy growth varies greatly by breed, adult size, genetics and individual health, so there is no single amount of weight a puppy should gain each week. Small breeds generally mature faster than large and giant breeds, while larger puppies may continue growing for much longer. Your veterinarian can help you track your puppy’s weight and body condition using an appropriate growth chart.