When is a puppy not a puppy?

When does your dog reach maturity? This is a question with no definitive answer. To give an exact age that covers all dogs is impossible as this will very much vary from dog to dog and breed to breed (and you know how some breeds can be unusual). To reach a conclusion, a review of the developmental stages of your puppy’s life from birth to Social maturity need to be considered.

The early dog growth stages are finite periods where exposure to novel experiences, different environments and social interaction play a major part, with the later stages varying in length dependent on breed size and individual dog.

This article is based on scientific research over many years and some of the periods covered are defined in different ways and different time periods, dependent on author.

Dog's developmental stages by age

Prenatal – In utero

Neonatal (Newborn) – Birth to 12 days

Transitional – 12 days to 3 weeks

Socialization – 3 weeks to < 16 weeks

Juvenile – 12 weeks to sexual maturity

Adolescent – Sexual to social maturity (teenage stage)

Adult – Social maturity to 7 years

Senior – 7+ years


During the period in the womb, fetal development is affected by several factors. These are related to the mother’s experiences whilst pregnant. Nutrition of the mother plays a big factor as does her emotional state. Heightened stress and fearful experiences can create emotionally unstable puppies.

Hormones have a part to play too. Testosterone is responsible for masculinizing the male brain at this time. For female puppy, the position in the womb and where they are in relation to male puppies will increase their exposure to testosterone, causing them to take on some male-like tendencies such as leg lifting in adulthood.

Neonatal (Newborn) – birth to 12 days

During this dog maturity period after birth, puppies are blind and deaf with early stimuli coming from temperature, pressure, taste & smell. They are completely reliant on their mothers during this time including stimulating urination and defecation. External influences can affect future behavior and positive stimulation has proven to be effective and an important part their adult emotional reactivity and problem solving.

Transitional – 12 days to 3 weeks

Puppies start to become more active, their eyes (10-14 days) and ears (14-18 days) open and they can start to walk as early as 12 days old. They start to urinate and defecate independently. This is a critical dog maturity period; what they learn from their mother and siblings will stay with them for life. This is the period to begin exposure to novel objects and other stimuli.

Socialization – 3 weeks to around 16 weeks

This dog development stage is split into two, primary socialization 3 – 5 weeks and secondary socialization, 6 – 12 weeks. During the primary period, the puppy is still with its mother and siblings and the breeder can have an influence on future behavior. Exposure to a wide range of noises of varying type and level is important as the puppies have yet to develop fear.

The secondary period that starts when the puppy is still with the breeder should include short periods of separation from their litter mates and should be experiencing a wide range of new challenges such as the outside world, car travel, activity courses, different surfaces, water etc. Weaning starts around 5 – 7 weeks.

At 8 weeks old the puppies start to move to their new homes where continued, positive exposure to novel stimuli is crucial for the future prevention of fearfulness and anxiety that can continue to adulthood. Vaccinations are usually carried out from 7 or 8 weeks. Interacting with other puppies and sensible adult dogs plays a part in the socialization process where learning appropriate play moves from their siblings to other dogs. Puppy classes can commence to aid this process.

The end of this period and dog's mental maturity will vary from puppy to puppy.

Juvenile – Around 16 weeks to sexual maturity (6 to 9 months)

Puppies become progressively more independent during this dog’s mental maturity period. Sex hormones start to kick in bringing with them a new level of confidence. Early training can seem to be forgotten so it is important to continue during this time. This is sometimes referred to as the ‘flight period’ when puppies test their wings. This can start at around 5 months for some puppies. This can be a tricky time for puppies to be off lead when early recall progress disappears.

Permanent teeth begin to emerge at around 18 weeks. Exposure to novel stimuli should continue to prevent regression and puppies will start to show more reluctance to approach unfamiliar things.

A bitch will usually have her first season towards the end of this dog’s maturity period and males will start to lift their legs.

Adolescent – Sexual Maturity (6-9 months) to Social Maturity (2-3 years)

Puberty continues and skeletal maturity occurs at 8-12 months (dependent on breed). This is evidenced by the closure of the growth plates.

This is often referred to as the ‘teenage’ stage where the pups are sexually mature but still have a way to go to be socially mature.

When is a Puppy Considered an Adult Dog?

So, to answer the question, ‘how to recognize that puppy is no longer a puppy’?

Based on the evidence above, this should be around 9 months when they reach sexual maturity. However, it is more often considered to be 12 months old when they have reached sexual maturity and their growth plates have closed. For more information on professional animal training, please visit https://tromplo.com/

Author: Martin William

All pictures we got from our Animal's Look Facebook page fans except the last two.


Brice C Ryan et al 2002, Intrauterine Position Effects

Lindsay S R 2000, Handbook of Applied Dog Behaviour and Training Vol 1

Hastings P & Rouse E 2004, Another Piece of the Puzzle: Puppy Development

Scott JP & Fuller JL 1965, Genetics and the Social Behavior of the Dog

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