The Key Stages in a Dog’s Early Development

Canine ontogeny, or the development of dogs from conception to adulthood, is a complex and intriguing process. It is characterized by a series of six “natural” stages: (1) the prenatal period; (2) the neonatal period; (3) the transition period; (4) the socialization period; (5) the juvenile period; and (6) the pubertal period. Understanding these stages is crucial in guiding strategies for training, socialization, and overall care for puppies, ensuring they grow into well-adjusted adult dogs. In this entry, I’m going to briefly describe each of these stages (aka “critical” or “sensitive” periods). At the end of the entry, I will provide you with recommendations for further reading.

1. Prenatal Period

The journey begins with the prenatal period, which stretches from conception to birth. During this time, the developing puppy relies entirely on its mother for nutrition and protection. The mother’s health and well-being can significantly impact the puppy’s development. Nutritional deficiencies, stress, or exposure to harmful substances during this time can have long-lasting implications for the puppy’s health and behavior.

2. Neonatal Period

Immediately following birth, puppies enter the neonatal period, which lasts until about two weeks of age. This period is characterized by limited sensory and motor capabilities. Newborn puppies are both deaf and blind, spending most of their time sleeping and nursing. Despite their limited interaction with the world, early tactile experiences and their mother’s care are still vital for their development during this stage.

3. Transition Period

The transition period is a short but significant stage, beginning around day 13 (plus or minus 3 days) and lasting until about day 18-20. During this phase, puppies undergo rapid sensory development. Their eyes and ears, closed at birth, begin to open, introducing them to the world of sights and sounds for the first time. This marks the beginning of a crucial period of sensory learning and development.

4. Socialization Period

From about four weeks to twelve weeks of age, puppies enter the socialization period. This stage is arguably the most critical period in a dog’s life when it comes to behavioral development. During this time, puppies become more aware of their surroundings and start to interact with other dogs and humans. They are highly receptive to learning about their environment, and positive experiences during this window can have a profound impact on their future behavior. Conversely, lack of exposure or negative experiences during this stage can lead to behavior problems later in life.

5. Juvenile Period

Following the socialization period is the juvenile period, which lasts until the onset of puberty (varying by breed and individual dog). Dogs start exploring their environment more during this stage, and their personalities continue to develop. Continued training and socialization are essential during this period to reinforce good behavior and prevent the development of unwanted behaviors.

6. Pubertal Period

The final stage of early development is the pubertal period, marking the onset of sexual maturity. This usually occurs between six months to a year, depending on the breed. Dogs will begin to exhibit adult sexual behaviors during this time, and females will experience their first heat cycle.


Understanding canine ontogeny is essential for dog owners, breeders, and trainers. It allows them to provide the necessary care, socialization, and training that’s appropriate to each stage of development, promoting the growth of healthy, well-adjusted dogs. Moreover, this knowledge contributes to our understanding of the profound and lasting effects of early life experiences on an individual’s development and behavior.

Further Reading

  1. Scott, John Paul, and John L. Fuller. 1965. Genetics and the Social Behavior of the Dog. Chicago: University of Chicago Press.
  2. Coppinger, Raymond, and Mark Feinstein. 2015. How Dogs Work. Chicago: University of Chicago Press.
  3. Miklósi, Adám. 2015. Dog Behaviour, Evolution, and Cognition. Second Edition. Oxford: Oxford University Press.
  4. Serpell, James. 1995. The Domestic Dog: Its Evolution, Behavior and Interactions with People. Cambridge: Cambridge University Press.
Print This Post Print This Post
Tony Bierman, "The Key Stages in a Dog’s Early Development," OBTESA, Accessed June 6, 2023,