Dogs are altricial, meaning they are born unable to hear, see, smell or regulate their own body temperatures. On average they have a gestation period of 59 to 63 days, meaning they are born approximately two months after being conceived.
The Neonatal Developmental Period, from birth to twelve days of age, is also called the reflexive behavior period. During this early developmental stage, puppies are responsive to external stimuli. The dam will encourage the pups to nurse, will stimulate them to eliminate bodily wastes, will clean them and provide general care and protection necessary for their survival.
During the Transitional Developmental Period, from two weeks to three weeks, the puppies first open their eyes, can hear and when they begin to become semi-ambulatory (mobile). Toys can be introduced at this stage and humans can begin handle the puppies at this stage.
During the Primary Developmental Period, from three to five weeks, the puppies begin to become more self-aware. Sensory abilities like sight and hearing become mastered and the puppies actually begin walking. During this stage the puppies should be handled several times a day and the breeder should provide various substrates for the litter mates to explore in the whelping box. Whelping refers to the birthing of dogs and other carnivorous mammals (i.e. carnivorans).
The Primary Canine Socialization Period, from two weeks to 16 weeks (4 mos.), is a critical time for litter mates to get to know each other and their human handlers. They learn to bark and chase, and be dogs. They learn corrections from their mothers. During this period they learn things like bite inhibition and that food is a positive environmental stimulus, They learn to defecate in one area of the whelping box and to play in another. This is also the period in which mom begins weaning her litter because their teeth and nails become injurious.
The Secondary Canine Socialization Period, from six to eight weeks represents a developmental stage when the puppies become sensitive to positive and negative external stimuli. Puppies that remain with their litter mates until 8 weeks (2 mos.) have shown to be more well-adjusted and less likely to become fearful biters as mature dogs. Although the fear imprint begins at 8 weeks, by 7 weeks the puppy is first susceptible to fear. Puppies should be permitted to experience fear, but trainers/handlers and owners should refrain from using compulsive training methods, as this is a critical period that can instill lifelong phobias in dogs. Compulsive training aids such as choke-chains, noise makers, squirt bottles, electric stimulus collars or yelling should not be permitted at this stage.
The Optimum Bonding Period begins at seven weeks. Wild canids do not interact with members of their pack other than litter mates until seven weeks of age. Hence, at seven weeks puppies begin to interact and bond with others, including human caretakers. It is between eight and ten weeks that puppies are ready for their permanent homes. At this stage owners should begin to establish boundaries and lay the foundation for proper socialization. This means that the puppies should be allowed to explore their environment without being forced in to stressful or overwhelming situations. Interactions with people should be positive and gentle.
The General Socialization Period, from seven to 16 weeks, is a period when the owner should expose the puppy to as many safe and novel situations as possible. If the puppies are to be introduced to other dogs, regard for the health and vaccination history of the other dogs should be considered.
This synopsis was adapted from literature published by the Animal Behavior College.