Aging and behavioral development
Canine behaviour is a combination of instinct and environment. Dogs are born with certain innate characteristics that are evident from birth. Puppies are born blind and deaf, totally dependent on the dam for warmth and nourishment. The dam will instinctively suckle and protect her young, often keeping other dogs and all but the most trusted people away from the whelping box. Between 10 and 14 days after birth, the eyes and ear canals open, and the puppies begin to move actively around their nest. As they grow, they become more curious and start to investigate their surroundings independently. The dam will begin to leave them alone briefly. During this phase they relate most intensely to their littermates and dam and may become unhappy at being removed from their familiar surroundings. This stage of development lasts about 20 days and is the first of four critical periods.
Beginning at three weeks of age, the most adventurous puppies will seek ways to get out of the whelping box and will start to investigate the larger world. At this age puppies are receptive to human contact, which is essential if they are to bond with people when they become adults. Dogs left alone from four weeks on will never reach their full potential as pets and will often become independent and more difficult to train than those accustomed to close human contact from an early age. At the same time, during the period between three and seven weeks, it is important that puppies socialize with their littermates and dam. This is when the dam weans her puppies, first by regurgitating some of her own food and then by not allowing her puppies to nurse as often as they would like. At about four weeks of age, puppies can be offered solid food in the form of a soft gruel.
Individual socialization of each puppy in a litter can begin at six weeks of age. This is when puppies begin to be more receptive to handling and attention.
The third critical period in a puppy’s development is from 7 to 12 weeks. It has been shown in studies undertaken at various breeding kennels that this is the best age to form human-dog relationships. Attachments formed during this period will affect the attitude of the dog toward humans and toward its acceptance of direction and learning. During this period the pack instinct, which has played such an important role in the puppy’s early development, can be transferred to humans. At this time environment becomes a vital part of the dog’s education and training. This is when a human can most easily establish dominance over the dog, becoming the “leader of the pack.” At this age a dog will accept a submissive role more readily than at any other time in its life. Learning comes most readily at this age. Puppies taught basic commands, even if they are not reinforced for several months, will remember them and respond if they are taught during this critical age.
The fourth critical stage in a puppy’s development is between 12 and 16 weeks. At this age the puppy will declare its independence from its mother and will become increasingly daring in its forays from the familiar. Puppy training can begin during this period, and it is a time of rapid physical and mental growth. The permanent teeth begin to emerge at this time, which is often a painful and distractive process. Puppies need to chew during this period, and, if they are not provided with appropriate teething toys, they will use any available hard object, such as furniture. Puppies at this age may be less willing to cooperate or respond to new commands.
A dog’s personality continues to develop during its entire maturing process and will undergo radical changes while the dog matures sexually and physically. Dogs mature sexually earlier than they do emotionally. Their personalities develop more slowly than their bodies, much like humans but unlike wolves, whose personalities and sexuality develop more harmoniously.
At about seven or eight months many puppies tend to go through a period of anxiety. They are insecure, frightened of strangers, and will appear timid. If this is not an inherited trait, it will disappear within a few months. If it is inherited, that condition will remain and may become accentuated with time.
Concerning how dogs age in comparison with humans, whether seven dog years are really equivalent to one year of human life, see here.