"Genetics and the Social Behavior of Dogs" published in 1965 by Dr John Scott and Dr John Fuller is still regarded as one of, if not the most, important and comprehensive studies on the development and behaviour of the domestic dog. It is available to order on Amazon.

Below is a very brief outline of the stages they identify as being crucial in the development and socialisation of puppies and young dogs.


A dog has ten clear stages of psychological development which affect how it interacts with people and other animals and controls its behaviour in situations dependant on its age.  Puppies develop through clearly recognizable stages, each one being characterized by certain behaviour patterns and emotional reactions.  These have been called The Ten Stages and are discussed in further detail below.

1.                  Pre-Natal Period

Environmental factors that affect the pregnant bitch also affect the subsequent development of the puppies mind.  This is why it is critical to give the bitch good all round care.

 2.                  Neo-Natal Period (0-2 weeks)

During this period the dog spends around 90% of its time asleep.  The hearing, vision and temperature regulation are under developed and the pup’s brain is barely myelinated.  The way in which a dam behaves with her offspring will greatly influence its behaviour in later life.

 3.                  Transitional Period (2-4 weeks)

During this period, the sensory abilities come on line, the eyelids open and the first set of teeth appear, the dog will wag his tail and bark for the first time, at this time the litter mates play a much more important role.

By four weeks of age, hearing, pain, touch and vision responses are similar to that of an adult, the brain is almost fully myelinated and the dog is ready for complex learning.

 4.      Socialization Period (To Dogs – 4-6 weeks / To Dogs Humans 4-12 weeks)

From 3 ½ weeks the pups begin to interact playfully.  From this age the pup learns through play, how much pain they can inflict on each other as a result of chewing and biting.

The facial expressiveness of the puppy at five weeks contrasts to the mask like appearance of the puppy at three weeks.  This is due to the development of expressive ear movements, elongation of the muzzle and the improved functions of the muscles that control the lips.

At 4-5 weeks of age, puppies frequently carry small objects in their mouths and engage in tugs of war.  A defensive protective pattern emerges, in which the pup vigorously guards an object or food.  Several puppies may follow one litter mate who is carrying something in its mouth.  These are the first signs of co-ordinated group activity, or pack performance and dominant and submissive behaviour.

This is the optimum time for the dog to establish social relations with other dogs, humans and other species.

Scott and Fuller describe this period as a special time in life when a small amount of experience will produce a great effect on later behaviour.

 5.                  First Fear Impact Period (8-11 weeks)

Any traumatic experience, whether it be frightening or painful will have a more lasting impact on the puppy now, than if it had occurred at any other time in its life.

 6.                  Juvenile Period (12 weeks to maturity)

Most of what occurs in this period will be determined by what went on before.  The dog will experience gradual improvement of the motor skills as he grows in strength and activity.  Consistency is the key during this period, ensuring the dog knows its boundaries is key to guaranteeing that you don’t have unwelcome behaviour.  If the dog hasn’t developed normally through the previous stages, then socialization must take place during this stage.

 7.                  Seniority Classification Period (4-8 months)

This is often referred to as the ‘Age Of Cutting Teeth’.  This period is defined by the dogs test for leadership, very similar to teenage children; the dog will test all members of his pack for weaknesses and then, if allowed, exert his authority and move higher within the pack position.

 8.                  Flight Instinct Period (4-8 months)

Turning a deaf ear is classic behaviour in this period; the dog will often disobey commands, run away, or turn a deaf ear.  It can last a few days or weeks and is again, a test of the owner’s position in the pack.

 9.                  Second Fear Impact (6-14 months)

This is a stage that most people do not understand.  It could occur once, or several times, depending on the dog.  It is marked by a sudden change in behaviour of the now adolescent dog who may suddenly be reluctant to approach something new, or be frightened of something, or someone familiar.  The way in which an owner reacts in this stage is crucial to the dog’s normal development.

 10.             Maturity (1-3 years)

Maturity is a very vague stage, as some breeds do not mature until they are 3-4 years, however, whenever the maturity is reached, it is usually marked by a renewed test for leadership of the pack, especially in male dogs and again, the way in which the owner responds to this is critical.

The way in which breeders, handlers and owners respond to a dogs behaviour is crucial at all the above stages of development, one mistake and the dogs development could quite easily be set back.  This would then need further work and training to ensure the dog grows into a well adjusted, social animal, comfortable in all surroundings.