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The neonatal stage: Birth to two weeks
The senses of touch and taste are immediately present after birth.
The mother has the most influence over the puppy. [https://www.thespruce.com/puppy-development-part-1-2804676t] -
The transitional stage: Two to four weeks
Mother and littermates continue to influence a puppy’s behavior.
The sense of hearing and smell develop, eyes open and the teeth begin to appear.
A puppy begins to stand, walk a little, wag its tail, and bark.
A puppy’s eyesight is well-developed by the fourth or fifth week.
[http://dogtime.com/puppies/1130-puppy-behavior-basics-hsus#/slide/1t] -
The socialization stage: Three to twelve weeks
A puppy needs occasions to meet other pets and people during this stage.
By three to five weeks, play becomes important as a puppy becomes aware of his or her surroundings, companions (both people and dogs), and relationships.
the people becomes more influential. With littermates, the puppy learns to play, develops social skills, learns the inhibited bite, explores
[http://dogtime.com/puppies/1130-puppy-behavior-basics-hsus#/slide/1] -
The ranking stage: Three to six months
Ranking (dominance and submission) within the household or “pack,” including people, is seen and used by a puppy in this stage.
Teething and chewing begins.
A puppy experiences another fear stage at four months of age, so be prepared with positive reinforcement and introductions to objects and situations
[http://dogtime.com/puppies/1130-puppy-behavior-basics-hsus#/slide/1] -
The adolescence stage: Six to eighteen months
A puppy is most affected by human and dog “pack” members.
A puppy may challenge people as part of exploring his or her dominance in the “pack.”
At seven to nine months, a puppy will begin exploring more of his or her territory, prompting a second chewing phase.
A puppy will experience the beginnings of sexual behavior if not spayed or neutered.
[http://dogtime.com/puppies/1130-puppy-behavior-basics-hsus#/slide/1]
