Puppies develop from helpless infants to lively puppies in stages,
and different puppies develop at different rates. They also show
personality differences. One puppy may be shy, another nervous
around strange humans, a third might be adventurous.
Puppies should be handled and around humans so they will learn to
accept people as members of the family pack. Between the age of 3
and 4 weeks, puppies can wag their tails. They will wag them when
greeting other dogs in the family as well as the humans. As the
puppies get more socialized, they will extend their greeting to
the people who pick them up to include licking faces.
At four weeks a puppy's play gets rougher, with more attempts to
dominate its fellow puppies and more trials of strength. Within
a pack of puppies, one is the leader, but it is not always the same
puppy. But around this time, the puppies begin to establish position
among themselves. One will emerge as the top dog.
A power struggle between two puppies begins as a friendly game. The
two may be rolling around, mock biting, when suddenly one of them
is on top with the other upside down underneath. The uppermost
puppy becomes rigid, with its legs stiff, tail straight up, and
baring its teeth in a snarl. The lower puppy will push against the
upper one, snarling back. The two puppies continue this for awhile,
then decide something between themselves, and either the uppermost
puppy relaxes, or the lower one gets free.
It isn't necessarily the biggest male puppy that dominates the others.
A lot depends upon the puppy's personality. A small, but feisty, female
can easily dominate a larger, easygoing male puppy.
Source: A Dog's Life: A year in the life of a dog
family, by Jane Burton and Michael Allaby, Howell Book House, Inc.,
New York, 1986, pp. 44-46.