The second week of life brings great changes for the puppy. Ears and eyes sealed since birth begin to open during this period, ears at about two weeks and eyelids between ten to 16 days. This gives the furry babies a new sense of their world. They learn what their mother and other dogs look and sound like, and begin to expand their own vocabulary from grunts and mews to yelps, whines and barks. Puppies generally stand by day 15 and take their first wobbly walk by day 21.
By age three weeks, puppy development advances from the neonatal period to the transitional period. This is a time of rapid physical and sensory development, during which the puppies go from total dependence on Mom to a bit of independence. They begin to play with their littermates, learn about their environment and canine society, and begin sampling food from Mom's bowl. Puppy teeth begin to erupt until all the baby teeth are in by about five to six weeks of age. Puppies can control their need to potty by this age, and begin moving away from sleeping quarters to eliminate.Socialization Period: Week Four-to-Twelve
Following the transitional phase, puppies enter the socialization period at the end of the third week of life; it lasts until about week ten. It is during this socialization period that interaction with others increases, and puppies form attachments they will remember the rest of their life. The most critical period--age six to eight weeks--is when puppies most easily learn to accept others as a part of their family. Refer to the article on how to socialize puppies.
Beginning at four weeks of age, the bitch's milk production begins to slow down just as the puppies' energy needs increase. As the mother dog slowly weans her babies from nursing, they beginsampling solid food in earnest.
The environmental stimulation impacts your puppy's rate of mental development during this time. The puppy brain waves look that of an adult dog by about the 50th day, but he's not yet programmed--that's your job, and the job of his mom and siblings. Weaning typically is complete by week eight.Week Eight-to-Twelve
Puppies often go through a "fear period" during this time. Instead of meeting new or familiar people and objects with curiosity, they react with fearfulness. Anything that frightens them at this age may have a lasting impact so take care that the baby isn't overstimulated with too many changes or challenges at one time. That doesn't mean your pup will grow up to be a scaredy-cat; it's simply a normal part of development where pups learn to be more cautious. Careful socialization during this period helps counter fear reactions.
Puppies may be placed in new homes once they are eating well on their own. However, they will be better adjusted and make better pets by staying and interacting with littermates and the Mom-dog until they are at least eight weeks old--older generally is better. Interacting with siblings and Mom help teach bite inhibition, how to understand and react to normal canine communication, and their place in doggy society. Puppies tend to make transitions from one environment to another more easily at this age, too.
Your puppy still has lots of growing to do. He won't be considered an adult until he goes through several more developmental periods and reaches one to two years of age.