about: the domestic dog Expand: date=February 2009

A puppy is a juvenile dog, generally less than one year of age. Puppy size varies among breeds: smaller puppies may weigh , while others are . All healthy puppies grow quickly after birth. A puppy's coat color may change as the puppy grows older, as is commonly seen in breeds such as the Yorkshire Terrier. In vernacular English, puppy refers specifically to dogs while pup may be used for other mammals such as seals or even rats.

Development

Born after approximately 61 days of gestation, puppies emerge in an amnion which is bitten off and eaten by the mother dog. Puppies begin to nurse almost immediately. If the litter exceeds six puppies, particularly if one or more are obvious runts, human intervention in hand-feeding the stronger puppies is necessary to ensure that the runts get proper nourishment and attention from the mother. As they reach one month of age, puppies are gradually weaned and begin to eat solid food. The mother may regurgitate partially digested food for the puppies or might let them eat some of her solid food. By the age of about seven weeks, puppies no longer depend on nursing for food. Although they may continue trying to nurse, the mother dog usually refuses after this age, though she might let them occasionally nurse for comfort.

At first, puppies spend ninety percent of their time sleeping and the rest feeding. During their first two weeks, a puppy's senses all develop rapidly. Puppies open their eyes about nine to eleven days following birth. At first, the retina is poorly developed and their vision is poor. Puppies are not able to see as well as adult dogs . In addition, puppies' ears remain sealed until about thirteen to seventeen days after birth, after which they respond more actively to sounds. While between two to four weeks old, puppies usually begin to growl, bite, wag their tails, and bark.

Puppies develop very quickly during their first three months, particularly after their eyes and ears open and they are no longer completely dependent on their mother. Their coordination and strength improve, they spar with their litter-mates, and begin to explore the world outside the nest. They play wrestling, chase, dominance, and tug-of-war games.

Puppies are highly social animals and spend most of their waking hours interacting with either their mother or littermates. Most people who are thought to be expertsWho: date=March 2009 now believe that being with its mother and littermates until at least eight weeks old is important for a puppy's behavioral development. Responsible breeders will not sell a puppy that is younger than eight to twelve weeks old, and in many jurisdictions, it is illegal to give away puppies younger than a certain age (usually between eight and twelve weeks).