When puppies are born, they are even more helpless than human babies are. However, they progress through stages of development quickly, and most breeds are fully grown by 1 year of age. Human and animal socialization as well as behavioral training are important during the first year of a dog's life.
-
In Utero
-
According to the Pet Education website, puppies in utero can be viewed by X-ray at about 45 days after conception. Their bones begin to form and are visible through radiographs at this age. Gestation lasts around 60 to 70 days. While in the womb, the puppies obtain nutrients through their umbilical cords.
Birth to 2 Weeks
-
Veterinarians often refer to this as the neonatal stage. Puppies are born blind and deaf, but their senses of smell, taste and touch are somewhat developed. This allows them to sense their mother's presence and locate the teats for nursing. Newborn puppies are unable to regulate their own body temperature, so it is important to keep the whelping box warm and not to separate the puppies from their mother. During this time, the mother licks the puppies to stimulate waste elimination, and she consumes it to keep the "den" clean.
2 to 4 Weeks
-
A puppy's ear canal unseals at around 2 weeks, and his eyes open. In addition to sight and hearing, his other senses strengthen during this time. His mobility improves, and his teeth begin to appear. By about 4 weeks, he no longer needs stimulation from his mother to eliminate waste.
4 to 12 Weeks
-
This time period represents the most rapid physical development of a puppy's life. As his body grows, he becomes more curious and playful. He learns socialization and behavior from his mother and littermates. When his play becomes too rough, a yelp from a littermate or nip from his mother teaches him to stop. This helps him learn boundaries.
It is important for puppies to learn human socialization and training during this time. Their senses are strong and their developing brains are impressionable, so the associations they make at this age will affect their behavior as they grow.
By 6 weeks, the owner or breeder can begin the process of weaning the puppies off milk by introducing solid food. By 8 weeks, most puppies are old enough to leave their mother and go to a new home.
3 to 6 Months
-
At this age, a puppy continues to test boundaries and may engage in rough play with his owners and other household pets. The puppy begins teething during this time, and loss of infant teeth is normal. Because of this teething phase, the puppy might chew everything in sight.
Most puppies reach sexual maturation by about 6 months. Male dogs might mark their territory through urination and might engage in dominant behavior. Many veterinarians recommend having your dog neutered or spayed around this time.
6 to 12 Months
-
Female dogs that have not been spayed may go into heat at around 6 to 8 months, attracting male dogs to the area. Some puppies go through an exploratory chewing phase during this time. Most puppies reach their full adult size by 12 months, but some continue to grow until about 18 months.
-