Puppy Development

Reprinted with Permission by Best Friends Animal Society

Here is a quick summary of the stages of puppy development, starting at birth:

Neonatal: Birth to Two Weeks: From birth to two weeks, puppies are completely dependent on mom for food and care, such as keeping themselves clean. The senses of touch and taste are present at birth.
Transitional: Two to Four Weeks: From two to four weeks, puppies become aware of and interact with their littermates as well as their mother. Their eyes open and their sight is well developed by five weeks. The senses of hearing and smell are developing; their baby teeth start emerging. During this stage, puppies begin to walk, bark and wag their tails.
Weaning from the mother also begins during this phase. At around three weeks, puppies should be started on solid food. Offer the puppies small amounts of soft food in a shallow dish. By the time the puppies are eight weeks old, they should be eating solid food and no longer nursing.
Socialization: Four to Twelve Weeks: From four to six weeks, puppies continue to be influenced by their mother and littermates. They learn to play, gaining needed social skills from littermates, such as inhibited biting (biting to play, not to hurt). The puppies also learn the ins and outs of group structure and ranking within the group.
At this point, if mom is aggressive or fearful of people, the puppies may be affected by her attitude. To socialize your puppies with humans, have a variety of people interacting with them – young (with supervision) and old, male and female.
House-training can begin as early as five weeks, when puppies will follow their mother through a dog door or can be taken out for elimination lessons. At approximately six weeks, puppies can begin in-home training. You should handle all parts of the puppy, 
introduce his first collar and lead, encourage him to come using his name, and reward him with praise and treats. At this age, you can also start training puppies with positive reinforcement methods: using a clicker, praise, and rewards.
At about eight weeks, puppies start experiencing fear; everyday objects and experiences can alarm them. This is a perfectly normal reaction – it doesn’t mean that you will have a fearful dog.
You don’t want to socialize your puppies with other dogs and cats until the puppies have been vaccinated, since they may pick up diseases (such as parvo, distemper, and hepatitis) that can be fatal to puppies. The time to worry about is the period after mom’s protection ends, at between 6–8 weeks, and until after the second vaccine takes effect. By twelve weeks, puppies usually have received a couple of vaccine combo shots and can safely interact with other vaccinated puppies and dogs. Ask your veterinarian if she or he knows of any parvo or distemper outbreaks in your area.
Puppies can socialize with other species of animals as well – horses, cats, whatever animals you would like your puppy to be comfortable around. But, use caution and make sure that the other animals are friendly.
Four to Six Months: During this period, puppies grow rapidly and you may notice daily changes. Even though puppies are very energetic, don’t exercise your puppy too much – he can overdo it! Among themselves, puppies begin to use ranking in their group structure – that is, they start testing where they fit in. Puppies may experience another fear phase that lasts about a month and seems to come from nowhere. Again, this is a perfectly normal part of puppy development and is nothing to be alarmed about.
Adolescence: Six to Twelve Months: Like most adolescents, puppies are very rambunctious, so continue the process of training and socializing your dog during this phase. Socialization and training are important if you want your puppy to be comfortable and act acceptably in public places such as dog parks and beaches, or anywhere that she will meet new dogs and new people.
Social Maturity: Between One and Two Years: By this age, your dog will be socially mature and will know what her ranking is in your 
family. Ongoing training will ensure a respectful and fun relationship between your dog and all human family members, which makes having an animal in the family a daily pleasure. 
Article by Sherry Woodard, who is the dog training and care consultant at Best Friends. She develops resources and provides consulting services nationally to help achieve Best Friends’ No More Homeless Pets mission.