The Critical Periods of
A Puppy's Life

There has been a lot of research done on this subject and although experts may disagree on the exact time that one transitions to another or on exactly what happens in one stage or another, there is general agreement overall. This page will be a consensus of several theories.

First Period: (birth - 3 weeks)

The time from birth to 12 days is sometimes called the Neonatal Period. The newborn puppy is completely dependent on his mother (or on the breeder) to supply warmth and food. He cannot control his body temperature. He needs physical stimulation to urinate and defecate. He cannot see or hear but does respond to the scent of his mother. He crawls forward in a circular pattern, moving his head from side to side as he tries to locate his mother. If he cries, it may stimulate her to nuzzle him so he can find his way to her.

His basic needs are food, sleep, warmth and massage. There is little difference in his brain waves awake or asleep. The pup has reflex response only to hunger, cold, touch and elimination.

There is a Transition Period from day 13-20 when several physical changes occur in the puppy. His eyes open on a average at the 13th day but may open anytime  between the 10th and 19th day. However, he cannot see when they do open. While his pupils will react to light, the retina is still undeveloped and he is unable to see objects or movement until around the 21st. day.  In this period, the puppy will begin to crawl backward as well as forward and a few days later, he will begin to walk on wobbly legs. Once he starts walking, he stops crawling.

Around Day 20 his first teeth begin to come in and he starts to bite and chew. He also begins to wag his tail, but it is not reliant on sight or sound since he still cannot see or hear. He'll  begin startle at a sound around Day 19 or a few days earlier,  but he cannot find the direction or source of the sound.


Second Period: (3 - 4 weeks)

Time between the 21st -28th days is sometimes called the Awareness Period. The puppy begins to see and hear. Because this happens so suddenly, almost overnight, he needs a very stable environment. His basic needs are food, sleep, his mother, canine socialization with his littermates, and some limited socialization with humans. Very gentle handling is necessary as negative events can bring the inborn characteristics of nervousness to light. Negative happenings can create shyness and other undesirable qualities in a puppy. Once developed, these traits will be difficult, if not impossible, to erase. Weaning or moving the litter to a new location is very likely to cause psychological damage to the puppies.

Learning begins during the Awareness Period and the puppy begins to learn what it is to be a dog.

Third Period:  (5-7 Weeks)

The Canine Socialization Period may begin as early as the 21st day and continue through the 49th day. The puppy begins to use the specific behaviors that make him a dog. He begins to experience the beginning stages of the "social pecking order' and to reach his genetic potential, must stay in the nest with his mother and littermates during this time. He begins to practice body postures, facial expressions and vocalizations. He learns how to bark and be barked at, how it feels to bite and be bitten and he learns how his actions have an effect on his mother, littermates and other dogs. Such learning and activity tempers their own biting and vocalizing. From the age of five weeks, the mother teaches her puppies basic manners. They learn to be submissive to her leadership and what behaviors are acceptable. If necessary, she growls, snarls, or snaps at them as a form of discipline. If a pup has not learned to accept leadership and discipline in its early interactions with dogs, its training will be more difficult. Puppies that are removed from the nest too early tend to be nervous, more prone to barking and biting, and less responsive to discipline.

At this stage, the puppies are also beginning to form attachments to humans  and they are now able to recognize people. At seven weeks, each pup will need individual time away from the litter and his mom so he learns that he is an individual. Training must begin in simple terms. He is learning now, whether or not he is being taught. He is also learning bad habits. However, this is the time he is learning to LEARN. Regularity in human socialization is necessary. Puppies will begin to leave their box or nest to go potty and are in the first stages of house breaking.

Putting puppies on a table and handling and touching them all over will make future visits to the vet or groomer much easier later on. Everything the puppy experiences makes a greater impression on him now that it ever will again. Learning at this age is permanent.

Fourth Period: (8-12 weeks)

This is the time when the owner is going to take over and it is an awesome responsibility. What this puppy becomes as an adult dog will be a direct result of what you do or don't do now. It is probably the most important time in your dog's development. It is also the time breeders fear most. It is the time that the puppies generally leave us and we have NO control over what you do with or to your puppy at this point in his life. We can only guide you and hope that you listen and understand the importance of this stage of your puppy's life.

During the Fear Impact Period any traumatic, painful or frightening experience will have a more lasting impact on the puppy than if it had occurred at any other time. Studies have shown that prior to eight weeks of age, a pup will continue to approach a person, even though that person frightened or hurt him the previous day. However, when he reaches the eighth weeks and is frightened, he will remember and will be afraid of the person and try to avoid contact with them. You should avoid exposing the puppy to new experiences which may be frightening at this age. It is a great temptation to take the puppy out and show him off to friends, neighbors and relatives but that may be too much for him at this age. He may often feel scared, you may not understand why and it isn't important that you do. Just reassure him all is well but in a matter of fact tone. No coddling or reinforcing the behavior by making too big a deal of it. Once you've reassured him, carry on as if there's nothing there. Dogs that are denied socialization during this critical period often become unpredictable because they are fearful or aggressive. It's your job to teach him that he has no reason to be frightened. You should gradually introduce your puppy to new things, environments, and people. Care must be taken to make sure he feels secure in each new situation.

All of your training should be fun and positive and away from distractions. You are now teaching him that he can be a co-worker with you. At this stage, he will be learning at an accelerated rate. He will never be as pliable as he is during this period. His body sensitivity is increasing rapidly and physical punishment should be avoided. If you want your puppy to be a gentle and loving adult, he must be treated gently and lovingly as a puppy. Your tone of voice is your best training tool....good, bad or indifferent. Be careful how you use it.


Fifth Period: 3-5 Months

These weeks are called the Seniority Period or sometimes the Age of Cutting as he is cutting teeth and beginning to cut the "apron strings." He is in the "teen age" stage and will see just how far he can go.

The puppy's basic needs now are training and love, discipline, socialization to humans and other dogs and animals. It is during this time that the dog tries to determine the question of leadership. He will begin to test you to see who the pack leader will be. He will begin to bite you in play or even as a real challenge to your authority. This behavior is natural and a bad thing. However, it is important that you give an appropriate response to those behaviors.

While training is still done in a positive manner, mild corrections for misbehaviors can be introduced. Caution  must be used as the puppy's attitude toward training can become very negative if you are too hard on him. If you are sure the pup knows what you are asking him to do, your method of training must be positive, gentle, but firm. You are not making requests to obey but giving commands.

You must now establish your position as pack leader and not just another sibling. Biting, in particular, must always be discouraged. Other things, such as grabbing the leash or your pant leg or refusing to obey a command he knows well are attempts to dominate you. Avoid all aggressive-inducing play such as wrestling or tug of war. Wrestling, of course, communicates to your puppy that he is allowed to bite you. Tug of war sets you up in a dominance confrontation over an abject. He learns that he can keep objects away from you. Puppies will often growl in rough games. Growling is a dominance vocalization, designed to warn another pack member that they better not confront the growler or he will bite. No mouthing of your body should be allowed  and when it does occur, you should respond with a quick, sharp "NO," or "NO BITE!"

This is also the age for serious mischief and the puppy who has been so good may now chew furniture, tear up the garbage or hide and chew on your shoes. He is cutting teeth and will chew on everything! Give him plenty of safe, chewable items of his own and confined when he cannot be supervised. 

Sixth Period: 4-8 Months


The Juvenile Period, also called the Flight Instinct Period occurs sometime between four and eight months of age. It will last from a few days to several weeks. He is still testing his wings and will venture off on his own and may even ignore you when he is called. How the dog is handled during this stage will mean the difference between a dog that doesn't come when called and one who responds readily. . It is important that the pup learn the "recall" or to come when called before this stage. NEVER chase him. Call, clap your hands and run in the opposite direction. He will usually come flying to catch you and then you can give him praise instead of punishment. Hopefully, you will have already started positive obedience training before this time and your trainer has given you tools to address this flight instinct. Punishment will not work.

It is also at about six months that your puppy begins to "level out." He knows the routine of the household, knows what is expected of him , knows what to expect of you and he does know that you are the boss. This leveling out lasts until he is about 9 months old. He is still a puppy though and needs to be reminded about the rules every now and then. However, by 9 months old, essentially, what you see is what you get. Your dog will become what YOU make him. Puppies take work, but only for a relatively short time. Your hard work will pay off and you will have a loving, well behaved companion.

Seventh Period: 5-18 Months

This is the Adolescence Period. It can appear in smaller dogs as early as five months and in larger breeds, as late as nine or ten months. In giant breeds, it doesn't occur until 12-18 months. In general, the larger the dog, the longer it will take to physically mature. In male dogs, this period is expressed by scent marking. He may become very macho, less friendly and even somewhat aggressive to other male dogs. He may begin lifting his leg in the house, be very interested in girls, tend to roam and is certainly not interested in listening to you! House soiling is a dominance issue. It is YOUR house and it is NOT acceptable.  It will take restricted freedom and lots of supervision if the behavior has been allowed to go on for more than a day or two. With pet males another session of obedience training plus lots of "homework" helps a lot. If caught early on and "convinced" (with whatever method is required) that it is not acceptable the behavior goes away.

In females, adolescence is marked by the onset of the heat cycle. During this three week cycle, she can become pregnant and may attract males. Bitches exhibit erratic behavior during heat. Some are moody and insecure. Others become bold or aggressive. It is for this reason, as well as for preventive health methods. that pet owners should have their puppy spayed or neutered before adolescence rears its head! Adolescence is a good time to start or reinstitute more rigorous training. Be the leader of the pack but also be realistic about your expectations. You cannot expect young dogs to grow up overnight. At this time, dogs are very energetic and exuberant in their responses. They can be "full of beans" but still delightful playmates. You as the owner must learn to channel that energy into learning, working, exercising and playing games.

Another period overlaps with the Adolescent Period. It is called the Second Fear Impact Period and is seen when the puppy is between 6-14 months old. It is also called the Fear of New Situations Period. While similar to the earlier fear period, it is much less defined. It corresponds with growth spurts and therefore, may occur more than once as the dog matures. What marks the Second Fear Impact Period is a change in the behavior of the now adolescent dog. He may suddenly be reluctant to approach something new or be frightened of something or someone familiar. When a dog is exhibiting fear or reluctance, he should not be forced into a confrontation, bullied into being brave or reinforced in his fear through coddling, reassurance, soothing tones or petting.  Force can frighten the dog further and soothing tones only serve to encourage his fear.

Handle it with patience and kindness. The dog must be permitted to work it out for himself without being forced to deal with something he perceives as dangerous. Training during this period puts the dog in a position of success, so his self-confidence will be built up. Desensitize him to the object or situation by gradually introducing him to it and using food rewards and praise to entice him to confront the fearful object or situation. Sometimes letting him stand and look at the object until he feels comfortable or letting another dog take the lead will help. Do not force him but make light of his behavior and encourage him as he begins to deal with his fear. Make sure you lavish praise on his attempts. This phase will pass if handled correctly.

Maturity: 1-4 Years:

Many breeds, particularly the giant breeds, continue growing and physically changing beyond four years of age, so maturity refers to sexual maturity rather than full growth. For the average dog, maturity occurs sometime between one and a half and three years of age.  Small dogs mature earlier and giant dogs mature later. This period can be marked by an increase in aggression and by a renewed testing for leadership. For instance, he may become more turf-protective by barking when someone comes to the door. Teach him how to accept strangers into your home. His friendly play with other dogs may escalate into fighting. This too, can be tempered by training. Interaction with other dogs can be more positive if your dog interacts with dogs of the opposite sex.

Adulthood may be a time when your dog again tests your authority. If he does, handle him firmly, suspend any rough play and continue with training. Additional training classes or private help with training may be a good investment.

This has been an overview of some of the Critical Stages and behavioral changes in puppyhood, adolescence and early adulthood. Other problems arise at these stages which are not the result of the developmental period itself, but are caused by something in the environment or the dog's basic personality. Even so, they are probably aggravated by immaturity and you cannot afford to overlook them. Understanding and training are the keys to success. Some dogs will not exhibit the behaviors listed and others will pass through them at varying rates.

Learning plays a significant role in a dogs development and your dog needs you to play a role in in each stage.