How to Tell How Old My New Puppy Is

Puppies are sometimes housed at animal shelters.
Puppies kept in bad conditions image by siart from

People who meet and consider bringing home a new canine companion will want to know the puppy's age. When you purchase your puppy from a dog breeder, you are given information about her health, weight, temperament, precise age and parents. However, the age and background are seldom known about puppies who are strays, rescued, adoptable, living in shelters or being sold at pet stores. Estimating a puppy's age is possible if you examine tooth development or observe appearance and behavior.


Step 1

Checking a puppy's teeth is not easy.
Love my puppy! image by Elliot Westacott from

Open your puppy’s mouth carefully so you can look at and feel her gums. When puppies are born their teeth have not emerged, and this phase lasts until they are about 1 month old. This toothless state allows puppies to nurse without hurting the mother dog.

Step 2

Check your puppy’s gums to determine if you can see or feel any signs of teeth. When puppies are about 1 month old, deciduous or baby teeth begin to erupt. Run your finger along the puppy’s gums, and if you feel little bumps, you can estimate your puppy’s age to be around 4 weeks old.

Step 3

Watch your puppy for signs of teething, such as drooling, chewing everything in sight, whining or showing other signs indicating pain and discomfort. The teething phase continues until a puppy is 6 to 8 weeks old. When she is about 45 days old, most of her deciduous teeth are piercing through the puppy’s gums and are very close together.

Step 4

Lift the puppy’s lip gently with your fingers to observe her teeth. If all 28 sharp baby teeth are fully visible and have begun to move apart to make space for her permanent teeth, your puppy is between 3 and 5 months old. Some veterinarians use charts, diagrams and complicated formulas to determine the age of a puppy over time by the type and number of permanent versus baby teeth.

Step 5

Examine your puppy’s mouth. By 4 or 5 months of age, some permanent teeth begin to appear. The first new permanent teeth are the incisors, and you may be able to count six shiny, white teeth with surfaces that are divided into three cusps. This tends to occur sooner in large breeds and a little later in smaller dogs.

Step 6

Look into your puppy’s mouth. Doing so won’t be as painful for you once the baby teeth have been replaced by permanent teeth by around 6 or 7 months old. It is not until your puppy is about 1 year old that her permanent teeth will reach full size. Around their first birthday, most dogs will have 42 teeth -- incisors, canines, premolars and molars -- with 20 teeth on the upper jaw and 22 on the lower jaw.

Eyes and Ears

Step 1

Puppies cannot see when they are born.
women and puppy image by Zolran from

Observe your puppy to try to determine if she can see. If she cannot, your puppy is probably less than 2 weeks old. At birth, wild and domestic canines are blind, and their eyelids are shut tightly. The reason for this is that when puppies are born, their eyes are still developing and must be protected from potential damage and bright light.

Step 2

Watch your puppy and you will notice changes in her vision. When puppies are between 10 days and 2 weeks old, their eyes open, but their vision is not yet fully developed or completely functional. It will take a few more weeks before puppies' eyes mature and their ability to see improves.

Step 3

Spend time with a very young puppy and you will realize that she cannot hear. Puppies are born deaf with their ear canals closed because their ears and hearing are still developing, and sounds and changes in pressure can damage their delicate auditory system. Puppies in this stage of development are under 2 weeks old.

Step 4

Pay attention to small changes in your puppy's responses to the world around her. The ear canals begin to open when puppies are 10 days to 2 weeks of age, and when this occurs, the ears are more fully formed than the eyes are at this stage of growth. A week or so after the ear canals open, when the puppies are approximately 3 to 4 weeks old, their hearing is fully functional, even acute.

Appearance and Behavior

Step 1

Puppies experience something new every day.
puppy with first bone 1 image by Susan Rae Tannenbaum from

Keep track of your puppy's behavioral changes. If you are caring for a very young puppy who is without her mother or littermates, you will not have the chance to observe that at around 3 to 5 weeks old, a puppy starts to interact with her mother and siblings. Between 3 and 7 weeks of age, puppies are developing quickly and you can encourage their progress as they begin to bark, walk, wag their tail, growl and play. Puppies at this age seem fearless and are very curious and active, although you will notice that they are quite clumsy.

Step 2

Avoid frightening, painful, surprising or unfamiliar situations when your puppy is between 7 and 9 weeks of age, because many puppies in this phase become fearful and insecure. Hold off on travel, grooming, meeting strangers or trying out new activities or toys. If you have to take your puppy to the veterinarian during this time, be sure you and the doctor are very gentle and reassuring so the puppy does not perceive the veterinary clinic as an unpleasant and frightening place to be avoided in the future.

Step 3

Comfort but do not coddle puppies during this sensitive time when bonding with her canine family and attachment to her humans reaches its peak. Between 7 and 10 weeks old, being separated from those she feels safe with will cause her to become anxious and cry, often until you are close-by again. Some puppies return to their former confident selves at around 12 weeks old, but for others this phase lasts for a few months.

Step 4

Be patient but firm as your puppy begins experimenting with dominant and submissive behavior between herself, other dogs and people. When puppies are between 13 and 16 weeks old, some become very independent and stubborn. At this age, there may be a lapse in your puppy's desire to please you, and she may stop paying attention and start ignoring even basic training prompts.

Step 5

Resist getting angry when your puppy's testing of both physical and relational boundaries escalates. Beyond 16 weeks of age, puppies need to be patiently taught acceptable behavior or they may continually challenge their humans as they try to figure out their role in the family.


  • When your 3- to 4-month-old puppy is in her willful stage and is not listening to you, be very careful when you open doors or take your puppy to public places. When previously your puppy may have stayed beside you at the park, the beach or in an open field, she may now bolt and not pay attention to you as she explores and plays on her own. This can be a dangerous time, when your puppy could run into a street or get herself in some other kind of trouble, so it is best to keep your puppy leashed and safe during this phase.

  • If you do not socialize your puppy, she is likely to struggle with socialization problems during adolescence and adulthood. Unsocialized dogs may become shy, fearful, aggressive or lacking in confidence in new situations or around unfamiliar people.


  • During the first few months of a puppy's life, proper socialization with humans and other animals is essential. This is the time to expose puppies to anything they might encounter in the future, such as walking on different textures, including tile, carpeting, linoleum, grass, gravel, cement and asphalt, and meeting people of diverse ages, genders, races and abilities.

  • Enroll in a puppy class that combines play and socialization with training. Puppy classes should encourage interaction between puppies of similar ages and between puppies and a variety of humans.

Items You Will Need

  • Birth certificate or breed registration for your puppy
  • Diagram of a dog's mouth
  • Chart describing puppy's dental stages
  • Chart presenting development of a dog's senses
  • Book or article about a puppy's physical and behavioral milestones


About the Author

Maura Wolf's published online articles focus on women, children, parenting, non-traditional families, companion animals and mental health. A licensed psychotherapist since 2000, Wolf counsels individuals struggling with depression, anxiety, body image, parenting, aging and LGBTQ issues. Wolf has two Master of Arts degrees: in English, from San Francisco State University and in clinical psychology, from New College.

Photo Credits

  • Puppies kept in bad conditions image by siart from