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When Does a Puppy Become a Dog? Understanding the Age of Maturity in Dogs

when does a puppy become a dog

Puppies are cute and cuddly, but at what point does a puppy become a dog or adult? This is a question that many pet owners may have, and the answer is not always clear. This is because the age of maturity depends on several factors, such as breed and the size of the dog. 

Some argue that a puppy becomes a dog once it reaches a certain age or size. Others may believe it’s based on certain milestones or behaviors. For example, not chewing on everything in sight like most puppies do and then forcing you to spritz anti-chew sprays on all your valuables. 

Age is often a factor when determining when a puppy becomes a dog. However, size also comes into play because smaller breeds mature faster than larger breeds. Puppy training and health maintenance books shed some light on the transition period from puppy to adult. 

There are also different types of maturity in dogs that happen at different times. Dogs reach sexual maturity, physical maturity and mental and emotional maturity at different ages.

Physical maturity is one of the dog maturity factors and refers to puppies attaining full breed size. Small breeds tend to grow faster than larger breeds. For instance, a Chihuahua may reach physical maturity at around 6 to 9 months, while a Great Dane may take up to two or even three years.

Sexual maturity is another factor that influences when a puppy becomes an adult. Female puppies may take longer to reach sexual maturity than males. Typically, male puppies reach sexual maturity between 5 to 6 months, while females may reach it at around six months for small dogs and 9 to 12 months for large breeds.

Mental maturity is the final factor in puppies becoming dogs. Dogs mature mentally at different rates, depending on breed and individual development. Mental maturity involves exhibiting behaviors typical of adult dogs, like being less hyperactive and more obedient. Often, large dogs may only mature mentally and emotionally around two years old, sometimes taking as long as three years. 

Smaller breeds may only start maturing mentally and emotionally between 12 and 24 months.

So, as you can see, maturity depends on how you look at it. This is because a dog can sexually mature but still not have reached physical maturity and physical maturity does not mean mental maturity. A fully grown dog may still have the mind of a puppy. Even factors like littermate syndrome may affect a dog’s psychological development.

Overall, the age of maturity in dogs depends on several factors. These include breed, size, and individual development. Physical, sexual, and mental maturity are the three factors that determine when a puppy becomes an adult.

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Age of Adulthood for Dogs By Breed

The age at which a puppy becomes an adult varies depending on the breed. Generally, small breeds mature faster than larger breeds. The following table shows the age at which some popular breed generally reach adulthood:

BreedAge of Adulthood
Great Dane2 years
Saint Bernard2 years
Wolf Hybrid or Wolfdog2 years
Irish Wolfhound2 years
German Shepherd2 years
Labrador Retriever1-2 years
Rottweiler2 years
Border Collie1-2 years
Bulldogs2 years
French Bulldogs2 years
Dachshunds1 year
Yorkshire Terrier1 year
German Shorthaired Pointers1-2 years
Beagles1 year
Chihuahuas1 year
Cavalier King Charles Spaniels1 year
Boxers2 years
Doberman Pinschers2 years
Shih Tzu1 year
Pomeranians1 year

It is important to note that the age of adulthood may not be the same as the age at which a dog is fully mature. This is because most people refer to physical development when talking about dog adulthood. But, emotional and mental maturity are also key aspects that dogs attain long after reaching adult size at around 2 to 3 years old. 

In general, it is recommended to wait until a dog reaches adulthood before starting intense physical activities or training. This allows their bones and joints to develop fully and reduces the risk of injury.

This is why experts recommend waiting past 1 or 2 years before performing the neuter procedure on your male puppies. Early-stage neutering increases the risk of joint issues and even cancers like lymphoma, mast cell tumors, hemangiosarcoma, and osteosarcoma.

Owners should also remember that individual dogs may mature at different rates, even within the same breed. It is essential to monitor a dog’s growth and development and consult with a veterinarian if there are any concerns.

Understanding Puppyhood

Defining Puppyhood

Puppyhood is a dog’s life stage that begins at birth and ends when the dog reaches adulthood. The exact age at which a puppy becomes an adult varies depending on the breed, but it is typically between one and two years old. 

During puppyhood, dogs undergo many physical and behavioral changes as they grow and develop.

Stages of Puppy Growth

Puppyhood can be divided into several stages, each with its unique characteristics. The following are the typical stages of puppy growth:

  1. Neonatal Stage (0-2 weeks): During this stage, puppies are utterly dependent on their mother for survival. They are blind, deaf, and unable to regulate their body temperature.
  2. Transitional Stage (2-4 weeks): Puppies begin to open their eyes and ears to become more aware of their surroundings. They also start to develop their sense of smell.
  3. Socialization Stage (3-12 weeks): This is a critical stage in a puppy’s development. Puppies start to interact with their littermates and learn necessary social skills. They also start to explore their environment and develop their sense of independence. This is also known as the imprinting stage, where puppies bond with loved ones.
  4. Juvenile Stage (3-6 months): Puppies become more active and playful during this stage. They also start to lose their baby teeth and grow their adult teeth.
  5. Adolescent Stage (6-18 months): This stage is characterized by increased energy and independence. Puppies may also start to challenge their owners and test their boundaries.

By understanding the stages of puppy growth, owners can better anticipate their puppy’s needs and provide appropriate care and training.

Puppies Transition to Adulthood

Physical Changes

As a puppy matures into a dog, several physical changes occur. The most noticeable change is in their size. They will start to grow taller and longer, and their weight will also increase. Their bones will become denser and stronger, and their muscles will develop more mass.

Another physical change that occurs during the transition to adulthood is the development of their coat. Puppies typically have a soft, fluffy coat that sheds frequently. As they grow older, their coat will become thicker and more coarse and shed less often.

Behavioral Changes

Along with the physical changes, there are also behavioral changes that occur during the transition to adulthood. One of the most significant changes is in their energy levels. Puppies are known for their high energy and playful behavior, but they will become more calm and relaxed as they grow older. You can read our article on when puppies calm down for more information on their maniacal energy levels. 

Another behavioral change that occurs is in their socialization skills. Puppies are naturally curious and social creatures but may become more selective about the dogs and people they interact with as they mature. They may also become more protective of their family and territory.

Overall, the transition from puppyhood to adulthood is a gradual process over several months or even years. Dog owners must be patient and understanding as their furry friend goes through these changes. 

Factors Influencing Development

Puppies grow up to be dogs, but the rate of development can vary depending on several factors. Understanding these factors can help pet owners provide the best care for their furry friends. Here are some of the critical factors that can influence a puppy’s development:

Breed Specifics

Different breeds of dogs have different growth rates and potential sizes. For example, small canines like Teacups and Chihuahuas may reach their full size in just a few months, while larger ones like Great Danes may take up to two years to get their full size. 


Nutrition is another vital factor that can influence a puppy’s development. Puppies need a balanced diet that provides all the nutrients they need to grow and develop properly. This includes a mix of protein, fat, carbohydrates, vitamins, and minerals. 

Research shows nutrition is especially critical in large-breed puppy growth. Owners must feed their large breed puppies puppy and never adult food to prevent their bones from growing too fast. Fast growth may result in musculoskeletal issues like arthritis, dysplasia, and even cancer. 


The environment in which a puppy grows up can also play a role in their development. Puppies raised in a safe and stimulating environment with plenty of socialization and positive reinforcement are more likely to develop into happy and well-adjusted adult dogs.

 On the other hand, puppies raised in stressful or unhealthy environments may experience stunted growth or other developmental issues.

Common Misconceptions About Puppies Growing Up

Many believe a puppy becomes a dog once it reaches a certain age or size. However, this is not entirely accurate. The transition from puppy to dog is not solely based on age or size but rather a combination of factors like mental maturity and breed size.

One common misconception is that a puppy becomes a dog once it is one year old. While this may be true for some breeds, it is not a universal rule. Smaller dogs tend to mature faster than larger breeds, and the age at which a puppy becomes a dog can vary greatly depending on the breed.

Another misconception is that a dog becomes fully trained and well-behaved once it reaches a certain age. However, training and behavior are ongoing processes that require consistent effort and reinforcement throughout a dog’s life. Even a well-trained adult dog can benefit from continued training and positive reinforcement.

It is also important to note that physical maturity does not necessarily equate to emotional or mental maturity. A dog may reach full size and physical development but still exhibit puppy-like behaviors and tendencies. As a rule of thumb, most dogs attain mental maturity at around 2 to 3 years.

The transition from puppy to dog is not a clear-cut process based solely on age or size. It’s a combination of various factors such as breed, training, behavior, and overall development.

Frequently Asked Questions

When does puppy energy go away?

Puppy energy typically starts to diminish around 6-12 months of age. However, some breeds may take longer to calm down than others. It’s important to remember that all dogs, regardless of breed, need regular exercise and mental stimulation to maintain a healthy and happy lifestyle.

At what age is a dog no longer a puppy?

A dog is generally considered an adult at around 1 to 2 years of age. However, this can vary depending on the breed and size of the dog. Larger dogs may take longer to mature than smaller breeds.

How long is a dog considered a puppy for food?

Puppy food is typically recommended until a dog reaches 1 year of age. After that, they can usually transition to adult dog food. Giant breeds like Wolfdanes and Great Danes may need to eat puppy food longer for 2 years.

When is a female dog fully grown?

Female dogs typically reach their full adult size by 2 years of age. However, they may continue to fill out and mature mentally beyond that age.

At what age do dogs calm down?

Dogs generally start to calm down around 1 year of age. However, some breeds may take longer to reach this stage. It’s essential to provide regular exercise and training to help your dog develop good behavior habits.

Is a 2-year-old dog still a puppy?

No, a 2-year-old dog is generally considered an adult. However, they may still have some puppy-like behaviors and energy levels.

Is a one-year-old dog still a puppy?

A one-year-old dog is considered a young adult. However, they may still have some puppy-like behaviors and energy levels. It’s essential to continue providing regular exercise and training to help them develop good behavior habits.

Final Thoughts

The process of a puppy becoming a dog is gradual and varies depending on the breed and individual dog. While some may consider a dog fully grown at one year old, others may argue that it takes up to two years to reach full maturity. Dog owners need to understand the growth of their pets to provide the necessary care and training.


Tamsin De La Harpe


Tamsin de la Harpe has nearly two decades of experience with dogs in rescue, training, and behavior modification with fearful and aggressive dogs. She has worked closely with veterinarians and various kennels, building up extensive medical knowledge and an understanding of canine health and physiology. She also spent two years in the animal sciences as a canine nutrition researcher, focusing on longevity and holistic healthcare for our four-legged companions.

Tamsin currently keeps a busy homestead with an assortment of rescue dogs and three Bullmastiffs.

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