At what age do dogs stop growing?

A new dog owner might get surprised when their pet fully grows up within a year, but some get worried when their dog does not become full-sized even after a year.

Well, this isn't unusual. Most small and medium dogs become fully grown in a year, but larger dogs may take at least two years before they become fully-grown.

This stage of life also marks the need for constant care, diet, training, and socialization for pets; hence, pet owners need to be well aware of their physical and mental stimulation to help them grow better.

But, many people still wonder when their pup has fully grown.

How to tell when your Pup is fully-grown

In most cases, dogs stop growing between 6 and 18 months of age, but some pups continue growing until 24 months.

But not all canines grow at the same rate, with smaller breed dogs growing up much faster than their larger counterparts. This is because dogs with more prominent bones and joints need a bit more time to grow and develop.

Giant dogs like Mastiffs, Great Pyrenees, Saint Bernard, and Newfoundland take the longest to reach full size.

Giant breeds like Great Dane reach their physical maturity within 18 months, but they keep adding muscle and reach their total weight only at age two or three.

Let’s take a look at how long it takes for each dog breed to grow fully.

Small Breeds

Small breeds grow up quickly. They finish growing at around half the age of their larger counterparts.

Small breeds such as Boston Terriers, Jack Russell Terriers, Chihuahuas, and Pugs reach their full-sized framework between six and eight months of age, and they'll keep filling weight until twelve months old.

The small breed dogs also enjoy a longer lifespan compared to larger dogs because they age comparatively slower.

Medium Breeds

Medium breed puppies might take just a bit longer to grow than small breed puppies. You can expect your medium breed dog to reach their physical maturity between twelve and fifteen months of age.

Although they get bigger by 15 months, they usually keep adding weight until they are closer to 18 months.

Airedale Terrier, American Pit Bull, Border Collie, and Standard Poodle are considered medium breeds.

Large Breeds

The large breed is a broad category of dogs divided into two categories; large breeds and giant breeds.

Dogs that reach an adult weight of >50 lb (23 kg) are considered large breeds. The average growth period for large breeds is 12 to 18 months, and they reach maturity between 18 to 24 months, much later than smaller-breed dogs.

Some of the typical large breeds include German Shepherds, Labrador Retrievers, and Weimaraners.

Giant Breeds

The giant breeds are larger dogs like Great Dance, Mastiffs, Great Pyrenees, and Saint Bernard that reach above 45 kg (99lb).

They take the longest to reach full size. Some giant breeds take at least 18 months to grow the basic framework and continue growing in weight until age two or three.

However, these dogs also age quickly than smaller breeds. Mastiffs live only up to 7 to 8 years, and Dogue de Bordeaux lives only until 5 to 8 years.


How to estimate your dog's full size?

One way to estimate their total size is to use an online puppy size calculator.

  • It becomes a bit harder to know how long it takes mixed breeds to become full-sized. You will have to do some guessing by comparing both breed’s weight and size. Not all mixed breeds grow at the same rate.
  • Their gender will determine their adult sizes and weight. Male dogs weigh more and are more significant than female dogs.
  • Puppies experience the most significant growth rate from birth to about six months of age and weigh 30% of their adult weight. You'd know how much your pup will grow at this time.
  • In most pet dogs, sexual maturity occurs between the ages of 6 to 12 months. Smaller breeds reach puberty quicker than large breeds.
  • Smaller breeds tend to have their first estrous cycle (reproductive stage) at an earlier age, while large and giant breeds may not come into heat until they have reached eighteen months to two years of age.

The Stages of Puppy Development

Generally, a pup's development is divided into five stages that start from birth and last until age two.

There are some similarities that all puppies face when growing. This vital info will help you recognize the growth in your pup regardless of breed size.

Neonatal (Newborn - 2 weeks)

Pups at this age sleep most of the day because they need sleep for mental and physical growth. They will wake up mostly to nurse. The birth weight will also double within a week.

Transitional (2 - 4 weeks)

The period between two to four weeks signifies a transitional phase where your pup will open its eyes for the first time, learn to walk, and grow its teeth.

Juvenile (4 - 12 weeks)

Pups aged four to twelve weeks are considered juveniles. Most small breeds will reach their physical maturity within this period. The juvenile period precedes puberty.

Adolescence (6 - 12 months)

Adolescence marks the zenith of their physical and mental growth. Female dogs may begin to go into heat. It also marks the slowing down of physical growth as most breeds are fully grown by this time.

Full maturity (1 - 2 years)

It's the time when your pup entirely becomes an adult dog. They will stop growing bigger but will keep adding weight over time. For giant breeds, this stage marks an important developmental age.


What causes a puppy to stop growing?

It may be worrying when your pup isn't growing regularly or is too small for their age.

There are certain instances when your dog may stop growing naturally, and there are several reasons for their stunted growth, ranging from genetics to intestinal worms.

Here's we'll discuss few common reasons for stunted growth in dogs.

Intestinal worm

Pups that are infected with hookworms or roundworms may experience stunted growth.  If a puppy has an extremely heavy worm infection, the worms can steal enough calories from its body; hence, slowing down its growth.

A poor hair coat, diarrhea, and a big potbelly are signs of worm infection.


Malnutrition is one of the leading causes of stunted growth in dogs. Pups need to eat nutritious food to ensure the healthy growth of tissue cells.

Ensure adequate food and nutrition that supports bones, muscles, and tissue growth in pups. Also, ensure that you don't overfeed your dog or give supplements when they're still growing because too much nutrition can have adverse effects.


You can be assured that strenuous exercise or spaying and neutering does not affect their physical growth; however, you must not indulge them in strenuous exercise. It may damage the growth plates of the long bones and cause abnormal development.

There is a rare disease called pituitary dwarfism in German Shepherds. Some Labrador Retrievers have a genetic component, but these conditions are rare and not generally seen in companion animals.

 Check this infographic for more information. 

To learn more about healthy physical and mental growth in dogs, get in touch with Urban Pet Hospital & Resort, the best doggy daycare in Urbandale.

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