A row of puppies laying down next to each other.

When Is A Puppy Fully Developed?

10 mins |

All pet owners love to watch their puppies grow and develop into an adult. As puppies develop into adults, grow in size, and mature, they gain a distinct personality as they age. With all of that said, pet owners normally wonder when is a puppy fully developed anyway?

A puppy is fully developed when the growth plate is closed, and the bones no longer grow any further. A puppy grows to its full size in 6 to 24 months, depending on the breed. Typically, a puppy enters adulthood after 1 year of age. Smaller breeds tend to grow faster compared to medium and large breeds.

Growth Phases Of Puppies

A newborn puppy passes through a number of developmental stages in which it grows both physically, mentally, and socially. In order to develop a healthy, strong, well-behaved, and social dog, an owner must fulfill the needs of nutrition, exercise, socialization, and early training. 

That said, the following are the phases of development from puppy to adulthood.

Neonatal Phase (From Birth To 2 Weeks) 

This phase includes the early development and bonding of a newly born puppy with its dam. At this stage, the puppy can’t open its eyes, the eyes open around 10 to 14 days, and in some cases, it takes 21 days. Puppies rely on their sense of taste and smell and depend on their mother for nourishment and warmth.

Transitional Phase (From 2 Weeks To 4 Weeks)

This is a transition from complete reliance on their mother to standing up, wagging their tail, socializing with littermates, and exploring the world around them.

This is also a time when a puppy opens its eyes for the first time, and a puppy’s senses of hearing, smell, and sight get better. In this phase, teething starts, and a puppy starts biting because their incisors begin to erupt.

Socialization Phase (From 4 Weeks To 12 Weeks)

This is a crucial phase for puppy development. In this phase, a puppy is aware of its surroundings, gets familiar with people, its owner, and, if trained, starts to respond to commands. The puppy also establishes its status within the litter pack. Its curiosity also increases, and so does the play biting called nibbling. 

In this phase, all the puppy’s teeth, 28 in total, will have erupted. The owner will start to wean the puppy as well (a process of gradually shifting the puppy from feeding on its mother’s milk to a dry puppy starter food.)

Juvenile Phase (From 3 Months To 6 Months)

This phase marks the rapid growth of puppies in size; their coat gets developed, their voice becomes heavier, and the puppy enters a pre-teenager stage by the end of this phase. In smaller breeds, almost 75% of the growth is attained during this period. 

Adolescence Phase (From 6 Months To 24 Months)

In this phase, a puppy is now a teenager and gains sexual maturity. A puppy starts to show signs of puberty. For instance, this includes spraying to mark its territory, showing aggression in the case of males, and, in the case of females, erratic behavior is shown during their first heat. 

At What Age Does A Puppy Enter Adulthood?

A puppy in its owner's lap, getting pets.

Generally, a puppy enters adulthood between 12 and 24 months of age, depending on the breed. However, smaller breeds tend to mature earlier compared to larger breed dogs. 

This is the period that marks the complete physical and mental growth of a puppy, and the closure of the growth plates also occurs in this period. A puppy gains sexual maturity and starts showing signs of puberty too. In females, regular heat cycles start, and they are ready to breed.

What Are Growth Plates?

Growth plates, also known as epiphyseal plates or physes, are areas of developing cartilage tissue found near the ends of long bones in growing animals, including puppies. They are responsible for producing new bone tissue as the puppy grows, and they eventually get replaced by solid bone as the puppy reaches its full adult size.

At early stages of puppy life, there is just cartilage that is developed by chondrocytes making up an extracellular matrix. This helps bones to grow longitudinally as the bone gets calcified and cartilage is replaced by bony tissue made of osteocytes (bone cells) as the puppy grows over a period of months.

As a puppy grows, the chondrocytes at the edges of the growth plate divide and produce new cartilage, which is gradually replaced by bone tissue. 

This process continues until the growth plate is completely replaced by bone and the puppy reaches its full adult size. On average, in toy breeds, growth plates close at 6 to 8 months, whereas, in large breeds, growth plates remain open until 14 to 18 months of age.

What Factors Determine The Growth Of A Puppy?

The growth and development of puppies are based on a number of factors: genetics, nutrition, environment, and exercise are some of them. We will discuss all those factors below.


The first and foremost factor that has to do with the growth of a puppy is genetics. Here the breed and genetic pool of the puppy comes into play. A dog gifted with the genes of long and strong bones from its parents will gain height and stature when given proper nutrition. Another factor is gender; males tend to grow larger compared to females.


A properly balanced diet with a high protein percentage of 25% to 30% is needed for the growth of muscles and bones. A diet rich in major minerals like calcium and phosphorus is also important for bone growth. 

An adequate nutrition plan and timely weaning are crucial to gain the height as coded in the genes too. Genes can’t work alone; a balanced diet with a clean and healthy environment is essential for growth. 


Clean, healthy, and disease-free housing with a room for recreation and exercise has a significant impact on growth and development. A stress-free surrounding is important not only for building self-esteem but also serves the purpose of early socializing in a puppy that is crucial for the mental development of a puppy.


Last but not least is regular exercise. It is important for boosting the growth of muscles and long bones by strengthening the muscle fibers and hardening the bones. However, sudden jumps from heights and strenuous running should be avoided in puppies as it may damage the growth plates. Light jogging is healthy in puppies of growing age.

Are There Any Breed Differences In The Growth Rate Of Dogs?

As discussed earlier, not all dog breeds grow at the same rate. The smaller breeds, like poodles, grow at a faster rate and attain their height earlier at 6 months due to the smaller size of their growth plates. However, larger breeds like German shepherds grow a bit slower and attain an adult size at around 12 to 22 months, depending on their bloodline. 

Given below is a comparison of different breeds in relation to their height and age.

Toy Breeds

Here’s the list:

  • Shih Tzu:  height of 8 to 11 inches and gains 90% of growth in 8 months
  • Scottish Terrier: height of 10 to 12 inches gained in 6 to 10 months
  • Pomeranian: height of 7 to 12 inches and stops growing at 8 to 12 months of age.

Medium Breeds

Here’s the list:

  • Samoyeds: Height ranges from 19 to 23 ½  inches, and they stop growing at 12 to 18 months.
  • Cocker Spaniel: height of 13.5 to 15.5 inches and stops growing at 10 to 15 months.
  • Bulldog: height of 15 to 19 inches and reaches full height at 12 months.

Large Breeds

Here’s the list:

  • German Shepherds: height of 24 to 26 inches at around 12 to 14 months.
  • Labrador Retrievers: height of 22.5 to 24.5 inches at 10 to 12 months of age.
  • Rottweilers: height of 24 to 27 inches at 12 to 15 months.

Giant Breeds

  • Bull Mastiffs: average height of 26 to 28 inches, weigh 120 pounds, and gain full size at 18 to 24 months. 
  • Saint Bernards: height of 26 to 30 inches and keep growing till 24 months.
  • Great Danes: average height of 32 to 35 inches and keep growing until 18 to 24 months.

What Are The Factors That Can Stunt The Growth Of Puppies?

There are many factors that can affect the growth of puppies, and some may lead to stunted growth. Improper nutrition, genetics, diseases and disorders, and trauma can stunt the growth of puppies, for example.

Improper Nutrition

A lack of a balanced diet, deficient in essential nutrients, like amino acids that make up the protein required for muscle and bone growth, can seriously halt the growth of a puppy. Moreover, foods deficient in calcium and phosphorus can lead to issues with bones called rickets.


Dwarfism in puppies can be an outcome of a congenital disease. Congenital hypothyroidism, for example, is a rare disease in puppies that can lead to dwarfism as it delays or stops the development of epiphyseal growth plates. Here is a study of congenital dwarfism in Giant Schnauzers. 

Diseases And Disorders

Diseases commonly slow the growth rate in young puppies. For instance, a puppy that survived an episode of viral enteritis will need time to get the required nutrition and will gain weight and height slowly. 

Certain diseases and conditions target the growth directly. For instance, the impact of hypothyroidism on the development of growth plates. Hip bone dysplasia can be genetic or due to the improper growth of both the ball and socket joints of the hip. It could also be an outcome of overfeeding. 

Osteochondritis Dissecans (OCD) is a joint disorder that can affect puppies too. It is caused by articular cartilage that fails to ossify and remains soft. It is characterized by the separation of a piece of cartilage and bone within a joint.  

This process can result in the exposure of subchondral tissue, which has nerves and leads to pain for the dog as it is exposed to joint fluid. This separation can cause pain, lameness, and decreased range of motion in the affected joint.

OCD is typically seen in larger breeds of dogs, such as retrievers and rottweilers. It is thought to be caused by a combination of genetic and environmental factors, such as rapid growth, high levels of physical activity, overfeeding, high calcium intake, and more. 


Lastly, any kind of trauma from jumping or accidents that puts pressure on the epiphyseal growth plates can damage the plates, resulting in shorter bones. 

What Steps Can Be Taken To Ensure The Optimal Growth Of Puppies?

There are certain factors that are not under our control, like genetics, congenital diseases, etc., but we can take some steps to ensure optimal growth and development for our puppies. Here’s what they are.

Providing Ample Time For The Development Of The Maternal-Puppy Bond

Not only does the mother dam provide the puppy with essential nutrients from its colostrum but also the antibodies to protect it from diseases. 

Moreover, early socialization with the mother and the licking behavior of the dam make the pup more stress-tolerant, aiding in growth.

Providing A Balanced Diet 

A balanced diet considering the growth requirements of a puppy should be fed after appropriately weaning a puppy. 

Providing A Clean And Safe Environment 

In the neonatal and transition phases, a puppy is prone to diseases and should be kept in a clean, warm place.

Vaccination Of Puppies 

Early vaccination at 6 weeks of age will protect the puppy from acquiring viral infections like Canine Parvovirus, Canine distemper, Canine hepatitis and Parainfluenza. These diseases can be fatal and even result in the puppy experiencing extreme growth loss while they are recovering.

Adequate Exercise And Training

Lastly, by providing adequate exercise and training, one can raise a well-behaved and healthy puppy. Avoid too much exercise as it may put stress on the delicate growth plates of a puppy only a few weeks old.

Conclusion: When Is A Puppy Fully Developed?

A puppy gets fully developed physically when the growth plates are closed, and a pup has reached its maximum height and weight at around 6 to 24 months.

So, what do you think about when a puppy is fully developed? Let us know in the comments below!

Shahzaib is a qualified veterinarian and professional writer. He is from Islamabad, the capital of Pakistan. He did his DVM from the University of Agriculture, Faisalabad. Being a Veterinarian, Shahzaib has technically sound knowledge of pet health, nutrition, breeding, and housing. He has more than two years of experience in small animal medicine and surgery. Currently, he is working as an Associate Veterinarian in a renowned pet hospital in Islamabad, Pakistan.