When Do Puppies Stop Growing?

Puppies bring energy and joy to any home, but they grow quickly, and that precious puppy phase doesn’t last long. While they’re developing physically and behaviorally, their needs change just as fast. And if you have a new pup running around the house, then you might be wondering, “When do puppies stop growing?” 

This guide will help you understand each stage of puppy growth so you can better support them as they grow into adulthood.

So, when do dogs stop growing?

Dogs stop growing when they reach full maturity, which happens when their growth plates calcify and close. At this point, their bones have reached full adult size.

Puppies grow the most during their first eight weeks of life. Afterward, their growth rate slows, but dogs continue to develop until they’re about 6 to 24 months old. Larger dogs will keep growing for longer, and the exact range depends on breed, sex, and genetics.

Puppy growth development

Learning how a puppy develops can help you better understand your dog’s growth process. Beginning from birth, puppies go through the following growth stages:

Neonatal period (0-2 weeks): This is the period right after a puppy is born. Around 10 days old, their eyes will open. They are fully dependent on their mothers to survive and have very limited senses.

Transitional period (2-4 weeks): Puppies begin to open their eyes, grow their teeth, and continue to develop their senses. They interact with other puppies in their litter.

Socialization period (3-12 weeks): The puppy socialization period begins as they become more aware of their surroundings and start building relationships with their littermates and people. They start playing, using all of their senses, and testing basic skills. It’s during this period (usually 8 to 10 weeks) that new pups come home to their forever families.

Juvenile/testing period (3-6 months): During the juvenile or testing period, dogs explore their world with more curiosity. They exhibit various behaviors like puppy biting and teething as they test their boundaries and explore their fears.

Adolescence (6+ months): At adolescence, your puppy becomes the equivalent of a teenager and begins to experience puberty. It’s highly recommended that pet owners train their puppies and reinforce healthy socialization skills at this stage of growth. It’s also during this time that you might look into spaying or neutering.

Puppies develop much differently than humans, and your dog will pass through dog years at hyperspeed during their first two years of life.

Factors that affect puppy growth

A puppy’s growth timeline varies based on several factors, including breed, size, sex, and genetics.

Breed size

One of the biggest factors that impact your puppy’s growth is their breed and size. Generally, small dog breeds reach maturity faster than larger dog breeds, as larger dogs often need more time to grow and develop their bones.

Genetics

Although you can’t say that a purebred dog grows faster or slower than a mixed-breed dog, it’s easier to predict a purebred dog’s growth because you know their history.

If you know the breed of your dog’s parents, you (or your veterinarian) may be able to make an educated guess as to when they’ll stop growing.

Genetics also comes into play when puppies inherit conditions that affect growth. Conditions like hip dysplasia or dwarfism can cause slower or abnormal growth patterns.

Sex

Similar to humans, the average female dog is smaller than the average male dog. Some research studies also suggest that female dogs reach maturity faster than their male counterparts, but this hasn’t been confirmed for all breed types.

Nutrition

A poor diet can be detrimental to a growing dog. That’s why it’s so important to find high-quality, nutrient-rich puppy food to keep your dog growing at a normal rate.

When feeding larger breeds, pet parents may need to make sure they’re not growing too quickly. Too much calcium in a large breed puppy’s diet can negatively affect their bone development.

When buying dog food, check that it’s formulated for your dog’s breed, size, and age so that they get the nutrition they need. Proper portion sizes are just as important — overfeeding can cause unhealthy weight gain while underfeeding can cause growth issues. 

Adjust food quantity according to your puppy’s breed, age, and activity level to help them grow at a healthy rate. Puppies need to be fed more frequently than adult dogs, as meal timing and frequency can influence their growth and development.

Birth weight and early development

Puppies born underweight may face slower growth and developmental challenges compared to their healthier littermates. Low birth weight can cause feeding difficulties and immune system weakness.

Weaning too early can also cause nutritional deficiencies, leading to slower growth. Proper weaning, usually between 4 to 8 weeks, ensures a smoother transition from mother’s milk to puppy food, supporting healthy development.

Health and medical care

Proper vaccination schedules and parasite prevention are essential to protect puppies from diseases that can stunt growth or cause developmental issues.

For example, intestinal worms, parasites that live in the digestive system, can negatively affect a puppy’s growth. Luckily, these worms are easily treatable with prescribed medication. Some thyroid and heart conditions can also stunt your puppy’s growth, but these are rare.

Routine check-ups ensure that any health issues are detected early and managed appropriately, allowing for normal growth. To avoid these types of health issues, talk to your veterinarian about preventative care and their recommended puppy vaccine schedule.

Exercise and physical activity

Puppies need the right amount of exercise to support muscle development and bone growth. But over-exercise, especially in large dog breeds, can damage growing joints and bones. As a bonus, playtime and socialization with other dogs and humans contribute to a puppy’s overall well-being and development.

Environment

A safe, clean, and stress-free environment is important for optimal growth. Environmental stressors can negatively impact a puppy’s growth. Likewise, extreme temperatures can affect a puppy’s metabolism and energy needs, indirectly influencing growth.

Hormonal factors

Hormones such as growth hormones, insulin-like growth factors, and thyroid hormones play vital roles in regulating the growth process.

Lastly, the timing of spaying or neutering can affect growth, especially in terms of bone development and final adult size.

Puppy development by breed

These are the rough time frames for when small, medium, and large breeds stop growing.

Toy breeds (Less than 15 pounds)

Toy breeds usually stop growing around 6 to 8 months of age.

Because toy-sized dog breeds are the smallest, they mature the fastest. They typically reach their adult size at around six to eight months and reach physical and sexual maturity by their first year.

• Chihuahua: Stops growing around 9-12 months.
• Yorkshire Terrier: Stops growing around 9-12 months.
• Pomeranian: Stops growing around 10-12 months.

Medium breeds (26-55 pounds)

Medium-sized dogs generally stop growing around 12 to 15 months of age.

• Beagle: Stops growing around 12-18 months.
• Cocker Spaniel: Stops growing around 12-24 months.
• Border Collie: Stops growing around 12-24 months.

Large breeds (55-100 pounds)

Big dog breeds tend to stop growing around 15 to 24 months of age.

Some large dogs may take a longer time depending on size, and their dog food can also play a significant role in shortening or lengthening their puppyhood.

• Labrador Retriever: Stops growing around 12-18 months.
• German Shepherd: Stops growing around 18-24 months.
• Golden Retriever: Stops growing around 18-24 months.

Giant breeds (More than 100 pounds)

Due to their enormous size, giant dog breeds take the longest to reach full maturity. They often continue growing until they are 18 to 24 months old, or even up to 36 months in extreme cases. 

• Great Dane: Stops growing around 18-24 months
• Mastiff: Stops growing around 24-36 months.
• Bernese Mountain Dogs: Stops growing around 24-36 months.

Signs that your dog has stopped growing

These signs can help you determine if your dog has reached full maturity and is no longer in the growth phase.

• Growth plates have closed: Once these cartilage areas harden into bone, their growth generally stops. 
• No more height increase: Dogs stop getting taller between 12 and 24 months.
• Steady weight: After reaching adult size, a dog’s weight becomes consistent unless their diet or activity levels change.
• Adult coat development: The puppy coat transitions to a thicker, more mature coat.
• Mature behavior: Dogs show calmer, more predictable behavior, moving beyond puppy-like impulsiveness.
• No more teething: Adult teeth are fully in by six months.
• Sexual maturity: Dogs reach reproductive maturity around the same time as growth plate closure.

A word of warning: Weight gain can happen at any age

While your dog should stop growing by the time they’re 2 or 3 years old, they may keep gaining weight well into their senior years. If your dog is getting too much food and not enough exercise, they can quickly gain weight, increasing their risk of numerous health problems. So, if you’ve noticed your dog is getting a bit chonkier long after they’ve stopped developing physically, talk to your veterinarian about dog weight loss options.

The bottom line: Supporting your dog’s development

When you understand how your pup develops, you can support them throughout the process. Whether your dog is still a puppy or an active adult, you may both benefit from pet insurance. Pumpkin Dog Insurance plans help cover the cost of eligible vet bills in the future, letting you give your pup the best care possible when unexpected accidents and illnesses strike.

---

---