When are dogs full grown

Is your puppy becoming an adult dog? It may be hard to tell. If you've had them since they were a young puppy, you'll remember the many changes they experienced: their teeth coming in, learning to play fetch, potty training and socializing.

But the older your pooch gets, the smaller and more subtle their developmental growth becomes. It's important for you, as the pet parent, to understand the changes occurring at every stage of puppy development so that you can keep up with their changing needs as they grow into an adult dog.

When Does a Puppy Become an Adult Dog?

Your puppy won't reach maturity all at once. Like humans, dogs transition from baby to adult in stages, though the transition happens much more quickly for dogs. 

• Sexual Maturity: Most dogs become sexually mature by 6 months when they're still in the puppy stage of development both physically and emotionally. At this point, your pup's sex organs are fully developed, making them capable of reproducing. Spaying or neutering your dog is recommended in order to avoid unwanted pregnancies and adverse behaviors, such as roaming or marking. While the traditional age for spaying or neutering is 6 to 9 months old, the American Society for the Prevention of Cruelty to Animals (ASPCA) explains that healthy puppies as young as 8 weeks old can be eligible. Consult your veterinarian to determine the best age for your pup's unique needs.
• Physical Maturity: Physically speaking, dogs are fully grown by the time they're 1 year old, although large breeds may keep growing until they're 2 years old. When your pup reaches physical maturity, they may still engage in puppy-like behaviors but their physical needs, including the number of calories they need to consume and how much exercise they require to stay healthy, become that of an adult dog.
• Emotional Maturity: You'll know your dog has reached emotional maturity when they stop acting like a puppy or an adolescent and fully settle into the role of an adult dog. Typically, emotionally mature adults are less distractible, better at listening and obeying and have a calmer and more settled demeanor. The precise timing of this milestone differs, but most dogs reach emotional maturity by their second birthday.

How to Manage Puppy Adolescence

In puppy development, the time between reaching sexual maturity and emotional maturity is akin to human adolescence. This can be a challenging stage — at times your pup's behavior might remind you of that of a rebellious teenager. While not all adolescent puppies exhibit behavior problems, it is extremely common. It's important to be patient, but firm and consistent when establishing boundaries and expectations for behavior.

Meeting Your Growing Dog's Needs: Food, Care, Exercise & More

Though they may still have some emotional maturing left to do, your puppy's physical needs become those of a dog once they reach physical maturity. Here's how you should expect to meet your growing dog's changing needs:

• Adult Dog Food: Growing puppies burn through a lot of energy in a day and need specialized food that's high in protein, fat and calories in order to keep up. Once they're fully grown, though, they should switch to adult dog food that will meet their nutritional needs and prevent them from becoming overweight. In order to avoid tummy troubles, it's best to transition slowly over the space of a week, gradually reducing the amount of puppy food while adding in their new adult food.
• Veterinary Care: Barring illness or injury, healthy adult dogs in their prime typically only need to visit a vet once a year for an annual wellness check and, depending on the laws in your state, an annual rabies vaccine. For puppies, however, vets will administer a series of vaccinations starting at 6 to 8 weeks of age, ending with a final dose at 16 weeks, says the ASPCA.

• Exercise: An adult dog's exercise needs vary depending on size, breed, sex, age and health, says the ASPCA. Some small and toy breeds can meet their exercise requirements by simply following you around the house and engaging in occasional play, while larger dogs tend to need at least 30 minutes a day of vigorous activity in order to stay calm and fit. Without the puppy-like urge to romp and explore, your adult pooch may need more structured forms of exercise such as going on walks, accompanying you on hikes or playing fetch in the backyard.
• Dog Supplies: Depending on how big your dog becomes relative to their puppy size, you may need to invest in new supplies. In addition to a larger collar and leash, your grown pup may also need to upgrade to larger food and water dishes, a roomier bed, a larger crate or carrier and new toys that are both bigger and sturdier to withstand rougher play.

It can be bittersweet to watch your puppy becoming an adult — but as much fun as the first year can be, there are few things more rewarding for a pet parent than getting to know the personality of the dog your pup was destined to become. Meeting their changing needs will help set the stage for a loving relationship that will reward you both for years to come.

Amy Shojai, CABC

Amy Shojai is a certified animal behavior consultant, and nationally known authority on pet care and behavior. She began her career as a veterinary technician and is the award-winning author of more than 35 prescriptive nonfiction pet books.

Reviewed for accuracy on September 18, 2019, by Dr. Katie Grzyb, DVM

“At every new puppy appointment, people always ask how fast they will grow and when they will stop growing,” says Dr. Meghan Walker, a veterinarian at Weddington Animal Hospital in Matthews, North Carolina.

The truth is, even your veterinarian can’t say for sure. There is no one single, exact answer for when a dog will hit their full-grown weight.

That’s because several different factors affect your dog’s growth, including their breed and genetics.

Factors That Determine When Your Dog Stops Growing

Your veterinarian will consider several factors when trying to estimate the adult size of a dog, and a few general estimations of full-grown sizes for different breed sizes.

“Genetics are the number one factor that affect growth rate,” says Dr. Walker. “We have an idea, based on breed, but there are a lot of factors that determine it, such as the size of the parents. It’s really guesswork, and the idea that a puppy’s paws will determine their size really is just a myth,” explains Dr. Walker.

Dr. Sara Redding Ochoa, a veterinarian at White House Veterinary Hospital in White House, Texas, adds that growth hormones come into play. Dr. Ochoa explains that growth hormones affect the size that dogs will grow to.

Dr. Walker cites a study in which a large breed dog’s growth may also be affected by neutering before one year of age. This can affect dogs of any size, but in small dogs, their growth is only affected by a few millimeters, while in large breeds, it can be centimeters.   

Average Ages When Dogs Reach Adult Size

Dogs of different sizes are going to mature differently. In general, smaller breeds will hit their full-grown weight earlier than larger breeds.

This is because “it takes more calcium to reach the bones and longer for that development,” says Dr. Ochoa. “The body and bones in larger dogs need more time for the calcium to build up.”

Here are some averages ages for maturation of different breed sizes.

Small Breed Dogs

Dr. Walker classifies small breed dogs as those under 25 pounds when fully grown.

Small dogs include breeds such as the Dachshund, Maltese, Yorkshire Terrier, Toy Poodle, Chihuahua and Bichon Frisé.

Dr. Walker says that small breed dogs typically start growing rapidly at 4-6 months and reach their full size between 10-12 months.   

Medium Breed Dogs

Dr. Walker classifies medium breed dogs as typically between 25-50 pounds when fully grown. Medium breeds include Beagles, Basset Hounds and Miniature Schnauzers.

“We expect medium size dogs to double their size between 8-12 weeks,” says Dr. Walker. Medium breeds reach full growth between 12-15 months.

“Sometimes, they may grow a little after that,” says Dr. Walker.

Large Breed Dogs

Large breed dogs are typically over 50 pounds and include breeds such as Labrador Retrievers, Boxers, Pit Bulls, Golden Retrievers, German Shepherds and Collies.

“Large breed dogs will also double their size between 8-12 weeks, but then the growth slows,” says Dr. Walker. She adds that large breed dogs will typically reach full growth at 18 months.

Giant Breed Dogs

Giant breed dogs include the Saint Bernard, Great Dane, Mastiff and Great Pyrenees. These dogs, according to Dr. Walker, take the longest to develop, due to their huge skeletal frame.

“They will be at full growth potential by 18-24 months, but could take up to three years to reach their full weight,” says Dr. Walker. “Until that time, they may appear lanky.”

By Kerri Fivecoat-Campbell

Featured Image: iStock.com/Lunja