When Does My Puppy Become an Adult Dog?

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.  Here's what to look for as your puppy matures:

• 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.

Contributor Bio

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.