If your puppy is growing up fast or if you have an older dog that still acts like a puppy, you might wonder when they are considered an adult. It’s hard to tell when your dog is still a cute little ball of fluff. Puppies become adults faster than humans do, but they still develop in stages.
Different breeds also develop at different times, and some dogs are slower to mature than others. But all puppies are officially considered to be adults by the time they reach 1 year of age. Even at this age, though, their bones may still be developing and they can continue to grow. Some breeds don’t finish growing until they reach 18–24 months of age, even if they’re considered adults.
Growing Differences in Breeds
Once a dog’s skeletal growth stops and the bones reach their final size, you’ll know how tall your dog is going to be. After that, they can continue to develop fat and muscle and fill out more as time goes on.
Small and medium-sized breeds grow quickly. Small breeds can stop growing between 6 and 8 months old. Medium-sized dogs usually reach their maximum growth at around 1 year old.
Large and giant breeds take the longest to grow to reach their full size. These dogs weigh over 70 pounds when fully grown, and their bones take the longest to grow. Many large breeds can continue to grow until they are 18 months old. Giant breeds could take 24 months to reach their full size.
Even if your dog has reached their full size in growth, they could still act like a puppy. Another way to tell that your dog is an adult is their maturity level. Some dogs never outgrow their puppy behavior and continue to stay young forever, having a hard time growing up. On average, though, you can expect to see your puppy maturing around 12–18 months of age.
Maturity Levels in Puppies & Dogs
Puppy development is a process. Dogs can be fully grown but still have puppy maturity levels.
Sexual maturity usually happens in dogs around 6 months old. This is when a dog can physically breed and sire or give birth to puppies.
Physical maturity means your dog looks like an adult dog but is still a puppy. Small dogs reach physical maturity quickly, and large breeds can take up to 18–24 months to finish growing. Physically large dogs that still act like puppies can be difficult to raise because they don’t know how to control their bodies yet. Your dog still wants to play like a puppy, not realizing that they now weigh 60 pounds.
Emotional maturity is reached when your dog is acting like an adult dog and not a puppy. This usually happens as the dog’s hormones even out. Their true adult personality will come through during this stage. Puppies reach emotional maturity at different ages, but you’ll be able to tell when it happens for your dog. They will be more responsive to training commands and calm down easier. They will also listen and respond to cues from other dogs instead of forcing an interaction. Other dogs will consider them an adult dog and respond to them appropriately.
On average, dogs are considered adults when they reach 1 year old, but that doesn’t mean they have reached their full growth or maturity levels yet. Different dogs develop at different times, especially large breeds. They take the longest to become true adults.
Once your dog has reached their maximum skeletal growth, they can continue to develop fat and muscle. They will fill out over time until they reach their full weight.
We may not ever want our puppies to grow up, but they can remain playful and social throughout their lives. Keeping them socialized throughout puppyhood is one way to have a well-adjusted adult dog, whenever they reach that stage.
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