When Is a Dog Considered an Adult?

When Is a Dog Considered an Adult

One of the most exciting things about owning a puppy is seeing your young, cuddly furry friend growing up. But how old do dogs have to be to be considered adults? That’s exactly what I’ll share with you in this guide, so you can look for signs that your puppy is now an adult dog.

Most would say that a dog is considered an adult when they reach 12 months of age. At this stage most dogs have become physically mature at the age of one. But for large-breed puppies, it takes around two years for them to attain physical maturity and be considered adults.

However, just because your puppy is now 12 months and physically an adult, it doesn’t necessarily mean they are “mentally” considered an adult. It might take them until they are 18 months to stop acting like puppies with their erratic and excitable behavior.

Stick around as I cover the different maturity milestones to expect as your puppy grows. I’ll also talk about the signs that show your puppy has entered adulthood, when to introduce them to adult food, and more.

What age is an adult dog?

12 months is generally considered the age of an adult dog. But it’s not as simple as that. If you’ve owned more than one dog in your lifetime, you will know how different they can all be. Some will mature quicker than others.

Here’s my opinion on things, and why whilst some might say dogs are classed as adults at one year, others can have a very different view on things.

Tracking the maturity from puppy to dog adult

When they say good things come in small packages, I think they meant puppies. These lovely little canines fill our lives with blissful, worth-cherishing memories (let’s forget about their stubborn self for a second).

If you have the privilege of being a puppy parent, there’ll come a time when you will stare at your dog in amazement because of how grown they look.

It’s an honor to take care of a puppy and watch them grow into a gorgeous adult dog that still warms your heart just as they did when you brought them home.

Like most things in life, puppyhood has an expiry date. It doesn’t last forever.

If you’re constantly wondering how old dogs should be to be considered adults, you’re not alone. It’s a question that runs through the minds of many puppy owners.

A puppy isn’t considered an adult until they complete their physical development. Most dogs finish their physical growth process by the time they reach one year. This explains why experts generally agree that a one-year-old dog is an adult (they are simply physically mature).

But puppies from large and giant-sized breeds can take up to two years for them to complete their physical growth and be labeled adults.

Small and medium-sized breeds tend to mature quicker than larger dog breeds. That’s because large dogs still have a long way to go as far as bones and muscle development (and eventually attaining their full adult size) is concerned.

When do puppies mature into adult dogs?

Here’s what research says about the physical maturity of different breeds:

  • Small-sized breed puppies reach their adult size when they are around six to eight months old.
  • Medium-sized breed puppies attain their adult size when they hit 12 months.
  • Large-to-giant breed puppies reach their adult size anywhere between 12 to 24 months.

Emotional and sexual maturity in dogs

As much as your one-year-old puppy is deemed an adult dog, they’ll still exhibit typical puppyish behaviors that will tell they have more growing up to do. Reason being, they are yet to emotionally mature.

They may be a year old, but their “grown-up behaviors” will be nowhere in sight!

In general, dogs don’t attain emotional maturity until they’re roughly two years old. At age two is when the dreaded adolescent period ends.

Emotional immaturity is often why most new dog parents wonder whether living with their furry roommates will ever get easier.

If your dog is yet to become emotionally mature, they’ll be difficult to deal with. But when they finally attain emotional maturity, trust me, you will thank the heavens.

You will notice some of the following positive, adult dog-like behaviors:

  • They’re less fearful of strange places or people.
  • Their attention span is much better (not easily distracted as they were during puppyhood).
  • They are quite responsive to obedience training commands.
  • They are more responsive to cues from other dogs around.
  • They don’t display destructive chewing habits and are more respectful of your boundaries.
  • They have a calmer demeanor. They’d rather relax than run around chasing butterflies.
  • They are fully settled into the home and do not give other household pets a hard time.

Besides physical and emotional maturity, your dog will also attain another milestone — sexual maturity. However, this milestone happens before the rest.

Most female dogs are deemed sexually mature when they turn six months old. They go into heat for the first time and have their period.

Large-breed female puppies are an exception, though.

Their first heat cycle starts a bit later— as late as 18 months. Witnessing your precious furry friend get her first period at six months can be a special moment (you might not to comfort them) – it’s a big deal!

Sexual maturity means your not-so-young puppy is capable of reproducing. Although this milestone also comes with awkward sexual behaviors that will leave you questioning your puppy’s innocence.

Their first heat cycle may give you the impression that your puppy is officially an adult. But the truth is, they’re still young at heart — and body-wise, too.

That’s why experts often advise puppy parents to make sure their little canines don’t get pregnant during their first (and even second) heat period.

Though sexually mature, they are still emotionally and physically immature. Nothing awesome about a female puppy dealing with motherhood responsibilities at such a tender age. Plus, their body isn’t strong enough to carry babies.

Apart from physical growth, other maturity signs can confirm to you that your puppy has moved on to the next chapter of life (adulthood).

  • Their mouth will be full of adult teeth. A dog often has teething problems during puppyhood. By the time they hit six months, all their baby teeth will have fallen out, ready to make way for adult teeth. So when you see your little canine pal with grown-up teeth, you know they aren’t little anymore.
  • Their coat’s texture will change. At some point, you’ll notice your puppy sheds quite a lot. The shedding happens as your puppy outgrows their super soft hair to allow the growth of coarser adult fur.
  • They don’t have as many potty accidents as they did before

Transitioning from puppy food to adult dog food

When your little furry friend enters adulthood, their dietary needs change.

You should be ready to change to adult dog food when your small or medium-sized dog hits one year. If you own a large breed, you’ll have to stick to puppy food until they turn two years.

Be sure to consult your vet as you make the switch to protect your canine friend from serious dietary upsets.

You may wonder, why is switching to adult food that important?

Well, here’s the thing. Puppy food is strictly tailored to meet a puppy’s growing needs. Puppy-formulated food has extra nutrients to cater to your naughty puppy’s high energy needs. This food also boosts their bones, muscles, body organs, and joints’ growth.

So, when your young dog is considered an adult, they won’t need all that extra nutrients for their growth needs.

Instead, they’ll require a whole set of nutrients to maintain a healthy and fulfilling lifestyle. Adult dog food will provide just that.

Most dogs eat less when they enter adulthood. As a puppy grows, they need more food since they’re ever active. But as they settle into adulthood, their energy requirements go down. So, they won’t need to eat so much – twice a day.

FAQs on when dogs are classed as adults

Is a 2 year old dog still a puppy?

No, that’s incorrect. A 2-year-old dog is not still a puppy, and instead more than old enough to be deemed an adult.

What age is an adult dog?

A dog is considered an adult dog when they are one or two years old. Small-sized and medium-sized breed puppies are usually labeled adults when they reach one year.

On the other hand, puppies from large-to-giant breeds are considered adults when they turn two years.

Is a 10-month-old dog still a puppy?

Yes, that’s correct. A dog under one year isn’t considered an adult dog.

Is a 7-month-old dog still a puppy?

Yes, that’s correct. If a dog hasn’t reached one year old, they are still a puppy. Adulthood in dogs starts from one year onwards.


All dogs are different.

One of our puppies has just turned 12 months. Now he’s one, you’d think he’d be considered an adult dog. But compared to our 6-year-old dog, their maturity levels are vastly different.

Whilst the puppy can be classed as an adult in terms of size, their brain will still be developing.

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Photo in header via https://unsplash.com/photos/0yHhzZi2wPI

Marc Aaron

I write about the things we've learned about owning dogs, the adventures we have, and any advice and tips we've picked up along the way.

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