When Does My Puppy Become An Adult?
Puppies grow quickly. Before you know it, that cute ball of fluff with boundless amounts of untamed energy has grown. They are substantially bigger than the day you first laid your eyes on them, and they probably listen to you a lot more too. Before you know it, your dog is on the cusp of the most important milestone of their life – adulthood.
Most puppies will become adults between 12 and 15 months old, although larger breeds of dog (anything over 100lbs) may not become adults until they are 18 months old. By this point, your puppy should be physically mature. Although, they may still retain some puppy-like traits.
On this page, we’ll give you an overview of the three key growth milestones in a dog’s life. These are the points where a puppy will take on some of their final adult traits. We’ll also let you know when you should be switching your puppy from puppy food to adult dog food. This won’t necessarily coincide with when they reach adulthood. In fact, it happens a little bit before.
Why You Need to Know When Your Puppy Becomes an Adult
Anybody that has ever raised a puppy will know that the adult version of their dog is completely different. We have seen incredibly active puppies become chilled-out, mellow dogs once they reach adulthood. We’ve seen quieter puppies become much more active in their early adult years. It is very tough to predict what will happen once your dog hits emotional maturity.
As an owner, it is important that you know when your puppy is almost an adult. You’ll need to feed them different foods, and they may need to be handled in slightly different ways. This includes how you handle their training (adult dogs can be trained for longer periods of time).
You will need to pay extra special attention to their nutritional requirements. The food eaten by a puppy is not suitable for an adult dog. Puppies need a ton of protein and fat to grow, while adult dogs need considerably less. You don’t want to be feeding an adult dog puppy food because they will gain weight. It could make them sick too.
As we said, every dog breed is different. They become adults at different ages. This leads us neatly to the next section.
When Does My Puppy Become an Adult?
This isn’t an easy question to answer. Yes. Most people will say that a puppy becomes an adult once it hits a year old. This doesn’t quite tell the whole story, though. Dogs age at wildly different rates. While one puppy may reach key growth milestones when they are a year old, another may take up to two years.
It all depends on how you define ‘adulthood’ in a dog. Technically, there are three growth milestones that, once hit, you could say that your dog is officially an adult. Although, most dog owners will look at just one of them:
Sexual Maturity
This is the first ‘adult’ milestone that your dog will reach. Around 6-12 months old, your dog will be sexually mature. At this age, it could start producing offspring. Although, breeders will rarely breed dogs this young. Most will wait until the dog is fully-grown due to the risks associated with breeding puppies. Not to mention the fact that the dog isn’t mentally mature enough to raise offspring.
Physical Maturity
This is where most people claim that a puppy becomes an adult. Physical maturity is when your dog is fully-grown. When this happens will depend on the breed and the size of the dog. The larger the breed, the longer it will take that dog to reach physical maturity.
Dog breeds with a maximum weight of 50 lbs stop growing at the 12-month mark. However, larger dogs may not hit physical maturity until they are 18-24 months old.
Mental Maturity
The third stage is mental maturity. This happens after the other two stages.
Puppies don’t just magically become mentally mature dogs when they are fully grown. For the first couple of years of a dog’s life, they will still be exploring the world, pushing boundaries, and will have bundles of energy.
This means that a young fully-grown dog will still be displaying puppy-like behaviors. They’ll be harder to train, they are easier to distract, etc.
Mental maturity can hit at different ages. It is rarely about the breed here, and more about how the dog was raised. Most dogs should become mentally mature at 2 years old.
Signs Your Puppy May Be Becoming an Adult
As your puppy moves into adulthood, you’ll start to notice a few changes. Some of these may be gradual changes that are tricky to spot, while others will be glaringly obvious. We figured that we would run you through some of these changes.
The following changes (some of which happen gradually) indicate that your puppy has finally outgrown their youth and is well on its way to being, or currently is a fully-grown adult dog.
Your Dog Becomes More Obedient
Puppies are boisterous. While you can train a puppy (and you absolutely should train a puppy), it is incredibly difficult. Puppies are constantly distracted. Training them for more than a couple of minutes at a time is a challenge.
As your dog gets older, you’ll find that they listen to you a lot more. At around 12 months old, you’ll find that it becomes a whole lot easier to get your training to ‘stick’. This is the point when you can really start to shape the behavior of your dog.
Your Dog May Act Out a Bit More
As your puppy transitions into adulthood, it starts to act a bit like a teenager. They start to act out a little bit, trying to push your buttons. Some suggest that this is because the dog is much more confident in ‘demanding’ things from you. While a puppy is going to just go with the flow, an adult dog may try and get you to cater to their every whim. They just want to test your limits.
Some have noted that between 18 and 24 months old (sometimes a bit later with larger dogs), the dog may get slightly more aggressive. Not to the point where it is violent or anything. It just may bark, growl, or jump about a lot. You really must deal with these behaviors quickly.
Your Dog Will Start to Be More Relaxed
Adult dogs tend to be much mellower than puppies. They no longer have a ton of energy to bounce around 24/7. Even the most excitable puppy is content just to lounge about on the sofa once they reach adulthood.
You may even notice that your dog becomes less playful as they become an adult. Although don’t worry. Your dog isn’t going to lose that fun-loving personality. They just won’t play with you as often. For many, this could be a welcome break.
They’ll Start Noticing the Other Sex
If your dog hasn’t been spayed or neutered, it’ll start paying more attention to the opposite sex, for obvious reasons. If you don’t plan on breeding your dog, then you’ll need to make sure that they have been desexed before adulthood (6-12 months is a good age).
Your Dog Can Switch to Adult Dog Food
As your puppy reaches adulthood, their growth rate will slow down massively. A few months before the dog is expected to be fully-grown, you need to change their food to ‘adult’ dog food.
As we said earlier, it is important that you make this switch at the right time. You don’t want to be too early or too late. Get things wrong, and the health of your dog could be seriously impacted. Puppies switched too early won’t grow properly, and adult dogs switched too late could have health problems e.g., obesity.
When Should My Puppy Eat ‘Adult’ Dog Food?
Ideally, you should switch your puppy over to ‘adult’ dog food a few months before you expect them to be physically mature. As you know by now, this will depend on the size of your dog.
Here are some guidelines:
| Dog Weight | When To Switch to ‘Adult’ Dog Food |
| Under 20lbs | 9 months |
| 21lbs to 50lbs | 9 months |
| 51lbs to 100lbs | 12 months |
| Over 100lbs | 13-15 months |
We cannot stress enough that these are just guidelines. When it comes to switching from puppy to adult dog food, you can’t just wing it. Talk to your vet. They’ll tell you when you should be making the switch.
Final Thoughts
Your puppy will become an adult when they reach physical maturity i.e., they are fully grown. When this happens will depend on the breed. Smaller dogs become adults within a year, while larger dogs (over 50 lbs) may take 15-18 months. But remember, just because your puppy is a fully-grown adult, it doesn’t mean that those puppy-like behaviors will disappear. In fact, your puppy likely won’t be mentally mature until they hit 2 years old. This will be long after you have made the switch from puppy to adult dog food.
