Puppy & Adult German Shepherd

The Lifecycle of a Dog:
Canine Life Stages Explained

Written By Olivia De Santos | Canine Coach, Professional Writer & Video Content Creator.
Edited & Fact Checked By Renae Soppe | Double B.A Journalism & Science. 
Last Updated: 18th January 2024

Whether you have a new puppy or your dog is all grown up, you might be wondering what’s next? What can you expect during each phase of the life cycle of a dog? How do you know when your dog is no longer a puppy?

In this deep dive article, I’ll answer all of these questions and more. Let’s dig in!

Dalmatian puppies and adult dog.

Explaining Dog Life Stages

Before we begin, it’s worth mentioning that there are variations in dog breeds and individuals. The average life cycle does not apply to all dogs. We’ll discuss the variations when it comes to your dog’s size, but there are some minute differences due to genetics as well.

Below are just the general guidelines in order to know if your dog is growing healthily. I will also give tips on things to think about at each stage.


Puppyhood is a broad term. A newborn puppy is very different to a 6month old puppy. It’s the same for babies and toddlers. It’s hardly the same category. There are some more complex terms for each stage of puppyhood that I won’t bore you with. (1) For now, let’s keep things simple and look at the broad strokes of puppyhood.

0-2 weeks

Puppies are born blind and deaf. They can only rely on smell and touch to navigate so they stay close to their mothers. Complete reliance. They can’t move very far or do very much during the first two weeks of life. They’ll rely on their mother’s milk during this tender age and begin the bonding process.

2-4 weeks

After their eyes and ears open, a whole new world is introduced! The puppy will start to develop baby teeth and hone their senses. You’ll also see the puppy developing their own character. Yes - personality develops that young! These two weeks are very important for the puppy to learn to socialise with their brothers and sisters (or “littermates”). They’ll make much more noise around this time - barking, wagging and playing.

4-8 weeks

The puppy will gain more sense of the world around them. They’ll want to explore more as their body grows and their senses heighten. You’ll notice that puppies this young will bite each other and explore their surroundings using their mouths. Puppies can start eating solid foods after around 4 weeks.

“Initially, make gruel by mixing a milk replacer in puppy food soaked in water and place this mixture in a flat saucer. The puppies' noses should be carefully dipped into the mixture two or three times per day until they begin to lap; this usually takes one to three days.” - Krista Williams, BSc, DVM and Ernest Ward, DVM, VCA Hospitals. (2)

Repeat the process of soaking puppy food in milk over several weeks, lessening the moisture levels each time. Eventually, they’ll be able to eat dry puppy food or canned food with no prior soaking.

Though they are weaning off their mother’s milk, they still rely on their mother for learning canine social etiquette.

8-12 weeks

The puppy is now likely weaned from their mother and able to go home with new owners. However, this is a critical part of their puppyhood. They need to keep up the socialisation and eating habits. Puppies this young will eat three-four small meals per day. They need to encounter plenty of different people, dogs, objects, and environments to grow into confident adult dogs.

“Signing up for a good puppy class can help. Look for a class that is based on positive reinforcement, which includes handling exercises, carefully-supervised play, and exercises to prevent fear of loud noises (like fireworks) later.” - Zazie Todd Ph.D., Psychology Today. (3)

 Puppies take very well to obedience training. The sooner you start, the better. You can save plenty of behavioural issues later if you in-still good habits when your dog is young.

12-24 weeks

Now your pup is really coming into their own! Personality is likely fully developed. If you have been diligent with the socialisation stages, they’ll also be social and confident in a wide range of environments. Your puppy’s teeth will start to fall out around this time and new adult teeth will emerge. It’s worth getting some puppy chews to soothe them, or your slippers might be the unfortunate victims of their teething wrath!

That said, there’s no need to transition them off their current favourite food just yet. Your pup will continue to grow happy and healthy on nutrient-rich puppy food. Feeding your dog 3 times a day is okay during this stage. They will start to shed some of their puppy fat. If after 6 months they haven’t lost the puppy weight, consult your veterinarian. (4)

Young Adulthood/Adolescence

Defining the teenage years for dogs is quite tricky. It varies widely from breed to breed. For our purposes today, we’re going to stick to 6months and over.

6-12 months

Your little puppy is now a teenager. And we all know what teenagers are like! Hormones are raging. Behavioural issues can start to show. They are fully independent with formed personalities and quirks. They’ll sleep a lot less during this time.

Most dogs can be spayed or neutered around this age before puberty takes hold.

You can also reduce the amount of food they eat to two larger meals per day.

You can start transitioning into eating adult food but it depends on the breed. Larger dog breeds may not benefit from transitioning until they are well over one year old. That’s because puppy food is so nutrient-dense and promotes the growth of healthy bones. Larger dogs need that vital extra support until they are fully formed into adulthood. Smaller breeds can transition off puppy food as early as 9 months old. If in doubt, contact your veterinarian.

12-24 months

It’s fair to call this early adulthood for many dogs. We’ll discuss the nuances of this a little later. Your dog is bright, energetic, and healthy (hopefully!). You may notice some behavioural changes around now but keep up your obedience training from puppyhood. The more you reinforce the training, the better behaved your dog will be.

Your dog should be eating adult food appropriate for their dog breed and size.


Now that your dog is two years old, they are well into their adult lives. You may notice that your dog calms down a little in mid-adulthood, but this isn’t the case for all dogs. I have a 13year old Podengo that we affectionately label the Eternal Puppy. He acts as if he is 6 months old still. He can run just as fast and jump just as high (but he’ll have to rest for a while afterwards!).

If your dog is settled into a solid routine, they should be well-behaved and sociable at this stage. It’s important to keep your dog stimulated with activities and daily walks. You should reinforce your training practices too.

Pregnancy and Procreation

Of course, this life stage doesn’t apply to every dog, but I thought it’s worth a mention! After all, it’s a dog life cycle. A key part of any animal’s life cycle is procreation.

Female dogs reach puberty at different ages depending on the breed. The guesstimate is 6-9months old. When your dog is in heat, the oestrous cycle is in motion. Your dog’s vulva will engorge, and they will bleed.

“Most dogs come into heat twice per year, or about every six months, although the interval can vary between breeds and from dog to dog.” - Ryan Llera, BSc, DVM; Cheryl Yuill, DVM, MSc, CVH, VCA Hospitals (5)

The oestrous phase lasts around 10-14 days. If your dog is impregnated during this time, they will be pregnant for about 63 days. (6)

Senior Adulthood/Twilight Years

Ah, the twilight years. Your dog is at the tail end of their life. Some dogs will display health issues, aches, and pains as we all do when we get a little older. Eyesight and hearing can dim. You can use supplements to keep your dog as mobile and healthy as possible as they grow older. Cod liver oil always seemed to help my golden oldies stay active. They will likely want to exercise and play less, but they’ll still need stimulation.

Older dogs also sleep far more than middle adults. In their final years, they may sleep as much as puppies do!

I recommend switching your dog to food made specifically for senior dogs. They’ll contain specific vitamins and supplements to support their joints and cardiovascular health.

How Does The Dog Life Cycle Differ For Different Dog Breeds?

In the life stages above, I labelled it as the life cycle of a dog. But the truth is more that this is the “average life cycle of a medium-sized dog”. As with all animals, there are various factors that go into maturity. Some elderly dogs that act like puppies for their entire lives, I have one such rascal! Different dog breeds grow at different rates too.

Medium dogs generally follow the stages explained above. So let’s consider the other three sizes of dog, for balance:

Life Cycle Of A Small Dog

Smaller dogs mature much quicker than any other type of dog. This goes for tiny breeds too! You can expect a small dog to take between 9-12 months to grow into a full adult depending on the breed and weight class. Typically, the smaller the dog, the faster they mature. Though many small and tiny dog breeds still take around 12 months to grow out of puppyhood.

Life Cycle Of A Large Dog

Larger dogs take longer to mature than their small and medium counterparts. It can take 12-18 months or longer for some breeds to be classed as full adults.

Life Cycle Of A Giant Dog

Giant dog breeds take the longest to mature. A Newfoundland puppy can still be considered a puppy/teen when they are 2 years old! It’s fair to say that most dog breeds, regardless of size are fully matured by the time they are 2 years old. Giant dog breeds are leading that curve by being the last to grow up.

My Final Thoughts

Dogs can live happy, healthy exciting lives. To support your pup through every stage of their life cycle, make sure that you consistently learn what they need. Just like humans, we require different diets, routines, and exercises at each phase of our growth.

Your dog is no different. So enjoy growing together and give your dog the best life they can live!


Is 1 year old dog a puppy?

Yes and no! It depends on your dog’s breed and size. Large and giant dog breeds mature much slower than smaller dogs. Most medium and small dog breeds are fully matured by the time they are one year old. But that’s not the case for every breed. Larger dogs can take up to two years to fully mature. Look at charts for your dog’s breed to check the age that your dog is classed as an adult.

How long do dogs live?

Your dog’s life expectancy will depend on the breed. (7) As a quick guide:

  • Small dogs on average live from 12-17 years
  • Medium dogs on average live for 10-15 years
  • Large dogs on average live for 9-12 years

How do you know if your dog is no longer a puppy?

There are a few indicators to suggest that your dog is fully matured.

If they haven’t been spayed or neutered yet, they will enter their heat cycles.

They no longer have their baby teeth.

They are at the recommended weight for adult dogs of the same breed naturally. Or rather, they didn’t grow to that size because of overweight issues or overeating. It was a natural progression to a new maintenance weight.

Temperament generally isn’t a good indicator of physical maturity as some dogs can be mentally young for a very long time!

Do dogs go through puberty?

Yes, they do! The age at which they start the process depends on the breed. Small dogs will enter puberty a lot sooner than large dogs. As a rule of thumb, most dogs are pubescent from 9-18 months. During puberty, your dog may scent mark, show aggression and have erratic behaviour. If you aim to spay or neuter your dog, contact your vet to learn when the best time is to do this.


  1. “Puppy Developmental Stages and Behaviour”. Regina Humane Society. Retrieved February 9, 2022. https://reginahumanesociety.ca/programs-services/municipal-services/alternatives-to-admission/dog-behaviour-tips/puppy-developmental-stages-and-behaviour/
  2. Williams, K. Ward, E. “Raising Puppies”. VCA Hospitals. Retrieved February 9, 2022. https://vcahospitals.com/know-your-pet/puppy-raising
  3. Todd, Z. November 14, 2019.  “The Life Stages of Dogs: From Puppies to Seniors”. Psychology Today. Retrieved February 9, 2022. https://www.psychologytoday.com/us/blog/fellow-creatures/201911/the-life-stages-dogs-puppies-seniors
  4. Mansourian, E. August 15, 2021, “Puppy Feeding Fundamentals”. American Kennel Club. Retrieved February 9, 2022. https://www.akc.org/expert-advice/health/puppy-feeding-fundamentals/
  5. Llera, R. Yuill, C. “Estrous Cycles in Dogs”. VCA Hospitals.  Retrieved February 9, 2022. https://vcahospitals.com/know-your-pet/estrus-cycles-in-dogs
  6. Burke, A. May 3, 2021. “How Long Are Dogs Pregnant?”. American Kennel Club. Retrieved February 9, 2022. https://www.akc.org/expert-advice/dog-breeding/how-long-are-dogs-pregnant/
  7. Burke, A. July 14, 2016. “How Long Do Dogs Live?”. American Kennel Club. Retrieved February 9, 2022. https://www.akc.org/expert-advice/health/how-long-do-dogs-live/

Olivia De Santos

Olivia De Santos is Gentle Dog Trainers Canine Coach, Professional Writer and Video Content Creator.

Olivia has over 10 years of experience writing professionally and is a dog Mum to Pip, her Podengo and Blue, her Flat-coated Retriever. She loves writing pieces to help people to be better dog owners.

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