Puppy Growth & Development Stages - Key Milestones

Here you can see a timeline of your puppy's development and what to expect at key ages of their growth.

Spaniel Puppy

Puppy development: from birth to adolescence

Scientific research proves that growing puppies have different nutritional needs as compared to adult dogs. To give your pup the best start towards an active and healthy life, it’s important to provide them with a diet that’s specifically designed to suit all puppy growth stages. Now, the length of all puppy stages of growth depends upon the size of the dog. Smaller-breed puppies mature more quickly than larger breeds.

Early socialisation and training experiences leave a positive and lasting impression on a puppy which helps it develop into a well-mannered adult dog. The growth of a pup can be divided into five distinct puppy development stages.

1.The neonatal period (first 2 weeks post birth)

At this stage, puppies are relatively helpless and rely on their mother entirely. They spend most of their time either sleeping or eating. Their eyes and ears are closed during birth and open only when they are around 10-14 days old. Moreover, puppies are very sensitive to touch and smell during this stage. 

Neonatal puppies have limited movement and are only capable of a slow crawl. They cannot stand and support the weight of their body.

During this period, a puppy will actively seek its mother. If separated from her, a puppy will start crawling and swinging its head from side to side to find her. At this stage, puppies have very little ability to regulate their body temperature and rely on their mother and littermates for body heat.

In the neonatal period, puppies are only able to feed by suckling from their mother. Urinating and defecating are stimulated by the mother licking the anogenital region, and she keeps the nest area clean by eating any waste products.

Handling puppies for short periods during the first two weeks of life has been shown to be beneficial to their behaviour as they grow.

Let’s quickly summarise some key milestones of puppy development from birth: 

At birth

Your puppy can crawl forwards, but its eyes and ears are closed.

Up to 24 hours

It is essential that puppies consume colostrum--present in the mother’s milk--within the first 24 hours of birth. It contains antibodies that help protect newborn puppies from any diseases.

2 weeks

Your puppy’s eyes and ears begin to open, although vision and hearing can still be poor.

Your puppy is very much prone to worms; hence, they need to have their first worming treatment now.

2.The transitional period (2-3 weeks)

This is the second phase in the puppy growth stages, and the pup shows a rapid change around this time. The young pup starts showing some adult dog characteristics such as displaying social signals by practicing growling. Moreover, it will also respond to light and movement as its eyes begin to open. Since a puppy’s ear canals open during this stage, it starts responding to noise as well. Puppies generally start play fighting with their siblings when they are 2-3 weeks old. 

Puppies start showing an interest in semi-solid food but continue to nurse from their mother too. They can now lap water from a dish.

Anogenital licking of the puppy by the mother is no longer needed now as puppies at this age now begin to relieve themselves naturally away from the nest.

3.The socialisation period (3-12 weeks)

This is probably the most influential period of your puppy’s life as much of what is learned during this phase may last throughout their life. During this time, they develop social skills and learn about their environment. During the latter part of this period, it is essential that your little furry friend encounters as many people, objects and situations as possible which also includes being left alone for short periods, visiting the vet, and travelling in the car.

By week 3, your puppy will start showing a startled response to loud noises; it will try standing and walking too. It might also make the first attempt at barking!

Dogs have two sets of teeth, just as humans do.  Their deciduous teeth AKA ‘milk teeth’ begin to erupt at this puppy stage. 

Let’s look at a few more puppy milestones week by week:

6-9 weeks

At 6 weeks of age, your puppy is ready for its first vaccination. (The second one is between two and four weeks later.)

At 6-8 weeks, your puppy will be fully weaned and enjoying four or five small meals a day.

At 6-9 weeks, puppies usually leave their mother and littermates to go to their new homes. Speak to the breeder about what vaccinations and worming treatments they’ve had. It’s also a good idea to talk to a vet about vaccinations, puppy parties, and neutering before you take the baby dog home. You can take your growing dog out before their vaccinations are complete as long as you carry them and don't allow them to walk on the ground.

8-12 weeks

Your puppy’s food can now be reduced to three meals a day. This age also marks the timing of the puppy’s second vaccination. It is important to check with your vet how many days to wait after this vaccination to take your puppy outside in public areas and meet other dogs.

4.The juvenile period (12 weeks through to adolescence)

By the time your puppy’s growth reaches the juvenile period, most major changes have taken place. All the sense organs will now be fully developed, and the pup’s growth rate will slow down.

However, the juvenile period continues to adulthood, and your pup will need to stay on puppy food until then. This can be any time from one year (for smaller breeds) up to 18-24 months for large and giant breeds. During this time your puppy will still be growing. In fact, it will experience physiological changes that you might not be aware of.

Puppies have similar motor skills to adults by the age of six months, although this can vary according to the environment. And, by about seven months, adult teeth will replace the milk teeth.

You will have to continue socialising your puppy and introduce a training programme. Puppies have a short attention span; hence, keep the training session short, consistent, and fun.

Sexual maturity is marked by the first season in female pups and the ability to achieve a fertile mating in dogs. This usually occurs at around 6 to 7 months, although males may show sexual interest in females before then. However, even though sexually mature, your pup is still not considered an adult dog at this stage.


Puppies mature very quickly, and the smaller the breed, the faster they reach maturity. In small breeds, adolescence can start as early as 5 months. In larger breeds, it can start as late as 9 or 10 months, and giant breeds might not go through adolescence until 12-18 months.

Depending on the size of your puppy’s breed, adolescence will last anywhere between a few months and a year. Once dogs reach maturity, their rate of ageing slows down. Despite the “seven years” myth, mature dogs age at the rate of about four dog years for every human year.

Recognising adolescence in your dog

When your dog reaches adolescence, you might see some or all of the following behaviours:

  • Aggression
  • Plenty of energy
  • Extremely short attention span
  • Poor socialisation
  • Disobedience
  • Wandering
  • Leg cocking (males)
  • Obsessive mounting behaviour

Coping with your dog’s adolescent phase

After all the hard work you have put into your puppy’s training, your dog’s adolescence can be a bit frustrating.

A dog’s instinct tells the animal that it is time to get out and about, leave their scent everywhere, and see off competition. Your challenge is to allow your dog some freedom without getting into too many uncomfortable situations with other dogs and their owners.

Ritual fighting

When adolescent dogs challenge each other, a scuffle is almost inevitable. However, it’s very unlikely to result in injury. Once one has established itself as ‘top dog’, the fight usually ends in a few seconds. And a part of adolescence is learning the rules. So, you don’t need to keep your adolescent dog away from other dogs. It will simply grow up frustrated and poorly socialised. Properly socialised puppies will “mock bite” without causing injury. However, if your dog does injure another, it will need a specialised “bite inhibition” training.

Intensify the training

During this time, it’s essential to keep working on every aspect of your dogs’ training. Give them lots of praise and rewards to boost their self-esteem while they work off some of their extra energy. Don’t give up…adolescence won’t last forever.

FAQs on puppy growth stages

What month do puppies grow the most?

The answer differs from breed to breed. If they’re a toy dog, they will grow the most in the 9th month. If they’re small dogs, they will grow the most in the 12th month. If they’re medium-large dogs, they will grow the most in the 18th month.

What is the hardest among all puppy stages?

Do puppies grow out of biting?

How to discipline a puppy?

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