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Puppy Development Stages & Behaviour Into Adulthood

We all want the absolute best for our puppies. That means aiming for good health and a positive attitude (especially when getting together with other dog friends). Let’s look at how to make sure your puppy gets the most out of early life.

Helping your pup become a well-adjusted, resilient adult dog is much easier when you understand the development stages they’ll experience as they grow. Happy and healthy puppies are usually those that have been strongly supported at each phase of development, with their specific needs being met along the way, helping them to complete all the puppy milestones.

If you have all the right information on your puppy’s development, you’ll find it easier to tailor your training to their particular life stage. By doing this, you’ll help ensure your new family member is at home in the world – and whenever their behavior changes unexpectedly, you’ll know exactly what to do.

So, you’re setting yourself up for a lifetime of happy play with your pup as they complete the different puppy stages to grow into a healthy dog. What’s the best way to make sure you know what’s coming?

We've compiled a timeline of puppy growth stages1,2 to help you better understand your puppy’s development as they grow into a healthy and happy adult dog.

The puppy development stages can be splitted as follows:
  • The Neonatal and transitional Stage (0 to 4 Weeks)
  • The Socialization Stage (3 to 14 Weeks)
  • The Pre-Adolescent Period (4 Months to 6 Months)
  • Sexual Maturity (6 Months to 12 Months)
  • Emotional Maturity (12 Months to 18 Months)
  • The Fear Periods ( 8–16 Weeks, 6–14 Months) 
Let’s run through each of them in turn.
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Puppy Stages: 0–7 Weeks

Usually, you won't be able to take your puppy home until they’re around eight to ten weeks old. Even so, it’s still a great idea to get a full picture of the developmental tasks they’ve gone through before you get them in the door.

All those early interactions your puppy has with their mother and siblings are crucial during the stages of puppy development. They’re learning a number of vital lessons during that period just after they’re born, including:
  • Bite inhibition
  • Social behavior: learning how to interact with others
While your pup can learn all of these lessons later in life (if they don’t get the chance in this very early stage), it’s definitely a case of the sooner the better!

The puppy growth stages we discuss here may vary because your puppy is a unique little creature who will develop at their own pace. It is possible to follow what their path will be week by week. (Different breeds will have slightly different timelines, but the order’s the same.)

During this early period in the puppy development timeline, the puppy stages by week (and month) are as follows:

Stage 1: The Neonatal Stage (0–2 Weeks)

Your pup will only have taste and touch1 at this point, being completely reliant on their mother. Puppies in the neonatal phase have very limited movement, which is a slow crawl at most.

So it’s a pretty physically laid-back life for your puppy during this stage, with not much activity at all. They need help from their mother for eliminating faeces (which their mom does by licking their bottoms) and most of their time is spent sleeping.

A lot of this stage is about maximizing body heat. Their mother provides them with all the warmth they’ll need, so they snuggle up close. Even though they can’t do much yet – even open their eyes1 – they can pick up on their mum’s valuable warmth with incredible accuracy. It’s a great skill to have.

Stage 2: The Transitional Stage (2–4 Weeks)

As the puppy’s teeth come through, their sense of hearing and smell1 will develop. At birth, their eyes and ears are sealed shut1. At 2–4 weeks, your new best friend's eyes will begin to open, and their unique personality starts to show, including a wagging tail and the cutest bark attempt you've ever heard!

They’ll also begin interacting with their littermates during the transitional stage, with their eyes completely open1 by five weeks.

The transitional stage also means taking those first, tentative steps away from the mother’s care (not too far yet, though). It’s during this phase that your puppy will begin walking, as well as starting the weaning process1. Yet even though they’re taking their first steps away from their mum’s snuggles, they’ll still frequently scamper back to that warmth.

Around the three-to-four-week mark, solid food should be slowly introduced into the puppy’s diet. Nothing too chewy, and no firm dog biscuits yet – just very well soaked kibble or wet food. You only need to give them a little bit of solid food each day at this stage, because they’re still getting all the nutrients they need from their mother’s milk.
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Stage 3: The Primary Socialization Period (6-8 Weeks)

Socialisation is a really exciting and dramatic time in puppy development. During this stage, the foundational socialising behavior with littermates is built, easing the longer adoption journey to finding a new home. It is also the age when they begin forming bonds with people. With all the rapid brain changes they’ve been having, they’re now mentally developed enough to handle significant change and begin training.

It’s here where your puppy will start to seem less completely dependent, and more like a miniature grown-up dog. This is where they really start becoming interested in playing with their siblings and developing that infectious sense of fun and adventure that will stay with them for life.

Given their brains are still developing, though, it’s important to do all this in a controlled environment. Puppies are easily overwhelmed, and if you try to crowd them with too many things at the same time, they simply won’t be able to take it in. You can still expose them to a lot of new information, of course … just not all at once!

Another important milestone that begins here1 is bite inhibition when your puppy begins to understand that they have teeth – and those teeth can really hurt someone if they’re clamped down too hard.

As usual, the primary way they learn this is from their mom. If the puppy hurts their mother by biting, she’ll let out a yelp with an unmistakable meaning: “Ouch – stop it!” The mother has a great second trick up her sleeve too – if the puppy starts biting during nursing, the mother will simply walk away from the feeding. (Nothing like withdrawing the milk supply to get the message across.)

Your puppy’s siblings will get in on the act too. If play gets too rough with the puppy’s teeth, they’ll also let out a little “Yip!” that means “Back off!” Before long, your puppy will have learned to loosen that grip.

Stage 4: The Secondary Socialization Period (5–12 Weeks)

Here, your puppy’s really getting going. Their brain’s changing, their body’s developing and they’re growing fast.

During this stage, they really begin to be interested in people. After they’ve gained a bit of independence from their mum, they’re looking around for others to bond with. (You.) So, think of this time as a unique opportunity to play with your pup, get to know them and make sure they know you.

Using quick redirection, give your puppy a toy in place of your skin when they try to bite. This will also offer your puppy the opportunity to better moderate their bite strength during playtime with other animals and people.

You can also tame your puppy’s bite with chew toys, although close supervision is vital to prevent them from ingesting the toy and potentially causing a medical issue. For example if your puppy bites too hard, you may stop playing or leave the room for a couple of minutes (before resuming play until the next bite).

All that play fighting with siblings has had excellent effects on your puppy’s motor skills too. They’re no longer a curled-up ball of vulnerable cuteness – they’re a running, jumping and leaping ball of energy!

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Stage 5: The Pre-Adolescent Period (4–6 Months)

The milestones continue, with your puppy becoming even more independent, confident, and curious. It’s a good thing too because they’re now living with you … and they’re hungry for human contact.

Remember, it’s not all fun and games. Training is very important to learn behaviors appropriate to pet dogs (come when called, greet people with paws on floor, walk nicely past the lady with the pushchair (and don’t try to say hi to the baby, don’t chase the mailman etc). They also need to be exposed to lots of different environments to gain confidence with different stimuli (not necessarily to proof your training against distractions, that’s important too, but probably comes later).

Common behaviors puppies display during the pre-adolescent period include:
  • Teething and chewing
Your pup will be getting bigger, and their energy will be significant. However, activity shouldn’t be overdone as the dog is still young and not physiologically (musculo-skeletal) developed to sustain such strain. Therefore the owner should be careful not to put strain on the young puppy and short frequent walks are recommended. It's important to be aware that the fear phase still applies during this time of puppy growth based on exposure to different stimuli and care should be taken to limit over exposure to multiple environments and situations1.

Stage 6: Sexual Maturity (5–12 Months)

More big changes! Your young dog will require a lot of companionship and stimulation during this time, as they’ll get bored easily. Un-neutered dogs also reach sexual maturity around this time (however it is breed dependent and for large dogs could take more than 12 months)

Given all the hormonal changes going on inside their bodies, your young dog will be doing many things they haven’t done before. During the ages of 5–12 months, the following things will happen to your puppy1:
  • Descent of the testicles (males):-by 6 months
  • Scent marking with urine
  • Roaming and ignoring instructions (by not true for all dogs)
  • The first heat cycle (females)-some dogs it may occur later
Be careful if you decide to walk your puppy off-leash during this time because they’re likely to be very vibrant, active and excited. However, this response will depend on the quality of recall the dog has. You can help them out by ensuring their exercise and play areas are safe, with plenty of toys to chew. Socialization and training in public areas are crucial during this period, so take plenty of outdoor time where you can tick both boxes!

Stage 7: Emotional Maturity (12–18 Months)

A puppy’s emotional maturity often develops quicker in small breeds than in larger ones.

Common puppy behaviors between 12 and 18 months3 include:
  • Raising the leg to pee
  • More distinct mood changes
  • A slight dip in energy
When a puppy reaches this age range, it may develop signs of dominant behavior such as a pre-puberty or puberty male showing aggression and territorial behavior to females, bedding and feeding areas3 .However, because dogs are also social beings and co-operate especially within groups dominant or submissive behavior within hierarchical relationships is not always one way since they’ll need to cooperate to live in harmony4.

That’s for good reason, as it’s when a puppy learns to assert itself within their pack. If you’re experiencing this kind of behavior and are unsure of what to do, we suggest consulting a professional trainer or behavioral specialist to lend a helping hand.
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Puppy Fear Stages

While it sounds a bit daunting, the fear period refers to when your impressionable little puppy forms object associations that can be very hard to shake. This works both ways, which is why it’s important to build up many positive experiences with people and animals during this time. The more happy memories your puppy can draw on, the better.

Fear Period (8–12 Weeks)

During this time, your puppy’s irrepressible nature will change into apprehension. That might come as a shock, but it’s to be expected – in this period of huge adjustment, it pays for them to be cautious about the world’s dangers.

Puppy training classes are vital for you and your dog during this time. Training should always be fun, so be sure to avoid punishment no matter what happens. Getting your puppy out into the world to be exposed to as many new things, people and animals as possible is the best way to help them learn. It is vital that you follow your veterinarian’s guidance on vaccination before exposing them to the public. Ensure you keep close supervision of your puppy during interaction with other dogs. A leash can be your friend for this but depending on the training moments of interaction off-leach can also be made available since puppies need opportunities for interaction with other dogs. This can be an opportunity to practice your recall.

Fear Period: (6–14 Months)3

Your puppy’s not out of the woods yet! This is the second period where your puppy’s likely to experience fear, but it unfolds3 a bit differently from the first one.

By this stage, you’ve quite likely forgotten about the first fear period … so the second one could be a bit disorientating. Just remember that even though your puppy’s looking pretty big and strong on the outside, their brain hasn’t finished developing yet.

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Puppy Training

The most important aspects of puppy training is:
  • Socialisation: exposure to dogs and people, that enables the dogs to learn appropriate social behavior
  • Habituation to a variety of different environmental stimuli, so that the puppy can gain confidence with these
  • House training
  • Learning to stay at home alone
  • What to chew and what not
  • And so on
A useful resource you’ll have when training your puppy is a crate. These spaces give your puppy a great sense of security when in your home, and can be introduced as early as 7 weeks old.

Teaching your puppy to use a crate is important, and should start essentially as soon as your puppy is through your front door. Crate training a puppy has many benefits, including helping your puppy to control their bladder and use appropriate signals to let you know when they need to relieve themselves.

Your puppy’s curiosity is at an all-time high during the first 7–8 eight weeks of life, so making short frequent training sessions each day is extremely important. As you’re watching your puppy’s growth week by week, be sure to remain patient and consistent with your puppy for the best results.

At Eukanuba™, we believe in a lifetime of activity and athletic ability. Our diets help build a foundation for performance by using clinically proven levels of DHA that help form smarter, more trainable puppies5. So to prepare for each of the puppy life stages, give your new best friend all the energy and nutrients they need with a quality diet today.

The tips above give you everything you need to follow your puppy’s milestones week by week– and enjoy it with them at all stages of puppyhood.


1.Grandjean, D., Andre, C.,Bacque, H., Bedossa, T., Boogaerts, C., Clero D., Colliard, L., Grellet, A., Polack, B.,Rogalev, A and Haymann, F. 2020. The Dog Encyclopedia. Royal Canin SAS. 930 pp.

2.Scott, JP. and Fuller, J.L1965.Genetics and the Social Behaviour of the Dog. Chicago University Press. 508 pp.

3. Delhasse, J., 1994. Sensory, Emotional and Social Development of the young Dog. The Bulletin for Veterinary Clinical Ethnology 2(1-2) 6-29.

4. Cordoni, G. and Palagi, E., 2019. Back to the future: A Glance Over Wolf Social Behavior To Understand Dog Human Relationship. Animals 9 (11) 991.

5. Kelley, R., Lepine, A. J., & Morgan, D. (2005, May). Improving puppy trainability through nutrition. In Proccedings of Iams pediatric cares symposium, presented at the North American Veterinary Conference, Orlando, January (Vol. 11, pp. 43-56).

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