Do you have a new puppy at home? New puppies are a lot of work. If this is your first go-around with a puppy, you need to prepare yourself. Puppy parenthood is a wonderful thing, but it can easily be overwhelming if you are not prepared for the developmental stages of dogs.
Learning about the dog developmental milestones that your pup will experience is important to raising a happy, healthy, well-behaved dog. It will help keep your dog on the right track, but having this knowledge can also help you know what to prepare for and keep you less stressed.
Developmental stages of dogs
There are 5 different developmental stages that dogs go through before fully maturing. Just be aware that smaller dogs tend to mature more quickly and live longer than larger dogs. So, while the periods listed for each stage are not exact, these are still some good guidelines for the different dog developmental milestones that you can expect to experience with your pup.
Neonatal period (Newborn to 2 weeks)
Dogs are born blind and deaf. So, just like with human babies, you can expect very little from your puppy at this stage. Your puppy really isn’t your puppy yet. Your dog is totally dependent on their mother during this period. This period is full of sleeping and eating.
Transitional period (2–4 weeks)
The transitional period is when the puppy will start to be more in control of themselves and their motor skills. With open eyes and their ears now working, pups can really start to do things on their own. This is when you start to hear that cute little puppy bark and see them starting wagging their tails.
At around 3 weeks of age, your dog will start to take their first, albeit clumsy, steps. This will quickly lead to bouncing around and playing with their siblings. This also is the beginning of the all-important socialization period.
Their puppy teeth also start to come out near the end of this period and by 8 weeks of age, they will have their full set of puppy teeth.
Socialization period (4–12 weeks)
Puppies are ready to explore the world in this period! They now control their bodily functions, and it’s time to socialize! This period is the most important time for puppies to develop their relationship with humans and the world around them.
The latter end of this period is when puppies can be taken from their mother. You should never remove a puppy from its mother before 8 or 9 weeks of age, but ideally, they should stay until around 12 weeks of age.
This period is when you should start to train puppies. They have developed the muscle control to begin to understand potty training. And they can start grasping simple commands.
Important to note is that this is the key period to trauma in puppies. You want to make sure that your puppy doesn’t experience any scary experiences during this time because they can lead to long-term behavioral issues. Your dog will be most impressionable from 8–12 weeks of age. So, you will want to arrange for your puppy to have as many positive experiences with people, other animals, and new situations/places as possible. But more importantly (as much as you can control these things), you should avoid scary or negative experiences. This is a great time to introduce your pup to the vet and arrange “happy” visits and give positive reinforcement for scary things like shots—give treats or make it a game.
Ranking period (3–6 months)
Think of the period between the ages of 3 months to 6 months as the equivalent age as elementary school-age kids. Your dog will have about 90% of their adult brain mass. This is also when your puppy will start to understand your household hierarchy and where they fit into it.
As it relates to training, this is the key time for you to shower your pup with positive reinforcements. This is the period when you are likely to be more overwhelmed with challenging puppy behavior such as chewing and getting into everything they can. Your dog is becoming more independent and assertive. Take lots of deep breaths.
At around four months, your dog will also start losing their baby teeth. So make sure to have plenty of appropriate things for them to chew on.

Adolescence period (6–24 months)
While your dog should be mostly developed by the time they reach this period, you should continue to work with your dog on socialization and behavior training.
Also, prepare yourself for the knowledge that this is the time in a dog’s development that the energy will be at the highest level. Structured activities, lots of exercises, and a healthy diet will help to keep them occupied and at appropriate energy levels.
This is also the time when sexual behaviors will start to show (if you haven’t spayed or neutered, that is). You will also notice that the puppy coat will start to disappear in favor of their new, adult coat.
So, this may be one of the most difficult times for you as your dog pushes boundaries and challenges your authority. But just hang in there!!
According to a study by the National Council on Pet Population Study and Policy (NCPPSP),1 almost 48% of dogs surrendered to shelters are between 5 months and 3 years of age and 96% had not received any obedience training. So, keep up with all of that training. And remember, a tired dog is a good dog.
Usually, by the time your dog is 18 months old, they will have their grownup personality and should settle down a bit.
Adulthood (24 months and up)
You now have a fully developed, adult dog on your hands! Behaviors that they have learned by this stage will be difficult to change, but dogs still can learn! I assure you, you can teach an “old” dog new tricks! During this period, a professional trainer would be beneficial to teaching an adult dog. Trainers are experienced in training older dogs and can be a good source of information for any advice you need for your grown-up dog.
Now what?
Now that you have learned all about the developmental stages of dogs, have you given much thought to dog years? We all know that a 10-year old dog hasn’t aged the same as a 10-year old person. Dog years are vastly different from human years. For many years it was an accepted belief that for every 1 of our years, a dog ages 7 years. It’s not quite as simple as that though.
Learning how dog years work is important for any dog owner. You need to understand how your dog is aging so that you can help him/her age as healthy as possible.
How do dog years work?
If you ask most people, they believe that 1 human year is equal to 7 dog years. But this is a myth of unknown origin. In 1953, a French researcher, A. Lebeau, discovered that contrary to popular belief, simply multiplying by seven doesn’t work. Yes, dogs age faster than we do, but that rule of seven just simply doesn’t work. He looked at life-stage markers (for example, puberty, adulthood, lifespan) shared by humans and dogs. And he determined that a 1-year old dog is equivalent in age to a 15-year old human; a 2-year old dog to a 24-year old person; and after the age of 2, each year of a dog’s life is equivalent to 4 human years.2
In more recent years though, an improved method for studying dog years has been discovered. While it does piggyback off of Lebeau’s original work, it also recognizes that dog breeds and sizes mean different aging rates. For example, large dog breeds (for example, Saint Bernard, Mastiff) age significantly faster than small breed dogs.
A study which was recently published3 used DNA methylation (a process in which methyl groups are added to the DNA molecule) to serve as an indicator of aging. In general, the older a mammal gets, the faster the rate of methylation. The authors compared the DNA methylation rates of 104 Labrador retrievers (ranging from 1 month to 16 years old) to human profiles.
Their recommended formula to show a dog’s equivalent age in human years: Multiply the natural logarithm of a dog’s age in calendar years by 16 and adding 31. Yeah, I had to look that up too. Here’s a natural logarithm calculator if you feel like doing some math. The problem with this analysis though is that different breeds age at different rates so the formula may only apply to Labs.
Dogs are all unique and individual so you really can’t predict with 100% certainty what they’ll do and when they’ll do it. But knowing the developmental stages of dogs is a good guide to help set expectations. All we can say for sure is that if you show your dog love, consistency, and patience, they will show you dedication and devotion that will last a lifetime.
- Salman M et al., “Behavioral reasons for relinquishment of dogs and cats to 12 shelters,” JAAWS, 2000;3(2):93–106.[↩]
- Crockett Z, “The mythology of dog years,” Priceonomics, October 2014, priceonomics.com.[↩]
- Wang T et al., “Quantitative translation of dog-to-human aging by conserved remodeling of the DNA methylome,” Cell Systems, August 2020;11(2):176–85.[↩]
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