The Dog Growth Cycle, Stages Of Life And Aging

A dog’s average lifespan is on average 12 years.  This changes slightly from breed to breed so take it with a grain of salt, so to speak. Within this time, a dog experiences the stages of life in the dog growth cycle.

With dog years relating to human years at an average rate of 7:1, it is interesting to think of when a dog might be teen-aged.  Or when can a dog have puppies? If your dog is 10 years old, does that make it a senior? We’ll explore all these and more in ‘A Dogs Growth Cycle, Stages of Life and Aging’.

How A Dogs Growth Cycle Works

A dog’s growth cycle is much faster than humans.  The dog’s gestation period is considerably shorter than humans.  And dogs are generally sexually mature anywhere from 6 months to a year.  That’s ridiculous compared to the 12-13 years it takes for most humans to reach the age where technically they could reproduce (Source: What is the age of human’s biological adultness? – Quora).  Of course, in most countries, it is unheard of that someone 13 years old has a child, but it happens more often then most of us would think.

Stages Of Life


A female small dog trying to get a larger medium sized male dog to mate in this file photo.
Whoa There, Little Girl!

The fun part, right?  Well, it is for us humans, but dogs on the other hand, who knows?  The point is this is the first stage of a new life. Life is conceived between two consenting adult dogs.  At least, that’s what we’d like to think. But it may not be so much fun.

Male dogs, unlike humans, do not become erect before copulation.  They become erect during copulation, after penetration. And this ‘locks’ the male to the female.  This can last for 5-20 minutes. You can understand how a female dog copulating for the first time could become quite distressed in having the male locked in place for minutes.  She may even try to run away.

This is why many breeders recommend calming first-time dogs to help them through the process so no one gets hurt. 

Pregnancy – Development

Once the deed is done, the usual story takes place and puppies are growing inside the female dog’s womb.  The usual litter size is from 3-4 for very small breeds, to 5-6 for medium breeds and up to 15 for very large breeds of dogs.  As you can guess, the size of the breed relates to the number of puppies, generally speaking, that is.

Gestation typically lasts about 63 days.  The question is which day did it start precisely as sperm can live in the fallopian tubes for up to 10 days or so.  The take away here is to assume about 60-70 days gestation period.

Birth & Newborn

After the gestation period is up, the female dog gives birth to her litter.  This is a special moment for both infants and mothers with an eternal bond forming between them.  You should not handle them for about 3 weeks. The basic rule is you can start handling them once they can walk and have their eyes open.  Newborn puppies are very fragile and they need their mothers to care and love. The mother will stay with them almost constantly except maybe to go to the bathroom.

Mama Tip:  Keep an eye on the mother to make sure she eats within 24 hours of giving birth.  She should be hungry and if she does not eat within 24 hours of giving birth, it could be a sign of a complication so consult your veterinarian. 

Newborn Tip:  The newborn puppies need some extra care and this should be set up before the mother is going to give birth.  One recommendation is to help keep the puppies warm. Newborn puppies have issues with regulating their body heat and according to the Merck Veterinary Manual, you can use a heat lamp in the area to keep the puppies warm.  This is because puppies cannot control their thermoregulatory mechanisms until 4 weeks of age.  Just make sure you have a cooler area in the pen they can wiggle to if needed as well.

Newborn Puppy Checklist

  1. Check and record weight and health 
  2. Monitor temperature of the puppy pen
  3. Monitor mother’s eating
  4. Watch for strange behavior like refusal to nurse puppies
  5. Register the puppies

Infancy aka Puppyhood

The cutest puppy ever is shown sleeping in the arms of someone, in this file photo.
Awww!!! The Cutest Puppy Ever!

This is the cutest, by far, phase of a dog’s life cycle.  Who doesn’t love puppies? The chubby, awkward, silly and playful smaller versions of their adult selves.  I love puppies. Puppies have a way of bringing joy into the room. And love, and laughter. Everyone should get to experience the puppy phase of the life of their dog.  Not to say you can’t adopt an older dog, a worthwhile and noble cause, in my opinion.

The puppy stage of a dog’s life is from being born until about 6 months old.  This naturally begins with birth and being a newborn. The puppy should be left with the litter and mother for about 6-8 weeks after birth.  The mother will typically not want to leave the puppies alone for any length of time. It can even be that you might need to collar and drag out the mother to use the grass outside.  

Instincts Of Mother Dogs

Often the motherly instinct is so strong the mother may even disregard leaving her puppies to get food or urinate/defecate as mentioned.  Don’t feel bad about suggesting such behaviors to help your mama doggy. This stage is vital to the proper socialization of the dog and house training. 

Don’t forget about the fact that the puppies need to be kept warm during the first 4 weeks of life.  They can’t regulate their body temperature at that age, keep in mind.  

You should be weighing, and recording the puppy’s weight from birth, 12 hours, 24 hours, 36, 48, 72 and so on for the first month.  I recommend this so you can see the growth progress. The puppies should show continuous growth during the first 6 months and keeping a record of it is important to track the dog’s health.

Puppies’ eyes will be shut for about the first two weeks, according to Ashleigh Veterinary Centre.  During this time, the behavior should be to eat and spend about 90% or more of the time sleeping.  If this isn’t the case, something could be wrong and you should seek out your local veterinarian immediately.

Dog Health Watch Tips

Health Watch Tip #1:  Keep an eye on and monitor the mother dog.  Not only do you have to pay attention to her eating habits, digestive function (going to the bathroom, urinating, defecating), but you also need to monitor the mother dog’s breast condition.  If the mother dog has inflammation, tenderness or hardness, seek a veterinarian immediately. It could be the cause of an infection that could be spread to the litter and potentially cause death.  Litters have been known to die out completely within 24-48 hours due to nursing complications when newborn. Again, keep an eye on things. I’m not trying to scare you, just prepare you. Being prepared can make emergencies go a lot smoother.

Health Watch Tip #2: Another thing to watch for is if the mama dog is panting and moving ‘with stiffness’.  She may be suffering from a very serious calcium deficiency of the blood and could need emergency treatment.  This has the best chance of happening between 3-5 weeks of the puppies age due to being the heaviest milk-producing phase.

The basic rule I think when dealing with the care of a pregnant dog and/or the newborn puppies is to consult the veterinarian during the process and keep them up to date about the expected delivery date so they can advise you of whom to call in case their assistance is required.   “Plan it out and have no doubt.” Jeremy Shantz (coined it right there, did you see that?).  


Comically, adolescence in dogs can be similar to humans.  The ‘teenager’ often forgets previous training, acts out in with stubborn behavior and can disregard instruction.  This phase typically lasts from about 6-8 months old until 1.5-2 years old, depending on the breed and the particular dog.  Like people, every dog is slightly different.

The key to a well-behaved adult, according to the American Kennel Club, it is important to maintain discipline during the puppy/adolescent phases:

One common mistake is giving your puppy too much freedom too soon. Young puppies have an innate desire to be near you, and this gives owners a false sense of security. As your puppy gets older and more confident, he will likely no longer stay close by, and it may feel like any prior training has disappeared!

Your Adolescent Puppy and Changes to Expect By Breanne Long, American Kennel Club
A puppy running with an adult dog.  The adult dog carries a large branch in its mouth.
Puppy Learning From Adult Dog


Ah, finally we’ve reached the adult dog.  This is the quintessential phase of what a dog is known best for.  Loyalty, intelligence, well-behaved and well-trained. These are the aspirations of any dog owner.  But anyone who has raised a dog will tell you, they have their personalities and there’s not a whole lot you can do about that.  Of course, who would want to? Individual character makes the dog a loved member of the family! Their individual quirks are what we secretly love about our furry friends.  Its what makes them more ‘human’. And brings us closer to understanding each other through association.

Speaking of association, by the time the dog has reached the adult phase of life, they have associated with their human family and bonded with at least one member of the household more than others.  This is the typical behavior of a dog. They often latch on to one person a little more than the others. Sometimes this is for selfish reasons just like in the movie As Good As It Gets (the bacon coaxed the dog away from its original owner by another person – but who doesn’t love bacon?).

When Does Adulthood Start For A Dog?

The adult phase of a dog’s life lasts from the point adolescence is over (usually between 1-2 years of age) and lasts until death, technically.  Although old age is indeed a stage of adulthood, we separate it here for the sake of health concerns.  

During the adult phase of the dog’s life, they will act in a more mature manner than they did in their adolescence.  Combined with the training received during the puppy and adolescent phase, this should be the most stable phase of the dog’s life.  If we were to assume that adolescence ended in a dog at approximately 2 years old, and if a dog were to live to 12 years, then we would assume that adulthood would be from 2-10 years of age.   This leads us to the inevitable final stage of a dog’s existence.

A golden retriever in its elder years  is shown resting in this photo.
Ahh, the Golden Years…


The dogs final years of life, or old age, usually take up the dog’s last 2-5 years of life, depending on how the dog’s health was during its primary adult years.  If a dog had previously encountered disease or health problems, the old-age stage could be pronounced, exaggerated, extended or shortened. There are many variables that determine the quality of life for an elderly dog.  And just like with us humans, we all hope for and want the elderly years to be as youthful as possible.

The elderly stage for dogs can be characterized by some apparent physical changes as well as changes to the dog’s behavior.  Dogs that are old-aged often display signs of slower movement, a more relaxed demeanor and often also their coat changes color, just like people have the issue of hair going white, so do dogs to some degree.  Another characteristic of older dogs is the loss of sight over time, and the eyes often show a milkiness over time, the older they get.

Dog Aging Compared To Humans

Figuring out the approximate age of your dog compared to you can be a bit of a sliding scale issue to figure out.  You see, all dogs start about the same, but the larger the breed, the faster the aging curve. Take a look at some of these numbers, according to Purina “Your Dog’s Age In Human Years”.  You can see in the numbers below, how a larger breed will typically have accelerated aging compared to a smaller breed.

Dog in deep concentration about dog years.
Dog Years To Human Years? What?

Dog Years To Human Years

Small Breed Dog Growth Cycle

  • 1-year-old dog = 15-year-old human
  • 5-year-old dog = 36-year-old human
  • 10-year-old dog = 56-year-old human
  • 15-year-old dog = 76-year-old human

Medium Breed Dog Growth Cycle

  • 1-year-old dog = 15-year-old human
  • 5-year-old dog = 36-year-old human
  • 10-year-old dog = 60-year-old human
  • 15-year-old dog = 83-year-old human

Large Breed Dog Growth Cycle

  • 1-year-old dog = 15-year-old human
  • 5-year-old dog = 36-year-old human
  • 10-year-old dog = 66-year-old human
  • 15-year-old dog = 93-year-old human

LEGEND: Blue = Small Breed, Red = Medium Breed, Yellow = Large Breed. Human Age is on the left and Dog Age is on the bottom.


American Kennel Club

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