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Dogs: Ages and Stages (Part 3) - Adolescence / Adult / Senior

Is time for the third and final part of our series about the stages of a dog’s life. Today, we will talk about three stages. Adolescence, Adult, and Senior.


The period of canine adolescence goes from Sexual Maturity to what we call Social Maturity. Different individuals may reach social maturity at different ages. However, on average, social maturity in dogs is believed to be reached between two and three years of age.

At this stage the dog is sexually mature but not socially mature. The adolescent individual deals daily with continuous hormonal discharges that are finishing the formation of certain areas of the body, and this high level of hormonal discharges causes significant changes in the behavior.

It is common to see a regression in the teachings learned in the basic obedience training. Dogs behave more defiantly, and try to find their place within their group. They can become more challenging to owners, and conflicts over space, food, and toys can appear at this age. I usually call a dog at this age “a dog without a brake”. Impulsive and defiant.

Physically, muscle and bone are growing, and the dog is usually skinny. Growing upwards instead of growing sideways.

Environmental enrichment, basic obedience training, and mental enrichment are extremely important at this age.


The adult stage begins between two and a half and three years of age, and all physical and behavioral growth has already been completed.

The end of the adult stage will depend on the breed. Small breed dogs have a longer adult stage, reaching up to twelve years of age, while large breed dogs reach the next stage earlier.

On average, we can say that the adult stage ends around nine years of age.

Being the longest phase of an individual's life, it is necessary to continue maintaining the same level of mental and physical interaction with the world. Walks, trips, games, good food, and good veterinary care can further extend the adult stage of the dog.

It is common and expected that the urge to play and disposition begin to decline as adulthood extends.


The senior stage is the final stage of a dog's life. It begins after the adult stage, and its beginning depends directly on the breed of the dog.

Large breed dogs enter the senior stage earlier, between six and seven years of age. Medium breed dogs between eight and nine years old, while smaller breed dogs enter the senior stage after ten years of age, and in some cases only after twelve years of age.

Physically, the appearance of gray hair on the face, around the muzzle and eyes, are the first signs that the senior stage has arrived. This can be followed by weight loss or gain, as well as loss of muscle strength. It becomes more difficult for the dog to climb stairs, get into the car, or even jump on the owner's lap.

The opacity in the eyes also appears. And it is necessary to make an addendum because many people confuse this opacity with a cataract. Evidently, dogs can develop cataracts with age, but in general, the opacity in the eyes due to the arrival of old age happens because of the thickening of the lens, and not necessarily due to cataracts.

In the behavior, a dog entering the senior stage is usually less willing to play, sleeps more, and becomes less receptive to the owner's calls. Hearing loss can also appear.

Unfortunately, dementia is not uncommon in adult dogs. I saw that happening with one of my Border Collies after thirteen and a half years of life. He started to face walls and was lost inside the house, needing help to find his way back to his bed.

Many people don't have the patience to deal with a senior dog. What I always say is for people to try to think of all the moments of joy your friend gave you when he was young. That's the moment your friend needs you.

And with that, we finish the series about dog’s life stages. Stay tuned for more posts, and information right here.

Marco Magiolo is a bestselling author, trainer, and speaker. Connect with Marco on social media and subscribe to future newsletters and updates.

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