Why Do Dogs Age So Fast?

By John Martin - July 6, 2020

old tired dog resting on the floorBreed, lifestyle and health. All things considered, most dogs live for about 10 to 20 years.

They grow old a lot faster than human beings. A dog year is commonly calculated as seven years for every human year.

This means, if you have had a happy and healthy dog for about 10 years, your dog’s age is believed to be 70 human years. But what if we told you all of that is ancient history?

What Does ‘Age’ Mean in Animals?

Usually, when we talk about age, we mean the time that has passed since birth. But is it the same thing in animals too?

The question arises from the human-dog age mathematics which throws some unbelievable facts.

For example, some dogs live for as long as 20 years. That is an unfathomable 140 human years.

Does that make sense? Not quite, right?

In animals, age is more subjective. It is assessed based on physiological factors like activity levels, disease status, cognitive impairment, etc.

Academically, this is called the frailty index and is measured in relation to the deficits of the organism. It is defined as the ratio of deficits in the organism to the total number of deficits considered.

Apart from that, there are other indicators like the proteins produced by different genes at various stages of life, the number of immune cells and ageing biomarkers. Sometimes, mental health and lifestyle factors are also considered because they heavily influence the rate at which ageing takes place.

Meaning that if you’re a chain smoker or a chronic alcoholic, you might be 50 years old but you probably have the body of a 40 year old. So experts believe that when it comes to dogs, it is far more sensible to go by biological markers rather than counting the number of years they have been alive.

They believe that one of the ways to calculate age in that sense is to check what is called the epigenetic clock. This looks at changes to the DNA of all mammals that happens over time.

In humans, these markers are also believed to be the key to figuring out the question of anti-ageing.

Is It True That 1 Human Year = 7 Dog Years?

This one might be a heartbreaker if you love math and science. That every dog year is equal to seven human years is more like folklore at this point.

The fact is that dogs age rapidly in the first part of their lives and slow down a little later. It is a case that somewhat resembles a time stretch and a squeeze.

They mature quite quickly during their initial years and the rest of their life is like a stretching of the middle age period. Based on this understanding, scientists have figured out a new way to calculate the age of a dog with respect to human years.

The mathematical formula is:

human age = 16 x ln(dog’s chronological age) + 31.

And if you are not a mathematical brainiac, here’s how you can calculate the age of your dog.

The first dog year is equal to 31 human years. After that, whenever the dog’s age doubles, the human years increase by 11 years.

Year one = 31 human years.

Year four = 53 human years (1→2 and 2→4 count as two doubles).

Year eight = 64 human years (1→2, 2→4 and 4→8 count as three doubles)

So four years is 31 years plus two doubles.

Year four = 31 + 2×11 = 53 years.

And eight years is 31 years plus three doubles.

Year eight = 31 + 3×11 = 64 years.

So your 10-year-old dog is actually 86 years old and not a frail septuagenarian pushing 70. The only real takeaway for dog owners from all of this calculation is that your dog is moving into middle age a lot sooner than you might think.

This also means that they might be a lot older than you think they are.

Can This Be Applied to Humans?

Going by that logic, you might wonder if there are things about ageing in human beings that have nothing to do with the number of candles on our birthday cake. You are not entirely wrong.

Adding certain methyl groups to specific DNA sequences is how scientists track the biological (not chronological) age of humans. Our lifestyles, genetics and the damage that diseases do to our bodies are all taken into account for this calculation.

It is also used to calculate life expectancy in human beings and is something that greatly worries ethicists because of how that data can be misused by the likes of insurance companies.

How Does Ageing Work in Dogs?

Obviously, dogs age a lot faster than human beings no matter how you calculate their age. Irrespective of their breed, all dogs have the same basic growth pattern.

They hit puberty around 10 months and die before they are 20 years old. This is because their bodies work a lot harder than human beings.

This is true even though their environment is the same as humans and healthcare, at least for pets, is designed the same way it is for their humans. They have a different genetic make-up and they have a higher metabolism than human beings.

But another thing to remember if you have a large dog (which you are probably trying to forget) is that their baseline mortality rate is higher. Which means that their life expectancy is shorter than smaller dogs.

Scientists are still trying to explain why, for example, a Great Dane lives only for seven years while a toy poodle lives for 14. The only clue they have is that the concentration of growth hormone IGF-1 is lower in smaller dogs.

This is not to say that heartbreak is any less for people who have smaller dogs.

And if you haven’t already, try to listen to their heartbeat. It is a lot faster than the heartbeat of human beings.

So, naturally, they also tend to get tired sooner than we do.

They need a good amount of exercise, proper nutrition and a lifestyle that promotes happiness and good mental health.