How old is your dog?

Chihuahuas - Eric, Chester and Alfie

There’s a new way to calculate your dog’s age!

We were brought up to believe that a year of a dog’s life was the equivalent to seven human years, but it didn’t always ring true when we watched the development of puppies, young dogs and adults.

Photo showing seven Border Collie dogs, which make up four generations of the same family
Four Generations! Puppy Martin (centre) with his parents Nell and Remus behind him. Remus’s parents Kay (l) and Big Ezra are at the front. Ezra’s mum Mel, is behind him, while his dad Eli, is to our left of Martin.

With Border collies we expect adolescence to kick in at any time after 6 months, and it can last up to 14 months or so. But adolescence in humans doesn’t (typically) start at the age of three and a half and certainly isn’t over by the age of ten.

As you might expect, the “1 dog year equals 7 human years” formula is a crude simplification. It was originally calculated by dividing human life expectancy of around 77, by a dog’s typical life expectancy of around 11.

Chihuahua-Papillon cross
Chihuahua-Papillon cross – this is Chester

Of course, this doesn’t take into account the different life expectancies of the various breeds, which can vary enormously. Using the old formula I’m living with 91 and 98 year old Chihuahuas. I can only hope to have half their zest for life when I’m tottering towards my first century, but small dogs age more slowly than their more cumbersomely-built cousins.

The authors of a new study into ageing have come up with an equation that better represents the life stage that our dog has reached.

Be warned, you need a scientific calculator: Human equivalent age = 16 x ln (dog’s chronological age) + 31.

Which means, enter your dog’s age in years into your calculator and click ln (which, I believe, means natural logarithm). Multiply the result by 16 and then add 31.

Suddenly my Chihuahua companions are 73 and 72. Science has taken years off them.




Watch Pearl Glen, Mel and lots of the dogs you saw in our first DVD Border Collie Sheepdogs – Off Duty! PLUS MANY MORE! The DVD is available from our DVD Store – and we automatically ship the correct format for your country. More info.


Leave a Reply

Your email address will not be published. Required fields are marked *