How Old Is My Dog In Human Years?

We’ve all heard the saying: “multiply your dog’s age by seven to get the human age.” Like most simple rules, there’s a lot wrong with that:

  • Dogs age at different rates to people depending on how old they are. They age much faster when young and slower when old.
  • The number ‘seven’ has been chosen to match our lifespan to an arbitrary dog age of eleven. No vet would consider 11 an accurate dog lifespan any more.

Here is a more modern and less simplistic view:

Dog YearsHuman Years
115
223
328
433
538
643
748
853
957
1061
1165
1269
1373
1477
1581
1685
1789
1893
1997
20101

after this add 3 human years for each dog year. This approach is an amalgamation of several modern theories first proposed by Lebeau (1953). The Wikipedia page on dog ageing gives a good summary.

The two methods only agree around middle age, as you can see by the graph.dog age lifespan

Even if more accurate, the new approach brings up two questions:

Do Large Dogs Age Faster?

Everyone says it, but what is the evidence? There isn’t much. All people are doing is observing that certain large breeds have shorter lifespans. That’s not the same thing.

Visit this page for the best data we have on how long individual dog breeds live. Is it correct that the larger breeds are known for shorter lives? I want to show you some good news from our clinic that changes what we think.

dog lifespan data

Dogs less than 10kg and over 20kg at Walkerville Vet. Ages are shown as a percentage of the total for that group.

Look at this recent data from our clinic on 800 living patients. If you can see any difference between large and small dog lifespans you’re doing better than me. Read why I think old dogs now live longer than they used to.

The dog breeds famous for short lifespans are the giant breeds like Great Danes and Wolfhounds. I think that the diseases they are known for (bone cancer and dilated cardiomyopathy) take them while they are still in the prime of life. If we look at the large breeds, like Golden Retrievers for example, it’s not at all clear that they live any shorter lives than small dogs.

When Is A Dog Considered Old?

Airedale terrier beachBritish is an Airedale terrier who inspired this blog. By the old method, he’s 63 years old and even the new way says he’s 57. Most importantly, in his head, he’ll always be a teenager.

Dogs are only as old as they feel. I don’t think we should talk about ‘old age’ in dogs the way we do about people being retired or pensioners. True, knowing the equivalent human age is helpful in thinking about healthcare but it says nothing about their state of mind.

When I wrote about how to know when to go to the vet I said all change is meaningful. Old age is just the sum total of separate diseases. If we keep them under control our dogs can feel and act young right up to their senior years.

Next week: How to help your dog live longer.

Lebeau, A. (1953). L’âge du chien et celui de l’homme. Essai de statistique sur la mortalité canine. Bulletin de l’Academie Veterinaire de France, 26, 229-232. The matching of human and dog ages in this visionary study from 1953 has stood the test of time and become the basis for modern approaches to assessing dog age.

Have something to add? Comments are welcome and will appear within 24 hours of lodging.

By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These blogs are from a series regularly posted on Facebook, Tumblr, Twitter, Google+ and Pinterest. Like or follow our page or subscribe via email to read the latest.

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