It’s a simple equation that anyone with a dog knows, one human year equals seven dog years. But like many things in life – opening foil topped drinks on planes and why children like to eat dirt – it’s not so simple. Figuring out how to work out your dog’s age is a lot more complicated, and it often depends on what breed you have and more importantly what size they are.
“You can’t really kill the seven-year rule,” Kelly M. Cassidy, a curator of the Charles R. Connor Museum at Washington State University, who compiles studies about longevity in dogs told the American Kennel Club.
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The first myth to bust is that dogs age at steady rate. In fact, dogs mature very quickly for the first two years, unlike human babies, who are still relatively helpless at two. Two-year-old humans are entertaining, but can they feed themselves, sleep outside and hunt with you? Well, technically yes, at least in the short term, but the authorities may become involved further down the track.
According to the kennel club, 15 human years equals the first year of most dogs. This makes sense, because most one-year-old dogs are generally fully grown but still act like a puppy, which sounds like most 15-year-old humans.
After that, the next year is equivalent to human nine years. Their ageing remains steady at four years per human years. That is until about age six years, when little dogs age much slower than their larger counterparts.
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Why do little dogs age slower than big dogs?
Little dogs age about four dog years per human years, where larger dogs age about five or six years per human year.
This is why a larger breed – about 22kg or larger – is considered a ‘senior’ dog at about five to six years. Smaller dogs – about 9kg – and cats are considered senior at seven years.
Generally, in mammals, the bigger you are the longer you last. Whales live longer than mice. But dog ageing turns this on its head and no-one is quite sure why. There are a few plausible explanations, such as their accelerated growth makes them more prone to abnormal cell growth and cancer and stress on the body. But a definitive answer still eludes researchers.
Anyway, if you want a long-lasting dog, buy a Chihuahua, not a Great Dane.
The good news is that as we love our dogs, plenty of money is being directed into researching their longevity so we can keep them with us for longer.
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What if you’ve ‘rescued’ a dog?
If you are not sure of your adopted dog’s age and want to find out there are a few clues:
- at eight weeks old all the baby teeth are in
- seven months all the permanent teeth are in and are white and clean
- one to two years, teeth are duller and may have tartar build-up
- three to five years, all teeth may have tartar build-up and some tooth wear,
- five to 10 years, teeth show more wear and tear and signs of disease
- 10 to 15 years, teeth are worn and there can be heavy build-up of tartar. Some teeth may be missing.
Your vet should also be able to help with a complete physical examination.
And it’s worth noting, the oldest recorded dog was a blue heeler named Bluey who lived in Rochester, Victoria, who lived to 29 years and five months.
The current world’s oldest dog is TobyKeith, a 21-year-old Chihuahua living in Florida. He takes the title from Pebbles, a 22-year-old toy fox terrier from South Carolina. She died on 3 October after a life of “country music and being loved”, according to her owner’s Instagram post.
How long did your favourite dog live? Would you buy a dog based on how long the breed is predicted to live? Why not share your opinion in the comments section below?
