Ask a friend how old their pet is in human years and watch them make quick calculations in their head, multiplying the years of Fluffy or Fido's life by seven.
But experts say that those calculations don't take into account a variety of factors, from the quality of the bond between you and your pet to its weight in its early years.
So the commonly held belief that pets age seven times faster than humans isn't exactly accurate. People often wonder how old their dog or cat is “in human years” but the advice to multiply the pet’s age by seven won't work when its applied to a homebound Abyssinian and an outdoorsy Great Dane.
It’s impossible to apply a general formula like that because dogs and cats age at different rates depending on factors such as breed, size and environment. For instance, giant breeds age more rapidly than small ones, and cats that live outdoors are subject to harsher living conditions and greater stresses on their bodies than pampered indoor cats.
Find Out Your Pet's Age
A better way to compare dog and human ages is to estimate that a 1-year-old dog is equivalent to a 12-year-old person and a 2-year-old dog is equivalent to a 24-year-old person. For every year after that, add four years.
That formula takes into account the rapid maturation that occurs in the first two years of a dog’s life and then the slowing of the aging in following years, says Martha Smith, DVM, director of veterinary services at Boston’s Animal Rescue League.
How long can pets live? Max, a terrier mix owned by Janelle Derouen of New Iberia, Louisiana, has passed his 29th birthday, and Smokey, a Shih Tzu owned by Joe and Mary Slatton in St. Petersburg, Florida, is more than 26 years old.
Max and Smokey have lived well beyond the norm, but more and more pets are living longer lives. It’s not unusual for some pets nowadays to reach 15 years or more.
Size, Breed, Lifestyle Affect Longevity
One of the main factors that affects how long a dog will live is size. Small or medium-size dogs live longer than large dogs, and toy breeds tend to have the longest life spans.
Giant breeds, on the other hand, can be lucky to live six or eight years. A Great Dane, Irish Wolfhound, Newfoundland or Saint Bernard that reaches 10 or more years is ancient.
Typically, small breeds live 12 to 14 years; large breeds 10 to 13 years; and giant breeds 6 to 8 years.
Well-cared-for cats that live indoors have an even greater lifespan. It’s not unusual for them to live into their late teens and sometimes into their 20s.
Siamese and Abyssinians in particular are renowned for making the most of their nine lives.
Good genes undoubtedly play a role in pet longevity. If you’re buying a purebred puppy, ask the breeder how long her dogs usually live.
Good nutrition and careful weight management help, too. Don’t let large and giant-breed puppies pack on the pounds at a young age. It’s better for them to grow slowly and reach their genetically pre-determined size when they are 2 to 3 years old.
When growing puppies are kept slightly thin, there’s less stress on the skeleton and organs such as the heart as the dog matures. Dogs that over their lifetime remain lean and fit live an average of two years longer than dogs allowed to become overweight.
Pet gerontology experts—yes, they exist—say the reasons dogs and cats are living longer can be attributed to a stronger human-animal bond and better veterinary care and nutrition.
That’s good for our pets and ourselves: we get the pleasure of each other’s company for an extended time, even if it’s never quite long enough.