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Life in dog years: Many pets living longer

Veterinarians say it’s not unusual for some dogs and cats to reach 15 years or more, and they’re seeing more and more pets do so.
Image: Chanel, formerly the world's oldest dog
Chanel, a wirehaired dachshund who was recognized as the world’s oldest dog, died on Aug. 28, 2009. She was 21 years old — roughly equivalent to 120 in human years, according to Chanel’s veterinarian.Karl And Denise Shaughnessy / AP file
/ Source: contributor

When Denice Shaughnessy’s wirehaired dachshund Chanel died last month at the age of 21, she was heralded as the world’s oldest dog, according to Guinness World Records.

Now another old dog, one still living, is vying for that title. Max, a terrier mix, is 26 years old, according to his owner, Janelle Derouen of New Iberia, La., although Guinness has yet to certify his status.

And dogs aren’t the only pets living longer. A Sphynx cat, Granpa Rexs Allen of Austin, Texas, was 34 years old when he finally died in 1998.

Dogs like Chanel and Max and cats like Granpa Rexs Allen are outside the norm, but they may be trailing indicators of an increasingly long pet lifespan. Veterinarians say it’s not unusual for some dogs and cats to reach 15 years or more, and they’re seeing more and more pets do so.

“Just as the average life expectancy for people keeps reaching closer to the century mark, we’ll continue to see the same parallels in our pet population,” says Martha Smith, director of veterinary services at Boston’s Animal Rescue League.

The choices we make for our pets can go a long way in affecting their lifespans, say veterinarians. And so can the pet you pick.

Size matters
If you want your dog to live a long time, choose a small or medium-size breed. Longevity directly correlates to breed size. Large dogs have shorter lifespans than small or medium-size dogs, and toy breeds tend to have the longest lives of all. As for giant breeds such as Newfoundlands, Saint Bernards, Great Danes and Irish wolfhounds? Well, they don’t have a giant-size lifespan.

“The most short-lived breeds are giant breeds. They tend to live to be 6 or 8 years old,” says John Berg, a veterinarian and professor in the department of clinical sciences at Tufts Cummings School of Veterinary Medicine in Grafton, Mass. “Large breeds like shepherds, Labs, goldens probably live 10 to 13 years and the medium and small breeds 12 to 14 years. Mixed breeds in general tend to live a little bit longer than pure breeds.”

It used to be commonly thought that to calculate a dog’s age in human years, you simply multiplied by seven. But you can’t apply that formula to any single dog breed because of the variability in aging between breeds. You can make a pretty good guess, though, many vets say, by figuring that a one-year-old dog is equivalent to a 12-year-old person and a two-year-old dog is equivalent to a 24-year-old person. For every year after that, add four years.

“That formula is probably the most accurate because it does take into account the maturation that happens in the beginning of the dog’s life and then the slowing of the aging in subsequent years,” Smith says.

Cats live a long time, too. It’s not unusual for veterinarians at Tufts to see cats that are 20, Berg says. Breeds such as Siamese and Abyssinians seem to have an edge when it comes to really stretching out that ninth life, but any well-cared-for cat that lives indoors is likely to reach the upper teens and maybe even into the early 20s.

Select for longevity
Pat Santi, who breeds Cardigan Welsh Corgis in Coatesville, Pa., and currently has 32 of the short-legged herding dogs, says her dogs often live to be 18 or 19 years old. The average lifespan for the breed is 12 to 14 years.

Does Santi simply have the magic touch? Not necessarily. She attributes her dogs’ longevity to good genes and good nutrition.

Genetics is undoubtedly a part of the equation.

“To a significant degree, how long an individual dog or cat is likely to live is pre-programmed, just like it no doubt is for people,” Berg says.

With that in mind, some dog breeders are selecting for longevity. The Doberman Pinscher Club of America instituted a longevity program in 1997 to identify and track dogs that reach the age of 10 or more or whose parents reach that age.

“When I started practice a lot of years ago, if I saw a Doberman come in and it was 6 to 9 years old, I might think ‘Well, it won’t be here next year,’ ” says Johnny Hoskins, a veterinarian, internal medicine consultant and pet aging expert in Choudrant, La. “I’m seeing now 14-, 15-, 16-year-old Dobermans.”

If you’re buying a purebred puppy of any size, ask the breeder how long her dogs usually live.

Even some giant breeds are living longer.

“If they don’t have heart problems, it’s possible for the giant breeds to get up to 10, 12, 14 years of age,” Hoskins says.

Don’t super-size me
That’s because breeders and veterinarians now know that large- and giant-breed puppies should be slow to grow. Instead of high-protein puppy food and calcium and phosphorus supplements for bone growth, they advise new owners to start puppies on foods made for growing big dogs or adult dogs, both of which contain lower amounts of protein and mineral supplements than traditional puppy diets. Keeping pups slightly thin and giving them a full two to three years to reach their mature size puts less stress on the skeleton and organs such as the heart.

Studies have shown that slightly underweight dogs live an average of two years longer than overweight dogs.

“These dogs were basically underfed a little bit their whole lives,” Smith says. “They had a lifespan that was considerably longer. I think on average it was two years longer than their heavier counterparts, so staying lean, staying fit, is obviously very important in longevity.”

Pet gerontology expert and veterinarian Richard T. Goldston, in St. Petersburg, Fla., says the improvement is a combination of more responsible pet ownership, a stronger human-animal bond and better veterinary care and pet nutrition.

“If we take 100 dogs, we’re getting a whole lot more of that 100 up into the higher age groups,” he says. “Forty years ago, maybe 30 percent of 60-pound dogs would reach 11 years of age. Now, 60-pound dogs, at least 50 percent are going to live 11 years or a little bit longer.”

Goldston doesn’t see a lot of dogs reach 18 years, but quite a few reach 15, 16 and 17 years. Hoskins, who co-authored “Geriatrics and Gerontology of the Dog and Cat” with Goldston, says we probably are seeing animals live equivalently as long as humans.

“I saw in the AARP magazine that in humans now there are over 100,000 centenarians,” he says. “If we did the same type of numbers, if one could get those, I think we would have about the same percentage of animals that are up there toward 20.”