Getting a better understanding of the aging process in dogs

Sophie Cobb, a Shetland sheepdog in Omaha, recently celebrated her 20th birthday. That's an unusually long life for a dog. Most dogs are more likely to live a measly 10 to 12 years, with some making it to 14, 15 or older.

A good diet, exercise and regular veterinary care help set dogs up for a long, healthy life. But are there other ways to extend a dog's life span and improve quality of life?

Scientists with the Dog Aging Project (DAP) are seeking answers to those questions through a long-term study of how dogs age and the genetic and environmental factors that affect aging and disease in dogs.

In the process, they also hope to learn about the biology of aging in humans, because dogs share our lives — from the air we breathe to the food we eat and sometimes to the beds we sleep in.

"Dogs get the same diseases we do," said Matt Kaeberlein, one of the co-directors of the project. "The health care system in dogs is second only to our own in sophistication. What we learn about how genes and the environment shape the risk of age-related disease in dogs is likely to be related to the genes and environmental risk factors for age-related diseases in humans, as well."

More than 10,000 dogs will participate in the longitudinal study: big dogs, small dogs, mixed breeds, purebreds — all are important in teasing out the secrets behind canine aging.

Because of the compressed nature of the dog life span, a lot can be learned in a decade, both environmentally and at the molecular level.

"The dog provides us with a really terrific opportunity to ask how those molecular changes differ between long-lived and short-lived individuals within the same species," said Daniel Promislow, co-director of the project.

"They provide us with a kind of magnifier of diversity that we don't have in humans, where we don't know who's going to be long-lived and who's going to be short-lived."

While a pill to increase canine life span is still in the future, the concept isn't out of the question.

Owners can nominate middle-aged dogs to participate in a parallel five-year study (limited to 500 dogs) of a drug called rapamycin. In lab studies as well as some human studies, it appears to slow aging or improve healthy aging, Promislow says.

Cardiologists at veterinary teaching hospitals will follow the dogs' heart health over time in the double-blind, placebo-controlled study. As part of this trial, researchers will also be looking at such things as kidney function, cancer, activity levels and cognition.

Why middle-aged dogs? They are at the age where they are starting to develop age-related diseases. By starting with dogs in that period of life, researchers will be able to quickly detect whether the drug slows aging and improves heart function.

"If we had a large enough sample size, we could know in three years — certainly in five years — the extent to which rapamycin did improve healthy aging in dogs," Promislow said. "That's something that's just not possible in that time frame in people."

A 20 to 30% increase in life span in dogs isn't out of the realm of possibility, Kaeberlein said. A dog that might normally live 10 years might live an extra two years. Smaller dogs with a normal life span of up to 18 years could see an extra three or four years of life.

Studying how dogs age has more than academic interest. There's intrinsic value in improving quality of life for dogs, but making their lives longer and better improves our own quality of life, as well.