Scientists seek answers to the canine aging process and lifespan
How long do dogs live? I think we can all agree that it’s not nearly long enough. Canine lifespans vary from as short as 6 to 8 years for certain giant breeds to an astounding 20-plus years for some tiny dogs. Owners of small and medium-size dogs can generally expect their companions to live 10 to 15 years.
Diet, good care and genetics all play a role in the length of a dog’s life, but two researchers at the University of Washington in Seattle are hoping to learn more about how dogs age, as well as whether the aging process can be delayed and the lifespan lengthened. The Dog Aging Project (DAP), headed by Daniel Promislow, Ph.D., and Matt Kaeberlein, Ph.D., plans to track 10,000 dogs in homes around the United States to get a sense of how genetic and environmental factors affect aging in dogs.
As dogs — and humans and other animals — age, organs and tissues break down, increasing the risk of age-related diseases such as cancer, cardiovascular disease, kidney disease, Alzheimer’s disease and more. Age is a greater risk factor for these diseases than diet, weight and exercise.
“The big picture behind what we’re trying to do is to understand the aging process so we can delay the onset and progression of all these diseases,” Dr. Kaeberlein says. “It’s sort of a fundamental shift from the traditional medical approach, which is to wait until dogs — or people — are sick, and then try to treat the disease.”
The dogs in this observational study will include many different breeds in different environments: short-lived dogs, long-lived dogs, dogs in wealthy households and dogs in more modest households. The researchers will look at not just how long the dogs live, but also at how environmental factors affect them as they age.
Included in the DAP will be a smaller study, with up to 36 pet dogs in the Seattle area. It will look at whether a drug called Rapamycin — used to prevent organ transplant rejection in humans — can slow aging, extend canine lifespans and improve quality of life. The drug has been shown to increase lifespan in many different organisms, Dr. Kaeberlein says, as well as improve cognitive, cardiac and immune function in animals such as mice.
“There’s been accumulating evidence over the past several years that not only do they live longer, but that the aging process itself is slowed down,” he says.
Of the 46 dogs whose owners have expressed interest in enrolling them in the Rapamycin study, only 26 dogs so far have met the criteria to be included: at least 6 years old, weighing at least 40 pounds and with no pre-existing conditions. Among them are golden retrievers, a greyhound, Labrador retrievers, German shepherds and mixed breeds.
In both studies, dogs are good subjects because their shorter lifespan allows scientists to see results in a decade or less.
“If we had a large enough sample size, we could know in three years — certainly in five years — the extent to which Rapamycin improved healthy aging in dogs,” Dr. Promislow says. “And for a longitudinal study of age, where we want to follow dogs throughout life and understand the genetic or environmental factors that affect aging and disease in dogs, you can do that in a decade. That’s not possible in that timeframe in people.”
The eventual results could have implications for humans, but the dog-loving scientists say their research is about more than that.
“We’re both determined to find ways to improve the quality of life for dogs,” Dr. Kaeberlein says. “This is not just about finding something that will help people. It might be good for dogs and their owners.” ¦