Their muzzles may be grizzled and their teeth worn, but old dogs lead the way when it comes to unraveling the secrets of long life. As with their extra-old human counterparts, the question arises: What has enabled them to dodge cancer and other common or crippling diseases?
Both dogs and people are living longer these days—a well-reported trend. Still, not all dogs make it to their 13th year. That’s the “lucky number” for Rotts, according to researcher Dr. David J. Waters, director of the Center for Exceptional Longevity Studies at Gerald P. Murphy Cancer Foundation at the Purdue Research Center, who pursues his work by keeping tabs on America’s oldest Rottweilers. To qualify for a slot in the foundation’s Exceptional Longevity Database—which includes more than 140 cancer-defying Rottweilers —each dog must be at least the equivalent of a 100-year-old human. That is, 13 in dog years, an age few Rottweilers attain.
In March 2010, Waters set out to meet the database’s surviving 15 hardy seniors on a 23-day, cross-country trip dubbed the “Old Grey Muzzle Tour.” These dogs had lived 30 percent longer than expected for a breed whose lifespan averages 9.4 years.
The Murphy Foundation, which focuses on “basic, comparative and clinical research at the crossroads of cancer and aging,” is home to the Center for Exceptional Longevity Studies (gpmcf. org/celsmainpg.html), the first systematic investigation of extreme longevity in pet dogs. The Exceptional Longevity Database was established in 2005. “At that time, we had information on fewer than 25 Rotts who lived at least 13 years,” Waters says. “Now, we have collected life history data and medical records from almost 200 of these ‘centenarian Rottweilers’ from across the U.S. and Canada.”
Working with these senior Rottweilers has allowed Waters to observe their lifestyles and environments and interview owners, who filled out questionnaires about their dogs’ background and medical history, parents’ lifespans, diet—including supplement usage—and more. With each dog, Waters performed an exam and collected DNA samples.
Since the completion of the Old Grey Muzzle Tour, Waters has visited 11 additional long-lived Rotts in their homes, making detailed observations and swapping stories with owners. “You’ve heard of the Dog Whisperer. I guess you could call me the Dog Visitor,” Waters says. “At each stop, I’m searching for a special kind of information, finding the differences that make a difference in how we think about the process of successful aging.”
These individual dogs interest Waters, but it’s no small task sorting out what makes them unique, which takes the work into the realm of epigenetics, an emerging field that is contributing to our understanding of the heredity and environment puzzle. Beyond both nature and nurture, epigenetics is “the study of changes in gene activity that do not involve alterations to the genetic code but still get passed down at least one successive generation,” according to John Cloud in his article, “Why Your DNA Isn’t Your Destiny” (Time, Jan. 2010). “It is through epigenetic marks that environmental factors like diet, stress and prenatal nutrition can make an imprint on genes that is passed from one generation to the next,” writes Cloud.
Waters is optimistic about the future of canine studies, saying they hope to expand their work to other breeds. “We have established BAM—the Biorepository at Murphy—the world’s first biorepository of DNA, serum, blood cells and autopsy tissues from exceptionally long-lived dogs,” he says. “Now that we have these biological specimens and medical data in hand, we are gearing up to probe the underpinnings of successful aging.”
For years, cancer studies have Been carried out on rodents. But when it came to human clinical trials, the research often didn’t translate well. With the sequencing of the canine genome in 2005, researchers realized that dogs are genetically more similar to people than rodents are, making dogs better models for studying the ways tumors develop. Working with dogs also allows scientists to gather data about cancer progression in a much shorter time.