A golden retriever in Tennessee just became the oldest of its breed known to date, after turning 20 this April, according to news reports.
August or "Augie" who was adopted when she was 14 from the Golden Retriever Rescue of Southern Nevada after being rehomed twice, is still surprisingly healthy, one of her owners Jennifer Hetterscheidt told Golden Hearts, a blog about golden retrievers. Augie is a bit shaky when she wakes up, but enjoys her daily walks around the yard, she said.
Most dogs live between 8 and 15 years, but there are accounts of some dogs, generally smaller breeds, that live for more than 20 years. The oldest dog known was an Australian cattle-dog named Bluey who was put to sleep at age 29 on Nov. 14, 1939, according to The Guinness World Records. Golden retrievers typically live between 10 and 12 years, but there have been some records of them living to 17, 18 or 19, according to Golden Hearts.
But why do our furry friends have relatively short lives compared with humans?
"We don't know," said Trey Ideker, a professor of genetics at the University of California, San Diego. But Ideker said he's not surprised that Augie lived to age 20. Dog life spans will "undoubtedly" improve over time and already have, he said, similar to how human life spans have improved since we stopped sculpting rocks into tools and began erecting hospitals.
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Domesticated animals typically live longer than wild animals because they face fewer threats, such as from predators, Ideker told Live Science. What's more, domesticated animals are treated for diseases, which can increase their lifespan. But there's still much mystery around why sharks can live hundreds of years, while humans rarely surpass 100, and mice live for only about 2 years, he said.
Some researchers have suggested that the bigger the animal, the lower its metabolic rate — the rate of energy expended by the body — and the longer it lives. This idea holds that animals with faster metabolic rates run out of "petrol" sooner than their "slower" counterparts, Susan Hazel, a senior lecturer at the School of Animal and Veterinary Science at the University of Adelaide wrote for The Conversation in 2018.
But this explanation doesn't work for some animals such as relatively wee-sized parrots that have high metabolic rates but can live for more than 80 years. This hypothesis also breaks down with dogs, as small dogs are known to live longer than bigger dogs, she wrote.
The key may be hidden in doggie (and human) DNA. A natural process called DNA methylation — or the attachment of a group of three hydrogens and one carbon (a methyl group) onto parts of a DNA molecule — can serve as a sign of aging as the rate of methylation tends to increase with age. Scientists use these "epigenetic clocks" within the DNA to discern a person's age, according to a previous Live Science report.
These clocks have "shown not to really translate to other species," Ideker said. But it turns out, researchers "were just looking at the wrong marks." Ideker and his team found a set of "conserved clocks" among dogs, humans and mice that allowed them to compare the species. They published their findings Nov. 19, 2019, in the preprint journal bioRxiv (an updated, peer-reviewed version will be published in early July in the journal Cell Systems).
But the question remains: Is this methylation a cause or an effect of aging? Or perhaps it's linked to aging in some other way. "No one knows, it's all speculation," Ideker said. But if we can figure out why methylation happens — and why it happens faster in some animals than others — perhaps that can help humans control or slow aging, he said. And then the furry loves of our lives can live longer (Oh … and us too).
Augie's owners, Jennifer and Steve Hetterscheidt had planned a 100-person party for Augie's 20th birthday that had to be canceled because of the pandemic, according to CNN. Still, she got decorations, a carrot cake and all of her favorite food, including blueberries, bread and pasta, Jennifer Hetterscheidt told CNN.
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Originally published on Live Science.