Biotech startup predicts age of dogs in hunt for clues about human aging

How it works: Organisms have a chronological age and a biological age. The latter accounts for an individual's habits, behaviors, disease and other factors affecting the body's health and functioning over time.

• Individuals — human, canine or otherwise — age at different rates, and the effects of aging seen in tissues and cells can appear at different times in individuals of the same chronological age.
• Scientists are searching for molecular markers to measure biological age across animals.

What's happening: One marker of intense interest: A chemical modification that changes the structure — but not the sequence — of DNA as an individual ages.

• It involves the addition of methyl groups — a molecule made up of one carbon and three hydrogen atoms — to specific sites on DNA, turning genes on and off.
• These methylation patterns, which change over time and are affected by an individual's behavior or environment, have been used to predict chronological age in a range of species, and are being studied as indicators for biological age.

Driving the news: San Francisco veterinary medicine startup Loyal is reporting results from its X-Thousand Dogs study that looked at DNA methylation in about 1,600 dogs from 48 U.S. states, which the company shared first with Axios.

• The canine cohort incudes 187 different breeds — mixed, pure and designer — with ages ranging from puppies to 12 years old.
• Participants provided a saliva sample from and health information about their dog, including their feeding routine and energy level.

What they found: The Loyal researchers measured levels of methylation across the samples and found a correlation between dogs' reported chronological ages, predicted ages and DNA methylation patterns, says Erica Andrews, a researcher at Loyal.

• The reported results are consistent with previous findings in other aging and methylation studies.
• The company says a dog's estimated methylation age can be predicted with an error of about six months.
• Study participants are receiving information about their dog's methylation age in personalized reports from Loyal.
• Accurate estimates of a dog's age — especially those that were adopted with an unknown age — could help owners care for their companions, the company says. "By knowing a dog's age you can provide ideal care for that stage of life and be aware of age related changes that may occur," per the reports.

But, but, but... The study isn't designed to diagnose diseases — it is providing a broad indication of age, Andrews says.

• Methylation may be just one facet of biological aging.
• Open questions remain about the link between methylation and aging, including whether DNA methylation changes are caused directly by aging or other age-related factors.

What they're saying: When Abigail Marshall adopted her dog Mazel in 2010, she was told he was 11 months old.

• But the Loyal study estimates his methylation age is nine months younger. (That doesn't necessarily mean his birthday was nine months later.)
• "It is very good news because I am very attached to him," Marshall says of the small, fuzzy white dog that is a mix of unknown breeds (she suspects Jack Russell and Maltese).
• "He’s in pretty good shape," she adds. "But he is older so he gets days where he is very creaky and arthritic, and days where he has the energy of a puppy. I understand what it's like. I’m 68 years old and I have my creaky days."

The big picture: Loyal and other groups, including the Dog Aging Project and Vaika project, are trying to develop drugs to delay aging in dogs and increase their lifespan.

• Dogs, which have similar lifestyles and aging trajectories as their owners, share some age markers with humans, according to research published earlier this year.
• Ultimately, researchers hope to leverage similarities between dogs and people to create drugs that delay aging in humans.
• The goal is for these drugs to target the underlying ways "a complex organism ages to treat diseases that today are considered completely disparate," Loyal founder and CEO Celine Halioua says, citing cancer and osteoarthritis.

Go deeper: Epigenetic ‘clocks’ predict animals’ true biological age (Quanta)