What’s your dog’s age in human years? New UCSD formula is far more accurate

For years, dog owners have used the rule of thumb that one dog year equals seven human years to estimate their pet’s age in human years.

[Mar. 19, 2023: Staff Writer, The Brighter Side of News]

The formula provides a new “epigenetic clock,” a method for determining the age of a cell, tissue or organism based on a readout of its epigenetics. (CREDIT: Creative Commons)

For years, dog owners have used the rule of thumb that one dog year equals seven human years to estimate their pet's age in human years. However, a new formula developed by scientists has shown that the way we have been calculating our furry friend's age is far from accurate.

The formula, developed by researchers at the University of California, San Diego, takes into account the changes in DNA methylation patterns that occur as dogs age, providing a more precise estimation of a dog's age in human years.

The study, which was published in the journal Cell Systems, analyzed the DNA methylation of 104 Labrador Retrievers aged from a few weeks old to 16 years old, allowing researchers to create a new formula that more accurately maps a dog's age to its human equivalent.

According to the formula, a one-year-old dog is equivalent to a 30-year-old human, while a four-year-old dog is equivalent to a 52-year-old human. This new formula suggests that dogs age rapidly in their first two years, with a two-year-old dog equivalent to a 42-year-old human.

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“There are a lot of anti-aging products out there these days — with wildly varying degrees of scientific support,” said senior author Trey Ideker, PhD, professor at UC San Diego School of Medicine and Moores Cancer Center. “But how do you know if a product will truly extend your life without waiting 40 years or so? What if you could instead measure your age-associated methylation patterns before, during and after the intervention to see if it’s doing anything?”

The traditional formula of one dog year equals seven human years was based on the average lifespan of a dog and a human, and not on any specific biological process. The new formula, however, is based on the changes in DNA methylation patterns, which occur as dogs age.

According to Trey Ideker, "The new system is superior to the previous 'multiply by seven' formula, which is an oversimplified rule that can lead to misconceptions about how dogs age."

Dog Age Calculator (CREDIT: UC San Diego)

The formula could have important implications for veterinary care, as it provides a more accurate way to determine a dog's age-related health risks. In addition, it could also help veterinarians determine the best time to perform certain medical procedures, such as spaying or neutering, which can have different risks and benefits depending on a dog's age.

The new formula is also important for understanding the aging process in dogs, which could have implications for research into aging in humans. As dogs age, they experience many of the same physiological changes that humans do, including changes in the immune system and an increased risk of diseases such as cancer.

By this time, dog aging has slowed down, so an 8-year-old dog is like a 64-year-old human.

The New Formula

The equation: 16 ln(dog age) + 31 = human age.

For iPhone calculators that have the natural logarithm, or "ln," function, first type in the dog's age. Then hit the "ln" button. Multiply that result by 16; then add 31.

If you're using Google’s scientific calculator: First, hit "ln," then type in the dog’s age, then equal it out. Next, multiply by 16, and then add 31.

Using that equation:

  • a 1-year-old dog is like a 31-year-old human;

  • a 3-year-old dog is like a 49-year-old human;

  • a 7-year-old dog is like a 62-year-old human.

Using the formula, a new "epigenetic clock" can be used to determine a cell's, tissue's or organism's age based on a reading of its epigenetics — chemical modifications like methylation that alter the genes' status without altering their inherited genetic sequences.

Ideker and others have previously published epigenetic clocks for humans, but they are limited in that they may only be accurate for the specific individuals on whom the formulas were developed. They don’t translate to other species, perhaps not even to other people.

Researchers will next test other dog breeds, analyze saliva samples to see if the results hold up, and test mouse models to see what happens to their epigenetic markers when you prolong their lives.

The researchers hope that the new formula will be widely adopted by veterinarians and dog owners alike, providing a more accurate and informed approach to understanding a dog's age and related health risks.

The formula has been met with enthusiasm by dog owners and veterinarians alike, with many praising its accuracy and potential implications for canine health. However, some have noted that the formula may not apply to all dog breeds, as different breeds have different lifespans and may age differently.

Despite this, the formula represents an important step forward in our understanding of canine aging and health, and provides a more accurate and informed approach to estimating a dog's age in human years.

For more science and technology news stories check out our New Innovations section at The Brighter Side of News.

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Joseph Shavit
Joseph ShavitSpace, Technology and Medical News Writer
Joseph Shavit is the head science news writer with a passion for communicating complex scientific discoveries to a broad audience. With a strong background in both science, business, product management, media leadership and entrepreneurship, Joseph possesses the unique ability to bridge the gap between business and technology, making intricate scientific concepts accessible and engaging to readers of all backgrounds.