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The Science of Dog DNA Methylation and Age


Three Golden Retriever dogs at different ages pictured on a teal background.

The Embark Dog Age Test uses a dog’s DNA to measure their chronological (or calendar) age. Specifically, we use a feature of DNA called methylation. Here, we explore the science behind DNA methylation and age, and explain how we can use methylation to calculate a dog’s age with remarkable accuracy.

DNA allows us to measure dog age

There are several physical clues that veterinarians use to estimate dog age, including body shape and lens clarity. Teeth can also indicate a dog’s age, although not all dogs follow the same progression from puppy teeth to adult teeth, and age is harder to determine after puppyhood.

Even trained experts sometimes get age identification wrong when judging by visual cues alone. That’s why we use the scientific field of epigenetics to measure your dog’s age accurately, based on their DNA.

“Studies have shown age determination based on physical exam findings in adult dogs (including eye clarity, dental tartar, and tooth wear) does not yield a highly accurate result, despite pet care professionals’ best efforts with available parameters. DNA methylation offers a new method for estimating age that is much more precise. Additionally, this exciting technology may help pave the way for future discovery in dogs.”

— Jenna Dockweiler, MS, DVM, DACT, CCRT, CVAT, Veterinary Geneticist at Embark

Genetics vs. epigenetics

If you’ve used a dog DNA test, you’re probably familiar with genetics—the study of DNA. Epigenetics is a related field that looks at factors that interact with DNA.

According to the Centers for Disease Control and Prevention

“Epigenetics is the study of how your behaviors and environment can cause changes that affect the way your genes work. Unlike genetic changes, epigenetic changes are reversible and do not change your DNA sequence, but they can change how your body reads a DNA sequence.”

Epigenetic marks influence how the genes coded in the DNA are expressed. From early on in development, they tell the cells in our bodies what type of cell to become. Epigenetics can change with environment, lifestyle, stress, disease, or age.

There are many kinds of epigenetic marks that can affect DNA. Today, we’ll take a closer look at methylation, the epigenetic modification that tells us about a dog’s age. 

What is DNA methylation?

DNA methylation is one type of epigenetic modification. It doesn’t change the DNA, but it can affect which genes are turned on and off, and when. 

Methylation refers to a methyl group (one carbon atom and three hydrogen atoms, or CH3) that can be attached to a DNA strand. Our DNA is made up of four letters—A, C, T, and G. Most methylation occurs on letter C, although A can also be methylated. (Learn more about these four letters and how DNA works.)

In the diagram below, the yellow marks are methyl groups that attach to the sides of the DNA strand. These methylation sites are not permanently attached. They can be added or removed over time.

Teal background with white lines representing a DNA strand, with yellow marks representing methylation on the sides of the DNA.

Methylation is a normal process that happens in your cells (and your dog’s cells). It acts as a stop sign, telling genes when to turn on and when to turn off. Even though these methyl groups are tiny molecules, they physically block proteins from accessing the DNA. If there is a high level of methylation, then it becomes harder for proteins to “read” the DNA, so that gene is turned “off.” If the methylation is removed, the DNA becomes open and accessible, so that gene can turn back “on” again.

To learn more about epigenetics and DNA methylation, watch this video: 

DNA methylation predicts a dog’s age

Research on epigenetics and aging has been ongoing for decades. In the past 10 years, scientists have been able to use DNA methylation to estimate age. There are published papers showing this method works in dogs, humans, and many mammals.

DNA methylation is one of the most well understood epigenetic mechanisms that regulates gene expression in a cell (Arneson et al. 2022). Methylation doesn’t change the actual genetic code, but it changes how that code is expressed.

Methylation acts as a clock. As we age, the level of DNA methylation changes in a predictable way. Overall, the genome gets less methylated with age, although there are some sites where methylation increases (Field 2018; Horvath 2013). We can use the amount and position of DNA methylation to pinpoint just how old your dog is (Horvath et al. 2021).

How Embark uses DNA methylation to calculate dog age

The Embark Dog Age Test is not a genetic test; it’s an epigenetic test. Instead of looking at the genetic code (which our Breed ID Kit, Breed + Health Kit, and Purebred Kit do), the Age Test measures the amount of methylation in your dog’s DNA and translates it to their calendar age.

While the Age Test uses the same kind of microarray technology as the other Embark dog DNA tests, it involves a special processing step during DNA extraction. That extra step means that we can’t use the same DNA across both our Breed + Health Kit and the Age Test. Each test is run separately and requires its own swab.

“We were determined to create an Age Test that would work on any dog, no matter their background, breed, or size. That’s why we collected information on DNA methylation across the genome for a comprehensive panel of dogs, then trained a rigorous statistical model to convert all that information to age. I used this test on my own rescue dog, Saki, and knowing Saki’s age is helping us work with our vet to improve her care as she ages.”

—Erin Wissink, PhD, Research Scientist II at Embark

How does the Embark Age Test work?

We designed an algorithm that focuses on the methylation patterns that are very strongly correlated with actual age. To develop our accurate algorithm, we chose 500+ dogs with known ages. These dogs represent:

  • 100+ breeds
  • 200+ mixed-breed dogs
  • Toy, small, medium, large, and giant dogs

A chart showing dogs ranging in age from 6 months to 18 years, and ranging in size from 5 lbs to 140 lbs.

We then measured the amount of DNA methylation across the dogs’ genomes.

A conceptual diagram showing dogs of three different ages and the amount of methylation in their DNA over time.

We used that information to create an algorithm for the Age Test that can predict any dog’s age with 98% accuracy, with a range of ± 5 months to the dog’s true age.

A bell curve graphing showing a low value of 6 years 4 months, a middle value of 6 years 9 months, and a high value of 7 years 2 months.

We’re confident in the accuracy of our Age Test, which has a Pearson correlation coefficient of 0.995.

Learn more about how Embark estimates a dog’s genetic age and calendar age

How to order the Embark Age Test

The Age Test is currently in an early-access trial run. We’re releasing the test to small groups of our user base as we scale up the laboratory’s throughput. If you’re interested and don’t want to wait any longer than necessary, you can join our waitlist.

Care insights based on your dog’s age

Did you know that diet recommendations and proactive care plans can change as your dog ages? With the Embark Age Test, in addition to learning your dog’s true calendar age, you’ll get access to helpful information based on your dog’s life stage as they mature from puppy to adult to senior. Learn more about dog life stages and health considerations to keep in mind as your dog celebrates more birthdays.

Mimi Padmabandu Contributor

Mimi Padmabandu is a scientific writer and Senior Content Strategist at Embark Veterinary. Her career includes a decade of experience writing about science and genomics for leading biotechnology companies, including Illumina, Thermo Fisher Scientific, and more. She holds a bachelor's degree in Molecular, Cell, and Developmental Biology from UCLA and a master’s degree from King’s College London.

Read more about Mimi Padmabandu

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