If you’ve ever met a spry 12-year-old Labrador who still chases tennis balls, or a five-year-old pup who already seems to favor naps over an evening walk, you know that age on paper doesn’t always match reality. Dogs, like humans, age at different rates, and scientists are now able to measure their pace of aging more precisely. Instead of relying on birthdays, researchers can look at something called biological age: a reflection of how your dog’s body is actually aging at the cellular level.

The Software That Shapes a Dog’s Biology

Every dog, just like humans and all other living things, is born with a genetic blueprint: its DNA. This blueprint is made of four building blocks—adenine (A), guanine (G), cytosine (C), and thymine (T). The sequence of those bases makes every dog’s code unique, like a genetic fingerprint.

But DNA alone doesn’t fully explain how dogs age. Epigenetics, the study of how external factors affect gene activity, plays a major role. Think of DNA as the hardware of a computer: unchanging and baked in from birth. Epigenetics acts like the software, telling the hardware when to run, what to run, and how much energy to put into it.

One of the key ways the software runs is called DNA methylation. This is when small chemical tags, called methyl groups, attach to DNA at certain spots—often at regions where a cytosine (C) sits next to a guanine (G). These tags don’t change the DNA itself, but they influence whether a gene is turned on, off, or somewhere in between, explains Neal Kitchen, PhD, chief operating officer at Liv Pet.

“Your dog’s environment and lifestyle can influence whether methyl groups get added to certain spots in the DNA, and those changes can shift how genes are expressed,” explained Kitchen. “In some regions, heavy methylation acts like a switch that silences a gene. In others, low methylation keeps a gene more active. These patterns work together , tuning gene activity up or down rather than rewriting the DNA itself.”

In simple terms, methylation works like a dimmer switch on a light. It doesn’t replace the wiring in your house (your DNA), but it does control how brightly or dimly the lights shine.

How Methylation Tells Us a Dog’s True Age

As dogs get older, their methylation patterns change in ways that researchers can track. Some genes slowly get silenced, others become more active, and these shifts happen in a predictable rhythm. By analyzing thousands of these chemical tags across the genome, scientists can estimate a dog’s biological age, more precisely their epigenetic age: a measurement of how quickly or slowly their body is actually aging.

This idea is often called an epigenetic clock, because it ticks along at a pace that reflects real-time cellular wear and tear. While calendar age just counts years, epigenetic age reveals whether your dog is aging faster, slower, or right on track. Two dogs of the same breed and birthday might show very different epigenetic ages, which explains why one still bolts to the door for walks while the other prefers long naps.

Why Epigenetic Age Matters for Dog Owners

The exciting part for dog owners is that epigenetic age isn’t entirely fixed. Lifestyle and environment can influence methylation, which means choices about diet, exercise, sleep, and exposure to toxins can shift how fast your dog’s internal clock ticks.

Liv Pet’s myDogDNAge scans thousands of methylation sites in your dog’s genome to provide an estimate of epigenetic age. Knowing your dog’s epigenetic age can guide how you care for them. It can influence vet visits, preventive care, inform lifestyle adjustments, and help you understand how well your pup is responding to changes in routine. Just as importantly, it highlights how dynamic aging really is—your dog’s long-term health isn’t solely written in their genes, but is also shaped by daily life.By supporting healthy habits, you may help slow your dog’s epigenetic aging and support more years of vitality by your side—on or off the couch.