How To Calculate Dog Years To Human Years?

The concept of "dog years" had its roots in trying to put a human-like perspective on our furry friends' shorter lifespans. 

The widely adopted belief that one dog year equals seven human years emerged a few decades ago and was a handy rule of thumb. However, recent scientific advancements offer more detailed and accurate ways of calculating dog’s age in human years.

Looking back, the seven-to-one ratio simplified the observation that dogs generally age faster than humans. As we know more and more about dogs, we've moved beyond this simplistic approach to gain a more accurate idea of a dog's life expectancy.

The commonly used formula of "one dog year equals seven human years" has been debunked as inaccurate. 

The researchers at the University of California, San Diego, in 2019 introduced a more sophisticated formula that takes into account the DNA changes between humans and dogs.

In both, these methyl groups modify DNA activity without altering the DNA itself. Scientists have harnessed this phenomenon, known as DNA methylation, to create an "epigenetic clock" for studying the aging process in humans.

The research team conducted targeted DNA sequencing in 104 Labrador Retrievers spanning a 16-year age range. The goal was to compare the epigenetic clocks of dogs with those of humans, which resulted in this formula: 

human_age = 16ln(dog_age) + 31. 

If you’re not a fan of using formulas, here is how the American Veterinary Medical Association  simplifies it:

• The first year of a dog's life is equivalent to 15 human years
• The second year to about nine human years
• All the subsequent years are approximately equal to four to five human years each

For those who prefer a simpler approach, researchers have also provided an alternative method using a chart. This user-friendly chart categorizes dogs by size (small, medium, and large, under 100 lbs) and breaks down the first few years of a dog's life into human equivalents. 

The new method recognizes that different breeds age differently as breed and size can affect the life span of a dog. Small dogs, for instance, tend to have longer lifespans than larger dog breeds. 

American Kennel Club provides a comprehensive dog year-to-human years chart for calculating a dog’s age, which takes into consideration the dog’s size as well: 

Source: American Kennel Club. A chart displaying the ages of dogs in human years according to the updated formula regulated through the Epigenetic Study in 2019, taking into account factors such as their ages and sizes.

By size, dogs are generally divided into four categories. 

• Smaller breeds or smaller dogs which weigh around 20 pounds or less

Examples include the Chihuahua, Pomeranian, and Yorkshire Terrier.

• Medium-sized dogs weighing between 21 to 50 pounds. 

Examples include the Cocker Spaniel, Beagle, and Bulldog.

• Large breeds or large dogs weigh between 50 to 100 pounds

Examples include the Doberman, Alaskan Malamute, and Siberian Husky

• Even larger breed dogs weighing more than 100 pounds are considered giant breeds. 

Examples include the Great Dane, Saint Bernard, and Tibetan Mastiff.

Much like us, dogs show signs of aging as the years go by. Keep a keen eye on the following indicators to ensure your dog's well-being and provide them with the care they deserve:

• Dental Transformations: Changes in teeth, including wear and tear or the appearance of tartar, can signal aging in dogs.
• Gray Muzzle Syndrome: Just like humans, dogs may experience graying hair around the muzzle as they grow older.
• Diminished Eyesight: Watch for signs of poor eyesight, such as difficulty navigating familiar spaces or reluctance to engage in activities that require visual acuity.
• Auditory Changes: Trouble hearing is a common age-related concern in dogs. Pay attention to their response to commands and their reaction to sounds.
• Stiffened Muscles: Aging can lead to stiffness in muscles and joints, affecting your dog's mobility. Observe any reluctance to engage in physical activities or changes in gait.
• Decreased Activity Levels: A reduction in overall activity can be a clear indication of aging. Note changes in playfulness, exercise enthusiasm, or daily energy levels.
• Behavioral Shifts: Aging can bring about alterations in behavior. Keep an eye out for changes in temperament, dog sleeping positions, interactions with family members, or responses to familiar stimuli.

So, now you know…

The commonly known multiply by 7 method isn’t quite the best or most accurate one. Now that we have a helpful formula and chart, you can easily calculate your dog’s years in human years.