If you own a dog, you've heard this rule: One year for Fido equals 7 years for you. Turns out, the math isn't that simple. Researchers now have a more accurate way of calculating a dog's age that takes into account their size, breed, and changes to their DNA over time.
Dog Years to Human Years
How do dog years work? Dogs mature more quickly than we do early on. So the first year of your fuzzy friend’s life is equal to about 15 human years.
Size and breed also play a role. Smaller dogs tend to live longer than larger ones, but they may mature more quickly in the first few years of life. A huge pup might age more slowly at first, but be nearing middle age at 5. Tiny and toy breeds don't become "seniors" until around age 10. Medium-size pooches are somewhere in the middle on both counts.
Dog Age Chart
How Do Dogs Age?
Scientists are still trying to figure out why smaller dogs age more slowly and live longer than bigger dogs. One theory is that it's related to age-related health issues in dogs. Many of these tend to impact larger dogs earlier. Since larger dogs age faster, this also speeds up abnormal cell growth, which causes conditions like cancer.
How Long Do Dogs Live?
Many things can affect how long your dog lives, including their size, breed, genes, and lifestyle:
- Size and breed. Smaller dog breeds tend to outlive larger ones. On average, you can expect a small dog breed such as chihuahua, Chinese crested, and Pomeranian to be with you for around 10 to 15 years, with some breeds living to 18 years old. Meanwhile, large dog breeds like German shepherds, golden retrievers, and Labrador retrievers usually live between 8 and 12 years.
- Genetics. Their genes contribute to your dog’s lifespan. Like you, dogs inherit genes from their parents that may raise their chances of certain health conditions. That’s why it’s important to choose a breeder who uses responsible breeding practices.
- Lifestyle. Serious injuries, infectious diseases, and extra pounds can shorten dog life expectancy.
Other things have also led to dogs living longer, better lives, including advances in nutrition, medicine, and the diagnosis and treatment of disease.
Signs of Aging in Dogs
If you’ve adopted a puppy or dog but don't know their history, you may not know how old they are. Even if you don’t know the birth date, you can still guess their age.
Dog teeth should give you a rough idea of their age. These guidelines will vary from dog to dog, and they also depend on the kind of dental care (if any) they had before you got them.
- By 8 weeks: All baby teeth are in.
- By 7 months: All permanent teeth are in, and they're white and clean.
- By 1-2 years: Teeth are duller, and the back teeth may have some yellowing.
- By 3-5 years: All teeth may have tartar buildup and some tooth wear.
- By 5-10 years: Teeth show more wear and signs of disease.
- By 10-15 years: Teeth are worn, and heavy tartar buildup is likely. Some teeth may be missing.
Your vet can also guess your dog's age based on a complete physical exam or tests that look at bones, joints, muscles, and internal organs. Senior dogs might show some specific signs of aging, including:
- Cloudy eyes
- Gray hair. It starts around the muzzle and then spreads to other areas of the face, head, and body.
- Loose skin
- Stiff legs
- Bad breath
- Trouble getting around
- New lumps
- Weight changes
- Trouble peeing or pooping, or loss of bowel and bladder control
- Fear of people or objects that they once recognized
- Sleep changes (uneasiness or pacing at night)
- More barking
- Doing the same thing over and over
- Forgetfulness (cues and commands)
- Peeing and pooping where they shouldn't
- Becoming less active
Why Does My Dog’s Age Matter?
When you know how old your dog is, you can take better care of them for their entire life. Watch out for physical and mental signs of aging in your small dog around age 7 or 8, and in your large dog around 5 or 6 years old.
How to Help Your Dog Live Longer
Here are some tips to help your dog live a a longer and healthier life:
- Feed them healthy food. Use a high-quality pet food with protein, fats, carbohydrates, vitamins, and minerals.
- Keep their weight in a normal range. Talk to your doctor about how much exercise your dog should get, but in general, high-energy breeds need more exercise than low-energy ones.
- Keep their vaccines and preventives current. The four most important vaccines your dog needs are parvovirus, distemper, rabies, and adenovirus.
- Be aware of the symptoms of diseases linked to your breed of dog. Symptoms can include throwing up, sluggishness, not eating, and bloody diarrhea.
- Take them to the vet. Your dog should have a checkup and bloodwork done on a regular schedule.
- Keep them away from toxins and other harmful stuff. This includes edible and non-edible things like alcohol, caffeine, chocolate, antifreeze, fabric softener sheets, insecticides, and pesticides.
Scientific research has given us new insight into how dogs age. We now know that smaller dog breeds tend to age more slowly than larger ones. But lifestyle changes like healthier food and watching your dog’s weight can help all dogs, no matter their size, live the longest possible life. Figuring out your own pet's age can help you take the best care of them through the years.
Dog Age FAQ
How do you calculate a dog's age?
- Year 1 of a medium-sized dog's life is the same as 15 human years.
- Year 2 is around 9 years of a human life.
- Beyond year 2, a human year equals 5 years of a dog's life.
How old is 7 years in dog years?
It depends on the dog's size, but a medium-size 7-year-old dog is about 47 in human years.
How old is a 10-year-old dog?
A medium-size 10-year-old dog is about 60 in human years.
What is the dog age equivalent calculator?
In 2019, researchers at the University of California San Diego came up with a new way to figure out a dog's age in human terms. They used a concept called DNA methylation, which changes in both humans and dogs as they get older.
Researchers studied around 100 Labrador retrievers of different ages. They discovered a formula to convert a dog's age to human years by taking the natural logarithm of the dog's age, multiplying it by 16, and adding 31. While the formula isn't perfect for all dog breeds because they age differently, it's still more accurate than multiplying a dog's age by seven.