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How to Tell Your Dog’s Age in Human Years (With Signs of Aging & Chart)

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By Nicole Cosgrove

a smiling dog sitting outdoor

It turns out the old “7 dog years to 1 human year” rule might just be playground rumors. This idea dates back all the way to the 1950’s, and could have been populated by veterinarian clinics to get dog owners to bring their dogs in once a year, according to the American Kennel Club.

In actuality, according to scientists, 1 dog year might equal about 15 human years, because dogs mature faster in relation to how humans do. This isn’t a one-size-fits-all rule either; breeds and size and other factors play into how “old” your dog actually gets. So how can you tell your dog’s age in human years? Keep reading to learn more and see the handy chart!

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The Importance of Understanding Your Dog’s Age

close up of a smiling dog
Image Credit: Marliese Streefland, Unsplash

If you got your dog as a puppy, you have a pretty good idea of how old he is. But if you adopted him at an older age, it can be difficult to know his exact age.

As dogs get older, their needs change. There comes a time when your puppy no longer needs puppy food, and older dogs will reach a point where they need senior dog food. Older dogs might also benefit from more frequent vet visits.

To give them the most optimal life, you need to know how old they are so you can care for them in the best way possible.

Not a One-Size-Fits-All Formula

A dog’s size directly relates to how quickly she ages. In general, the bigger the dog is, the quicker she ages. This is why it’s not quite accurate to assume 1 dog year equals 7 human years in all dogs.

Scientists still don’t know why smaller dogs age slower than bigger dogs. It’s confusing, because large mammalian species (like elephants and whales) live much longer than smaller species (like mice). It seems like dogs should follow suit, but they do not.

Theories surrounding this fact include that the rapid growth in bigger dogs promotes abnormal cell growth (the kind that’s more likely to cause cancer) in bigger dogs. Another theory is that larger dogs are more susceptible to age-related illnesses than smaller dogs. Scientists will continue to study this phenomenon to try to understand more about a dog’s aging process based on its size.

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Dog Age Chart in Human Years

Age of Dog Age of Dog in Human Years
Small (5-20 lbs) Medium (21-50 lbs) Large (50-100 lbs) Giant (100+ lbs)
2 24 24 24 22
3 28 28 28 31
4 32 32 32 38
5 36 36 36 45
6 40 42 45 49
7 44 47 50 56
8 48 51 55 64
9 52 56 61 71
10 56 60 66 79
11 60 65 72 86
12 64 69 77 93
13 68 74 82 100
14 72 78 88 107
15 76 83 93 114
16 80 87 99 121

Using Teeth to Estimate Your Dog’s Age

One of the most reliable ways to know how old your dog is is by looking at his teeth. You likely won’t be able to tell his exact age, but at least it will give you a good idea.

Puppies under 4 weeks old won’t have many or any teeth at all. Up to 8 weeks old, puppies have a full mouth of pearly white chompers that are sharp. After about 3 or 4 months old, puppies lose their baby teeth and start to grow their permanent teeth. These permanent teeth remain clean-looking and white up until 1 year of age.

After a dog turns 1, their teeth will slowly start to yellow. Toward the back of their mouth, you will start to see stains after that first year, but the teeth will be mostly white still. By 3 years old, dogs have visible plaque buildup and more yellowing of their teeth.

When they are about 5 years old, your dog’s teeth will have lots of tartar buildup, warn down edges and be more susceptible to dental diseases. 10 years old and after, you will probably see cracked and even missing teeth.

australian shepherd
Image Credit: Nicholas Demetriades, Pixabay

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Top 4 Signs of Aging in Senior Dogs:

1. Gray Hair

old dog with white gray face
Image Credit: Pixabay

Check around your dog’s mouth, haunches, and chest. If you see some gray hair growing, your dog is showing signs of aging. Gray hair starts to grow around 7 to 10 years of age. This isn’t always a great indicator, though, as stress also causes gray hair to grow on your pup.

2. Cloudy Eyes

Dogs between the ages of 6 and 8 years old might begin to have cloudy vision and increased eye discharge. They could be developing cataracts as well, so it’s a good idea to take your dog to the vet when cloudy eyes happen. Getting old is hard enough, so it’s worth your dog’s comfort to make sure he’s not going to go blind, too.

3. Stiff Joints

saddle border collie
Image: Pxhere

Just like humans, dogs can develop arthritis and achiness in their joints when they age. This not only causes discomfort in itself, but will also discourage your pup to engage in active activities they once loved. They might have decreased mobility, too. Older dogs will have more trouble than they used to getting up on a couch or up and down the stairs.

4. Hearing Loss

An aging dog will usually start to lose his sense of hearing as well. He might not hear you call his name at the same decibel that he used to or might not hear you coming to greet him.

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Which Dog Breeds Live Longest?

Some dog breeds are known to live longer than others. These tend to be small to medium sized dog breeds, although some are on the larger side.

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Final Thoughts

We’ve talked about the ways dogs age, how to tell their age, and why it’s important to know his age. We hope this information helps you care for your dog in the best way possible, and that it adds to more memories made with your beloved pup.

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Featured Image: Jamie Street, Unsplash

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