How Old Is My Dog? 4 Tips for Determining Your Dog’s Age

Jamie Lovejoy, DVM
By Jamie Lovejoy, DVM on Sep. 26, 2023
A man sits with his dog on an autumn day.

Estimating a dog’s age allows us to better understand their behavior and nutritional needs as they grow. Different life stages also require different medical screenings and vaccinations.

Converting dog years to human years can help us better understand what our senior pups (older than 11 years old in most breeds) are going through and help to provide the right nutrition or medical assistance.

In doing this, we’re able to manage our own expectations for their care and longevity.

Key Takeaways

  • Estimating your dog’s age can allow you to better understand their behavioral, nutritional, and medical needs as they grow.
  • Dogs mature much faster than we do. Most of them are the age of human teens by the time they are a year old.
  • Converting a dog's age to human years depends on the dog's breed.

Can You Determine Your Dog’s Age?

When a dog has reached their sexual maturity (usually at around six months old), it’s impossible to know their exact age based on physical exam alone.

Unlike horses—which have defined dental age markers—dogs show signs of aging based on their genetics and lifestyle.

Your veterinarian can make an educated guess about your pup’s age from their physical exam and behavior.

These estimates are close enough to help you make appropriate medical decisions, even if you don’t know the exact day to bring them birthday cake.

Your veterinarian can make an educated guess about your pup’s age from their physical exam and behavior.

Dog to Human Years Age Chart

Once you’ve established your dog’s approximate age, you may find it easier to compare their life stage to a human’s, especially when considering how long they may live.

So how many dog years is one human year? With so many different breeds and sizes, the answer to this question is a little more complicated.

A chart showing how to convert dog years to human years.

Dogs mature much faster than we do. Most of them are the age of human teens by the time they are a year old.

Life spans differ by breed, though, and an elderly Great Dane may have the same human years behind them as a middle-aged Chihuahua.

How To Calculate Dog Age

Your vet can help to determine an estimate of your dog’s age. Keep in mind they will want to factor in both physical signs and behavior when it comes to determining age.

1. Physical Signs of Age


The first thing vets look at when determining a dog’s age is their teeth. Dogs less than six months old have deciduous (baby) teeth that are replaced by adult teeth as they grow.

Baby teeth (incisors, canines, premolars, and molars) erupt and are replaced by adult teeth at very specific ages.  Because of this, puppies can often be aged accurately to the nearest week by looking at the combination of adult and deciduous teeth in their mouths.

Once a pup’s adult teeth grow in (after six months), estimating their age becomes more difficult. Tooth staining, tartar, and gum inflammation (periodontal disease) are more common as a dog ages.

Small breeds may develop periodontal disease as early as one year of age.

Your vet will look for whether your dog has all of their adult teeth as well as evaluate any signs of periodontal disease.

By comparing your dog’s teeth with those of other dogs with known ages they have seen of the same breed and type, they can give you an estimate of your dog’s age.


Gray hairs are a sign that your dog is no longer a puppy. Age-related graying is typically most noticeable on a pup’s muzzle, around their eyes, and on their paws.

Dogs differ in how quickly they gray, but it’s rarely seen in young adults. Take into consideration that scars from injury or surgery can come in with gray hairs, in which case you can rule that out as a sign of aging.

Your vet will look for gray hair on your dog’s face and paws that slowly transitions into their normal coat color to indicate that your dog may be older.


A cloudy or blue appearance to the eye (sclerosis of the lens) is a common change seen in older dogs. The lens of a young dog is made up of many clear microscopic fibers.

As dogs age, more fibers are added to the lens without changing the overall size. This makes the lens more dense and harder to see through.

White, non-see-through cataracts form when these fibers break down. This can be age-related, though these cataracts can develop from trauma, inflammation, or diabetes. Even so, dogs with these changes are more likely to be older.

Your vet will be able to differentiate sclerosis of the lens from cataracts and other eye changes that can cause similar signs (like glaucoma), using tools such as an ophthalmoscope and tonometry (checking eye pressures).

They can tell you if these changes are because your dog is older or if there may be other things going on.


Older dog paws have traveled more miles than their soft, puppy counterparts. The pads of older dogs’ paws are usually thicker and rougher. You may notice non-painful cracks or even areas where the keratin has formed small bristles.


Though exercise can mitigate this, muscle loss is very common in older dogs. This muscle loss is frequently seen in a dog’s thighs and shoulders, caused by arthritis in their elbows and knees.

The pain that accompanies arthritis decreases a dog’s mobility. Senior dogs may have more prominent spines because the muscles that run along the spine will atrophy (get smaller) with decreased activity.

Your vet will feel your dog’s limbs and back for any bony points that are not normally palpated in younger dogs.

They will consider any effect of injury (like cruciate tears, which can cause these changes in younger dogs) and breed on your pup’s muscle to help determine their age.

2. Behavioral Signs of Age


As dogs age, the nerves in their eardrums can break down, making it harder for them to hear. If you notice that your dog is surprised when you come up from behind or doesn’t bark at the door anymore, it may be a sign of hearing loss and aging.


Age-related eye changes can lead to vision impairment. Usually this is more noticeable in dim light or in full darkness.

Some dogs may be resistant to going downstairs due to poor eyesight. Normal age-related changes should not cause complete blindness, but vision can still be significantly compromised.

If your pup has cataracts, there are surgical and medical options to help maintain their vision and your veterinarian can discuss treatment options with you.

Lifestyle changes are often indicated for older dogs with nonsurgical vision problems.


Arthritis pain is a common cause of “slowing down” in senior dogs.

While limping is rare in the early stages of arthritis, older dogs may be hesitant to jump up on a couch or into a car. They may not go up or down the stairs as frequently. When they do, it can be a slow process.

Sleep/Wake Cycle

If your dog is new to you, behavior changes may be harder to evaluate. However, many senior dogs are prone to changes in their sleep cycles. They may sleep most of the day, then pace and experience anxiety at night.

These changes can be coupled with urination or defecation in the house, new anxiety behaviors, and disorientation.

If you think your dog is exhibiting these signs, ask your vet about cognitive dysfunction disorder (DISHAA) to help with tips on how to manage the condition.

When in doubt, speak with your vet.

3. Consider a DNA Test

For pet parents of mixed breed dogs, DNA tests are available to help determine what breeds predominate your dog’s makeup.

This information can be used by you and your vet to consider when you would be likely to see certain age changes with those breeds.

Some tests list common health conditions your dog may be predisposed to (like cataracts and dental disease) that should be considered when trying to determine your dog’s age.

4. Talk to Your Vet

When in doubt, speak with your vet.

Discuss these methods with them—they can help you narrow down your dog’s age range.

Featured Image:

Jamie Lovejoy, DVM


Jamie Lovejoy, DVM


Dr. Jamie Lovejoy graduated from Tufts Cummings School of Veterinary Medicine in 2012 after an undergraduate degree in Marine Biology. ...

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