How Can You Tell How Old a Dog Is?

If your dog came into your life as an adult, it may be difficult to know exactly how old they are, but you can use certain physical features to estimate their age. Puppies tend to follow a predictable developmental path, so very it can be easier to tell their age (especially if you’re keeping track of their milestones).

Most dogs are considered adults once they are around 12 to 24 months old, depending on their size and breed. After that point, the clues about their age will be more subtle, because they are no longer growing or reaching clear developmental stages. You can make educated guesses on the age of adult dogs by looking for signs of aging, which may include changes to their teeth, eyes, muscle tone, or mobility. Read on to learn some of the specific clues to look out for. 

How can I tell how old my rescue dog is?

It may feel strange to know everything about your best friend but to have no idea how old they are. For many of us who adopt adult dogs, this is a common nagging question. We can get a decent estimate on the age of our dogs, but we may never know their astrological sign or exact age. Good estimates of a dog’s age are based on comparative knowledge of what dogs look like as they age.

A veterinarian or other veterinary professional will be able to give a more accurate estimate than someone who hasn’t studied tons of dogs. The good news is that dogs live in the now, so they won’t mind being celebrated on their Gotcha Day instead of their actual birthday. Plus, most dogs really seem to live by the adage, you are as young as you feel. Read on to learn some of the most accurate techniques for estimating your dog’s age.  

Can a vet tell you how old your dog is?

A vet can give you a more accurate estimate of your dog’s age, but they aren’t perfect at it, either. For young puppies, veterinarians can use their knowledge of specific milestones, such as when a puppy’s eyes open, when their puppy teeth grow in, and when their adult teeth grow in, to give more reliable estimates on age. Once a dog has all of their adult teeth and has reached their full-grown size, age estimates are more subjective.

Veterinarians use their experience to compare your dog with the thousands of other dogs they have examined to look for patterns like wear on their teeth, changes in their eyes, mobility issues, and muscle mass to make a general estimate of their age. With adult dogs, these estimates usually place dogs within an age range of two to five years, and it is very difficult to be more precise than that. Sometimes, additional clues may help a vet figure out your dog’s age,such as X-ray images that show open growth plates or other signs that their bones have not fully matured.

Most of the time, it is not worth the costs and risk to do this kind of analysis strictly to determine their age, but it may be found incidentally if your dog has X-rays for another reason. A lot of rescue dogs may not have had ideal care prior to adoption, including optimal nutrition, exercise, and veterinary care. As a result, they may not follow the predictable patterns of growth, development, and normal wear and tear on their bodies, which can make it more complicated to tell their actual age.

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How to tell age of dog by teeth

A dog’s teeth are a helpful clue in estimating their age. Puppies follow a fairly predictable schedule of tooth eruption, which serves as a useful guide to their age. As a general rule, the full set of 28 puppy teeth are usually fully erupted by six to eight weeks of age, with most puppies starting to have teeth around two to three weeks old. As they continue to grow, their puppy teeth will be replaced by adult teeth, starting between two and four months old. Adult canine teeth usually replace puppy teeth by about six months old. Most dogs have a full set of adult teeth by around nine months old, which includes additional premolars and molars for a total of 42 teeth.

There is a lot of variation between breeds and even between male and female dogs, so these timelines are considered a general guide with some expected outliers. A young adult dog will usually have pristine white teeth. As dogs age, their teeth become more discolored and worn. They may develop additional signs of wear, including the build-up of tartar, gingivitis, wear on the surface of their teeth, and lost or broken teeth.

All of these changes tend to be signs of aging and can be useful in estimating a dog’s age. However, dogs who have been forced to scavenge for food or survived serious illnesses or malnutrition may also have discolored teeth, worn teeth, or broken teeth that can make them appear older than their actual age. This is when your vet’s experience is useful in analyzing your dog’s overall conformation to look for other clues about their age. 

Dog behavior and physical characteristics 

A dog’s behavior and physical conformation can also provide clues about their age. These are all subjective in that they don’t occur at the exact same age for every dog. But these clues can help you home in on an age range for your dog. Some important characteristics to note include: 

• Eyes: Young dogs usually have bright, clear eyes. As dogs age, the lenses within their eyes gradually become more cloudy, which is referred to as nuclear sclerosis. Some dogs may also develop cataracts, which cause complete opacity of the lens, and this can occur at any age.

• Mobility: Puppies and young dogs sometimes appear to be made of rubber; they are so bouncy and light on their feet. They also tend to be able to run at high speeds, jump, and are very flexible. Just like humans, as dogs age, they often develop arthritis in their joints, along with other orthopedic injuries or scar tissue that limit their mobility. Some signs of decreased mobility include difficulty getting up or lying down, walking at a slower pace, difficulty climbing stairs, hind legs that slip out from under them, a stiff gait, shaking in their hind legs, or limping. Dogs who have serious orthopedic injuries or chronic disease — such as fractures, hip dysplasia, or disc disease — may show signs of reduced mobility at a much younger age than an otherwise healthy dog. It’s important to keep this in mind when using mobility to estimate their age.

• Energy level: This one is probably more obvious, but we all know that puppy energy is both irresistible and maddening. Puppies are notorious for that play-hard-nap-hard lifestyle where they get the zoomies, chew on everything in sight, and then pass out for a nice deep sleep. As dogs age, their energy levels tend to gradually decline, which may mean less frenetic energy but also more calm snuggles and hopefully better impulse control. Energy level is also very variable between breeds and dogs of different sizes. Of course, any sudden changes in your dog’s energy level may be a sign of illness and should be checked out by your vet.

• Hearing: The joys of aging can also include hearing loss for some dogs. This tends to be a gradual change for many senior dogs who have some degree of hearing impairment. Dogs of any age can also experience sudden hearing loss related to medical problems, and some breeds also carry a genetic risk for deafness, so it may not always be clear if a dog’s hearing loss is age-related. 

• DNA tests: DNA tests that can estimate a dog’s age are not available to pet parents currently but may be a useful tool in the future. Early research studies have compared elements of DNA in dogs and humans as a way to better understand the aging process in dogs. 

• Skin and pads of feet: As dogs age, their skin loses elasticity, just like humans’ skin. Skin becomes more fragile, thin, and vulnerable to injury with age. This may be reflected in paw pads that are more dry and cracked, hyperkeratosis or frilly-looking skin on their paw pads and noses, skin that bruises or bleeds more easily, and skin that seems slower to heal from injuries. Older dogs often develop more lumps and bumps as they age as a result of long-term exposure to the sun, genetics, and environmental factors. Of course, dogs who have skin disease like allergies, skin infections, or chronic conditions may appear older based on the quality of their skin too.   

• Muscle tone: Young dogs are typically well-muscled, especially breeds that are more active and energetic. As dogs age, their muscle mass decreases for many reasons. This is often evident on their backs where the points of their spine may be more visible or palpable even if they are not losing weight otherwise. They may also seem to have more prominent cheek bones and boney points on top of their head as they lose muscle mass. 

• Coat: Very young dogs may have a fuzzier appearance that later develops into a sleeker, shinier coat. As dogs age, their coats may reflect that with signs including greying of the muzzle and paws, as well as fur that is thinner, more dry, and less shiny. Fur may also grow back slower when it is clipped or shaved. Many of these signs can also occur in dogs who have had poor nutrition or underlying skin conditions; if this is the case, it’s important to call your vet.

• Cognitive dysfunction: This is the dog equivalent of dementia and is most commonly seen in geriatric dogs. These dogs often act confused: They forget cues that they previously knew, get stuck in corners, or pace or whine especially at night. While this condition is almost always a sign of old age, there are many other neurologic and behavioral conditions that have similar signs and may occur at any age. Be sure to have your vet help you make the correct diagnosis before assuming your dog’s signs are age-related. 

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When to seek expert help

If you’ve recently adopted a dog, it’s always a good idea to schedule a check up with your vet to give your new pup a thorough exam and make sure they are up to date on vaccines and other preventative care measures. This is a perfect time to also consult your vet about your dog’s age.

If you’ve had your dog for a while and are noticing physical or behavioral changes that have you questioning their estimated age, it’s also a good idea to see a vet to determine if these are normal age-related changes versus something more pressing that requires medical treatment. Any dog approaching their golden years should also have more frequent veterinary visits, at least every six months, to help manage any chronic or age-related health problems, as well as to screen for any new developments.  

Bottom line

• It can be difficult to get an exact estimate for an adult dog’s age.

• Some helpful clues to your dog’s age include the quality of their teeth, age-related eye changes, muscle mass, and energy level.

• Be sure to consult a vet if you are concerned about any changes in your dog’s health or if you want expert guidance in estimating your dog’s age.

References

• “Aging Puppies by Teeth” USDA-APHIS, July 2023. 

• Bellows, J, “Tooth eruption and exfoliation in dogs and cats,” January 2011, DVM 360.

• Dewey, C, et al, “Canine Cognitive Dysfunction: Pathophysiology, Diagnosis, and Treatment,” Veterinary Clinics of North America, May 2019, vol. 49, no. 3, 477-499. 

• Harvey, N, “How Old Is My Dog? Identification of Rational Age Groupings in Pet Dogs Based Upon Normative Age-Linked Processes,” Frontiers in Veterinary Science, 27 April 2021, vol. 8, no 643085. 

• Young, A, “Calculating your Dog’s Age,” 13 July 2020, UC Davis Veterinary Medicine Animal Health Topics.