By Paula Fitzsimmons
Shelter dogs don’t often come with a lot of history, which makes estimating their age a challenge. But having this information is essential to providing optimal care.
“It can help determine the most appropriate time for preventive health protocols, such as vaccination and de-worming, and the best time to test for certain common diseases such as heartworms,” according to Gainesville, Florida-based veterinarian Dr. Brian DiGangi, senior director of shelter medical programs at ASPCA.
It’s pretty easy to spot a puppy. “They have that irresistible cuteness factor and are smaller in stature,” says Dr. Michael Lund, veterinary staff manager at ASPCA in New York City. And they have obvious body characteristics, “like paws that are too large for their body size, excess and loose skin, a gangly look, and a more playful and mischievous attitude,” describes Dr. Virginia Buechner-Maxwell, director of the Center for Animal Human Relationships (CENTAUR) at the Virginia-Maryland College of Veterinary Medicine.
The best way to determine the age of a puppy is by looking at their teeth. All of a puppy’s baby teeth should erupt between 3 and 6 weeks of age and their adult teeth should appear between 12 and 16 weeks of age at the front of the mouth and between 16 and 24 weeks toward the back.
But how do you determine your adult dog’s age if you don’t know anything about her? “As a dog ages, I often look for loss of vision and hearing,” says Dr. Raymond Bouloy, a board-certified veterinarian with Cypress Creek Pet Care in Cedar Park, Texas. “Is there any loss of mobility or pain? Are there cracked, loose, or painful teeth? Is there loss of cognitive function? All these areas help me determine approximate age of my senior patients.”
Even then, it’s not an exact science. DiGangi says the signs of aging in adult dogs vary quite a bit based on breed, lifestyle, and medical history.
They also vary based on size. Smaller breeds like Chihuahuas and Terriers tend to live longer, while giant breeds like Great Danes and Irish Wolfhounds tend to have the shortest lifespans, explains Bouloy. “A geriatric Chihuahua might be 18 years of age and a geriatric Great Dane might be seven.”
Your vet is, of course, in the best position to estimate your dog’s age, but the following tips can help you make an educated guess. Keep in mind, these tips aren’t foolproof.
Many dogs get gray hair as they age (just like we do), says Dr. Kate Creevy, associate professor of small animal internal medicine at the College of Veterinary Medicine & Biomedical Sciences at Texas A&M University in College Station.
“This begins at varying ages and progresses at varying rates,” she explains. “Just like some human adults are white-haired in their 40s and others are minimally gray until their 70s, dogs can vary greatly in this trait. Graying, primarily on the muzzle, suggests the dog is a mature adult, but it does not provide a closer estimate of age than that.”
But younger dogs can go gray too. “Golden Retrievers, for instance, often start graying as early as 4 to 5 years of age,” says Bouloy, who is board certified in canine/feline practice. Other dog breeds, like Whippets, Italian Greyhounds, and Poodles, can also be inherently gray in color regardless of age.
Temperament can play a role as well. In a recent study published in Applied Animal Behaviour Science, a team of researchers studied 400 dogs ages 1 to 4 to determine how anxiety impacts premature graying. They found that anxiety and impulsivity—based on indicators like destructiveness when alone and hyperactivity after exercising—were strong predictors of muzzle grayness.
As a dog ages, the lens—the part of the eye that refracts and focuses light—begins to change. “Mild bluish-gray discoloration (cloudiness) can be observed if one looks closely into many middle aged and older dogs’ eyes,” says Lund.
Known as lenticular sclerosis, this benign condition typically appears when the dog is about 6-8 years of age. Lund says it can be a huge help in estimating ages for middle-aged and senior dogs. Lenticular sclerosis shouldn’t be confused with cataracts, a serious condition that can lead to blindness, which is also marked by a cloudy lens. He says that most often, teenage dogs start showing signs of incomplete cataracts that typically progresses to complete cataracts.
But not all dogs with cataracts are older. Lund says some breeds—including Boston Terriers, French Bulldogs, and Staffordshire Bull Terriers—are predisposed to juvenile cataract formation at a very young age, before they are 2 years old. Cataracts can also develop because of disease (e.g. diabetes) or eye injury. “But being quite rare, changes in the lens are oftentimes a great aid in picking a much more accurate age estimate.”
Just as we do, dogs have only two sets of teeth—baby and adult, says Creevy. In humans, the adult teeth begin to emerge in late childhood and early adolescence. In dogs, this occurs in the first six months of life.
After that, using teeth to estimate age is tricky, she says. “After all the permanent adult teeth emerge, they only change over time by accumulating tartar, stains, or other signs of disease. The rates at which these changes occur vary widely by dog face shape, breed background, diet, and the dental care that is provided.”
After a dog’s adult teeth have erupted, there isn’t an accurate way of aging a dog based on their dentition, says Dr. Heather Loenser, veterinary advisor for the American Animal Hospital Association (AAHA). “Well-cared for teeth in a 15-year-old dog could look healthier than a 5-year-old dog who’s been allowed to chew on hard toys.”
There are exceptions. Lund says some young dogs can have tartar and plaque buildup on their teeth fairly early in life. “But moderate to severe amounts of tartar and staining or broken teeth often lead us to rule dogs out of the youngest adult class if no other evidence for youthfulness is evident.”
If you’re up to it, take a whiff of your dog’s breath. Buechner-Maxwell says older dogs tend to have particularly bad breath, “especially if their teeth have not received regular dental care and have significant gum or tooth disease.”
“Oftentimes very active, energetic, and spasmodic dogs are younger, leading us to a prediction closer to 1 or 2 years of age, versus 5 or 6 years,” says Lund.
As many dogs age, their activity levels begin to decline. “They may have difficulty getting up or down, have trouble walking or climbing stairs, and may sleep more than they are used to,” says DiGangi, who is board certified in canine/feline and shelter medicine practices. “In some cases, older dogs may start to wake up in the middle of the night or start to have accidents in the house.”
Loenser, who also works as an associate veterinarian at Bridgewater Veterinary Hospital in New Jersey, says some dogs develop signs that mimic senility in people, a condition called canine cognitive dysfunction. “These dogs can become forgetful, confused, and seem depressed.”
This is another area where you need to consider other variables. “Injury can lead to mobility problems earlier in life that might be confused with age-related osteoarthritis,” Bouloy explains. “And your veterinarian can detect conditions like hypothyroidism (low thyroid level) that make a middle-aged dog seem like a geriatric dog.”
“Young dogs tend to be lean, fit, and flexible, while older dogs often gain weight,” Creevy says. Weight gain is typical at middle age, but with increased senior years, they tend to lose weight and develop decreased muscle tone, Lund adds.
Part of this is because dogs in their advanced years are more likely to become less active, more likely to nap, and experience a slower metabolism. “It is certainly possible to keep an older dog lean and fit—but not if we continue to feed him as much as he ate when he was very active and growing.”
Another thing dogs have in common with us as they age is the onset of more aches and pains. “As most dogs are quite active throughout their lives, there is an expectation for some joint stiffness and potential pain or discomfort as they age due to arthritis,” Lund says.
Some dogs are born with congenital conditions leading to early onset of arthritis, he says, but “more often than not, we can estimate a dog as middle age or older if arthritis is present.”