"How old is my rescue dog?" Tips and clues to determine your pup's age

July 3, 2024 - 6 min read
This article is not intended to be a substitute for professional veterinary advice, diagnosis, or treatment. Always seek the advice of your veterinarian with any questions you may have regarding your pet’s care, treatment, or medical conditions.
Four mixed breed dogs standing next to each other in order of age: from puppy to adult

“How old is my dog?” You’re not the first person to ask. 

If you bought your dog from an ethical breeder, you undoubtedly know the answer already. But when it comes to rescue dogs, it’s not always so easy to tell.

It's helpful to have to have a ruff idea. Understanding how old your dog is can help you provide the right care, nutrition, and exercise. The good news is, there are indeed some effective methods to estimate your dog’s age.

To learn how to tell how old a dog is, just read on.

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Physical signs of age

Dogs show various physical signs that can help indicate their age. By closely examining these features, you can get a better sense of how old your dog might be.


A dog's teeth can tell you a lot about their age. Puppies have baby teeth, also known as deciduous teeth, that typically emerge around three to six weeks of age and are replaced by permanent teeth by six months. In adult dogs, dental health changes gradually. You might notice tartar buildup and wear on their teeth, which indicates they're past their puppy years. Senior dogs often show more significant signs of dental wear, including tooth loss and dental disease.

So if you want to learn how to tell if a dog is old (or young), regular dental check-ups will help. Perhaps more importantly, they'll help you identify and treat dental health problems before they get worse.

Dalmatian relaxing on a carpet. He has some conjunctivitis causing black run marks under his eyes. He is also looking soulfully out of shot.Eyes

Your dog's eyes are a window to their age. Younger dogs usually have bright, clear eyes without any cloudiness. As dogs age, their eyes may become cloudy or develop cataracts, which can impact their vision. 

If you notice any changes in your dog's eyes, it's a good idea to have them checked by a veterinarian to determine if these changes are age-related or due to other canine health issues.

Coat and skin

The condition of your dog's coat and skin can provide clues about their age. Younger dogs tend to have soft, smooth coats, while older dogs may develop a rougher texture and changes in color. 

You might also see gray or white hairs appearing, especially around the muzzle. Plus, older dogs' skin can become less elastic and more prone to dryness. 

Body condition and muscle tone

A dog's body condition and muscle tone change as they age. Younger dogs are typically leaner and more muscular, reflecting their high energy levels and active lifestyles. As dogs get older, they may gain weight and lose muscle mass, leading to a more rounded appearance. (Kind of like humans.)

Activity level and mobility

Younger dogs are often full of energy, playful, and eager to explore their surroundings. In contrast, older dogs may show decreased activity levels and might experience joint-related issues like limping or hip dysplasia, making them less active. 

Every dog tends to have less tolerance for vigorous activity as they get older. Just because you’ve adopted a Border Collie or Jack Russell Terrier doesn't mean you can register them for an agility competition. Once you've assessed your pup's age, you can provide them the right amount of exercise, instead of too much. 

senior dog laying on a carpet alongside a stuffed toy while looking soulfully ahead

Behavioral signs of age

Changes in your dog's behavior can provide important clues about their age. Noticing these behavioral shifts can help you figure out where your pup is in life. 

Changes in sleep patterns

Puppies and younger dogs often have bursts of energy throughout the day and sleep soundly at night. Older dogs might start sleeping more during the day and may experience more restless nights. 

Responses to training and new experiences

Younger dogs are generally more curious and eager to learn, picking up new commands and tricks quickly. To be sure, old dogs CAN learn new tricks, but they may be more set in their ways. 

If they show a slower response to training or seem less enthusiastic about new experiences, your canine could be getting long in the canine.

Temperament and social interactions

Puppies and young dogs are typically more sociable, playful, and eager to interact with both humans and other animals. As dogs age, they might become more reserved or selective about their social interactions. They may also show signs of irritability or anxiety in situations that didn't bother them before. 

A small, fluffy dog is being examined by a veterinarian wearing a white coat and blue gloves. The vet is using a stethoscope to listen to the dog's chest. A clipboard with a pen is on the examination table in the foreground.

Veterinary methods for estimating age

Vets have specialized skills and knowledge – otherwise they wouldn't be vets. If you want to know how old your furry friend is, your best bet is to seek an expert opinion.

Dental exam

As we've already explored, veterinarians often rely on dental examinations to estimate a dog's age. A professional assessment of your dog's teeth can reveal age-related changes, such as the presence of tartar, wear, and gum disease. 

Puppies have a set timeline for losing baby teeth and growing adult teeth, which can give a fairly accurate estimate of their age. In adult and senior dogs, the condition of their teeth can provide clues about how many years they might have lived. It can also tell you whether or not they need a dental cleaning.

Physical exam

During a physical examination, a vet will assess your dog's overall health, looking for signs of aging. This might include checking for age-related conditions like arthritis, heart murmurs, and changes in skin elasticity. 

A thorough exam can help determine if your dog is experiencing normal aging processes or if there are any health issues that need to be addressed.

To recap, your vet might examine your dog for:

  • Signs of arthritis or joint issues

  • Heart murmurs

  • Changes in skin elasticity

  • Lumps or abnormal growths

  • Condition of the coat and skin

Diagnostic tests

Diagnostic tests can offer additional insights into a dog's age. Blood tests can detect age-related markers, such as changes in liver or kidney function, while imaging tests like X-rays and ultrasounds can reveal internal signs of aging, such as joint degeneration or organ changes.

To recap, common diagnostic tests include:

  • Blood tests to detect liver or kidney function changes

  • X-rays to check for joint degeneration

  • Ultrasounds to assess internal organs

  • Urine tests to identify urinary tract issues

  • ECGs to monitor heart health

Breed-specific considerations

Each dog breed has its own aging process, which can affect how quickly or slowly they show signs of aging. 

Variations in aging processes among different breeds

Different dog breeds age at different rates, and understanding these variations can help estimate your dog's age more accurately. 

Small breeds, such as Chihuahuas and Dachshunds, often live longer and age more slowly compared to larger breeds. On the other hand, giant breeds like Great Danes and Bullmastiffs tend to have shorter lifespans and may show signs of aging earlier.

Small vs. large breed aging differences

A dog's size significantly impacts their aging process. Small breeds might not show significant age-related changes until they are well into their senior years, while large and giant breeds can start to show signs of aging as early as five to seven years old. 

Knowing the typical lifespan and aging characteristics of your dog's breed can provide a better context for interpreting physical and behavioral changes.

Old mutt terrier dog lying down on the floor next to a couch

Tips for pet parents

As dogs age, their care requirements evolve. Here are some practical tips to help you adjust your care routine to meet their changing needs.

Keeping track of your dog’s health

Regular veterinary check-ups are vital for monitoring your dog's health as they age. You can also keep a health journal to document any physical and behavioral changes you notice. This can help you and your vet spot patterns and address potential issues early. 

Monitoring your dog's weight, appetite, and activity levels can also provide valuable insights.

Adjusting care as your dog ages

As your dog gets older, their care needs will change. You may need to adapt their diet to include senior-specific food that supports joint health and digestion. Adjusting their exercise routine to be less intense but still engaging is also important. 

Providing appropriate medical care and vet-approved supplements, like joint supplements or medications for chronic conditions, may help your dog maintain their quality of life.

Better quality of life for your senior dog

If you adopt a senior dog, you can bring them a whole lot of comfort by making a few home modifications. Consider adding ramps or steps to help them navigate doorways, furniture, and other high areas. And give them a comfortable, supportive bed to alleviate pressure on their joints. 

Mental and physical enrichment tailored to older dogs, such as gentle play and puzzle toys, can keep them engaged and happy.

Whether your pup is young or old, dog insurance can help you manage their care. ManyPets policies are designed to reimburse you for accident and illness costs including treatments, medications, hospitalizations, and more. (Certain exclusions apply, including those for pre-existing conditions.)

Learn more:

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David Teich
Lead Editor

David oversees content strategy and development at ManyPets. As Lead Editor, he focuses on delivering accurate information related to pet care and insurance. David’s editorial background spans more than a decade, including a pivotal role at Digiday, where he wrote content and managed relationships with media and tech companies. As an Associate Editor at Cynopsis Media, David wrote the Cynopsis Digital newsletter and interviewed executives and digital marketing experts in the TV industry. His background also includes film journalism. His diverse experiences in journalism and marketing underpins his role in shaping content within the pet care industry.