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How to determine my dog’s age in human years

How to determine my dog’s age in human years

Many pet owners, especially owners of rescue dogs, are curious about the age of their dog. Pet owners may have an approximate age of their dog based on the rescue or shelter's estimations but calculating the exact age of a dog can be difficult.

The 1 human year equals 7 dog years ratio

The most common advice to calculate your dog’s age is that 1 human year equals 7 dog years. This is actually a myth!

Popularized in the 1950s, this misconception was an overgeneralized statement based on assumptions of average human and dog lifespans. At the time, the average human lifespan was around seventy years and the average dog lived about ten years.

Surprisingly, new research has shown that there is no direct ratio of how many dog years are in a human year. Meaning you can’t convert human years to dog years to find out a dog’s age.

Dogs age more quickly in their first years of life and then even out throughout adult life until becoming a senior dog.

How can I tell how old my dog is?

While there is no perfect dog age calculator, general guidelines to calculate dog years to human years exist:

  • The first year of a medium-sized dog’s life equates to about 15 human years.
  • Year two for a dog equals about nine additional human years, making the dog about 24 in ‘dog years’.
  • After age two, each human year adds around five dog years.

Most dogs are considered puppies until their bones have fully developed and they’re fully grown. Usually between the ages of one to two years. From there, a dog is an ‘adult’ until they reach senior status.

Small breed dogs (under 20 lbs.) are considered seniors after the age of seven or eight.  Large and giant breed dogs can reach senior status as early as five or six years of age. Knowing when a dog is reaching the senior age category can help owners better anticipate the changes in care their pet may need.

How old is my dog in human years? How to find out a dog's age

The best way to find out the accurate age of your rescue or shelter dog is to get your pet’s microchip scanned at a veterinary clinic or shelter. The information stored in your pets’ microchip may reveal the original breeder or owner of the pet, who may have details about your dog’s age, plus medical history, and other important information.

However, many pets arrive at shelters without a microchip or their owner’s information isn’t registered, making it impossible to find out the pet’s exact age.

In this case, a veterinarian can provide you with a rough estimate based on one of your pet’s physical characteristics, their teeth. Especially useful in determining the age of younger dogs, dog’s teeth can reveal a lot about their general age.

3-4 weeksThe first baby teeth to appear will generally be the canine teeth.
8 weeksAll 28 puppy baby teeth have come in.
4 monthsBaby teeth begin to fall out and adult teeth can be seen coming in.
7 monthsAll 42 permanent teeth are in. Teeth appear clean and bright.
1-2 yearsOverall, teeth appear more dull and back teeth may show signs of yellowing.
3-5 yearsAll teeth may show tartar buildup and general tooth wear. Nearly 80% of dogs will show signs of gum disease like buildup of yellow and brown tartar, inflamed gums, and bad breath by age three.
5-10 yearsTeeth show significant wear and may show signs of gum disease.
10-15 yearsAll teeth will be noticeably worn with heavy tartar buildup likely if regular dental care is neglected. The dog may be missing some teeth. 

Senior dogs may also show other physical signs of aging like graying fur, stiff joints, small fatty lumps on their bodies (called lipomas), general slowing down, and behavioral changes.

Click here to view PDF of full chart

How long do dogs live in human years?

Breed and size greatly impact the average lifespan of dogs. Generally smaller dog breeds have a longer average lifespan than larger dog breeds.

Researchers are still studying why large breed dogs age faster when compared to smaller breeds. One possibility is that because they age more quickly, large dogs may succumb to age-related illnesses sooner.

Another factor is the differences in the specific types of medical conditions that affect different-sized breeds.

Lastly, genetics are a major factor when determining life expectancy for dogs. Some breeds have higher rates of hereditary illnesses and proclivity for certain medical conditions due to limited genetic variability in parent generations.

Many mixed-breed dogs have more genetic variability, which can reduce the risk of hereditary diseases.

  • Small-breed dogs, like Pomeranians and Yorkies generally have the longest lifespans, averaging 10-15 years.
  • Medium-size dogs, like Cocker Spaniels and Boxers have an average dog lifespan of 10-13 years.
  • Large-breed dogs like Golden Retrievers and Labs tend to have shorter life span ranges averaging 9-12 years.
  • Giant-breed dogs like Great Danes and Saint Bernards have the shortest average lifespan, at 8-10 years.

Remember that dog lifespans are general averages and individual dogs may or may not have a general experience. In fact, an Australian cattle dog named Bluey lived 29 years, 5 months, and is the oldest dog ever verified.

Caring for your dog at every age, from puppy to senior dog

Knowing your dog’s age is one way pet owners can give their pets the best care. Although visiting the veterinarian every 6 to 12 months is recommended to keep your dog healthy regardless of their age, they might need more frequent check-ups or receive different treatments based on the life stage they are in.

Puppies will make more frequent visits to get their vaccines, deworming, and monitor their growth. They may get spayed or neutered at this stage too.

As a young adult, your dog will receive appropriate protection against fleas, ticks, and heartworms. They will also be monitored for healthy weight and dental wellness.

As our pets age they require extra care and patience. Senior dogs may experience unseen challenges like arthritis, loss of sight and hearing abilities, diminished mental capabilities, among others.

Caring for your senior dog can include increased visits to the vet to monitor signs of illnesses or to catch and treat medical conditions early.

Ultimately, the frequency of visits to your veterinarian will depend on your dog’s health throughout their entire life and if any pet health emergencies come up.

How to help your dog live longer

Trust your vet: Following your veterinarian’s advice on routine and preventative health care like vaccinations and parasite prevention can protect your pet from preventable illnesses and health issues.

Keep Your Dog Healthy: Feeding your dog high quality food and maintaining a healthy weight can add years to your dog’s life. Dogs kept at a healthy weight live an average of two years longer than their overweight counterparts.

Maintain Dental Health: Veterinarians estimate that 80% of dogs aged three and up suffer with dental disease. Periodontal disease can lead to inflammation and damage to their vital organs. Prioritize annual dental exams and at-home dental care tools like dental chews and water additives that protect against dental disease.

Research: If adopting a purebred dog, choose a responsible breeder that tests for common breed specific diseases and is invested in the health and genetics of their dogs.

If adopting a dog from a rescue or shelter, consider a dog DNA to find out your dog’s genetic makeup and even markers that your dog may have for the genes for common diseases. Better understanding your dog’s unique genetics can help you anticipate potential health concerns that may arise.

Calculating a dog’s age in human years

Learning the specifics of a dog’s age by checking their microchip information or their physical characteristics can help pet owners to better care for their dog during every stage of life from puppyhood to senior dog; and even help their dog live a longer and healthier life.

The Lifetime Protection Plus Membership is an all-in-one pet protection service that includes 24/7 Vet Helpline, MyPetHealth Portal, 24PetMedAlert®, and more to protect your dog at every stage of life.

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