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How Do Dogs Age: Preparing for Every Life Stage

Medically Reviewed by

Tracy Isenberg, LVT

Whether you are a pet parent to a senior dog or a puppy, experiencing life milestones with your best friend is special. But, you may notice some behavior changes that make you wonder, “Is this normal?” and, “How do dogs age, anyway?”

In this article, we'll cover:

  • The aging process
  • Stages of aging
  • What aging looks like in different dog breeds
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The aging process

The aging process

The way dogs age is similar to the way humans age. As dogs get older and grow into senior dogs, they may have issues that older humans also face.

Dogs can get cancer, hip and joint issues, or simply have trouble moving around. They may also not play as much as they did as puppies.

Much like humans, your dog's health history and genetics determine how they age. And, your dog's lifespan — how long your dog lives — depends on their:

Ultimately, the speed at which dogs and humans age is different. Dogs age faster than humans. How quickly a human ages in one or two human years compared to how your pup ages is different.


How to calculate dog years

It's common for pet parents to assume that their dog's age in "dog years" is seven times their age in human years.

But, despite popular belief, dogs do not age at seven years per human year. And, simply converting your dog's age in human years to "dog years" isn't accurate.

How fast your dog ages depends on their size and breed. According to the American Kennel Club, these are the guidelines for converting dog age to human years:

  • 15 human years is equivalent to the first year of a medium-sized dog’s life
  • Year two for a dog equals about nine years in human age
  • After that, each human year would be approximately five years for a dog
VET TIP

Not sure what your dog's age is? Your vet can guess your dog's age after performing a complete physical exam and tests on your dog's anatomy at a check-up.


Stages of aging

Human and dog years aside, your pet will experience different stages of aging in their lifetime.

Here are the three life stages of aging, and what to expect as your dog ages.

1. Puppyhood

Puppyhood

Your dog is in the "puppy" stage of life from the day they are born until they are old enough to reproduce. Generally, your new dog is in puppyhood from age 0 to 1.

In the puppy stage, every single breed ages differently. Just because your dog's age may be older than 1 doesn’t mean they've got rid of their puppy tendencies.

2. Adult dog

Adult dog

Once your dog is fully grown, they are considered an adult dog. The adult stage typically ranges from 1 year to 8 years of age.

Pet owners can expect lots of behavior changes in this stage of their pup's life. Adult dogs may not need as much attention or play time as puppies. But, it's still important to maintain a healthy exercise routine to keep your dog's health top-notch.

3. Senior dog

Senior dog

Your dog is considered senior when they are 8 years old. Senior dogs usually face more life changes and health problems than puppies and adult dogs.


Signs of aging in dogs (senior)

If you have an older dog, you may notice some signs of dog aging. Some of the most obvious signs of aging in older dogs are the physical signs. As dogs mature into their old age, they may also experience some cognitive changes.

Some physical and mental signs in aging senior dogs include:

  • Grey hair: Like humans, your dog's fur on their face and body may turn grey with age.
  • Urinary incontinence: It's not uncommon for your older dog to have accidents every once in a while.
  • Weight gain: As a dog ages, they naturally become less active. And, it's normal for older dogs to gain weight and struggle with weight control. Find food that fits your dog's nutritional needs to help your dog maintain a healthy weight.
  • Hip and joint pain: Overweight large dogs tend to struggle with hip and joint issues like arthritis. That's why maintaining proper nutrition habits and monitoring your aging dog's weight is important.
  • Vision loss: In senior dogs, Glaucoma and macular degeneration are common vision loss conditions. Canine cataract — when the lens of your dog's eye is clouded over — is also a common vision condition.
  • Hearing loss: Like humans, degenerative changes in the nerves found inside the ear can lead to a loss of hearing in old dogs.
  • Health issues: As your dog grows old their immune system weakens. This can lead to health problems and other medical issues.
  • Cognitive decline: Cognitive dysfunction syndrome (CDS) is a common disease in senior dogs. The condition slowly deteriorates the brain, similar to Alzheimer's disease in humans.
VET TIP

The American Animal Hospital Association (AAHA) and the American Veterinary Medical Association (AVMA) outline senior care guidelines for pets. Pet parents can refer to these tools to care for their aging dog or cat.

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What aging looks like in different breeds

What aging looks like in different breeds

All dog breeds and sizes of dogs age differently. Here are some differences in aging dogs for different breeds.

Giant breed dogs

Bigger dogs like Great Danes tend to grow in size quickly. These quick body changes can lead to abnormal cell growth and conditions like cancer. Giant breeds are usually considered senior dogs when they turn five years old.

Large dogs

Large breed dogs like Labrador Retrievers typically live shorter lives, so they mature quickly. Like giant breeds, larger dogs are considered senior dogs around age five.

Medium dog breeds

Medium-sized dogs like Border Collies age slower than smaller breeds. Medium-sized dogs are considered senior dogs when they turn about seven years old.

Toy breed dogs

Smaller dogs like Chihuahuas tend to live longer than larger dogs. But like giant breeds, small dogs are also prone to hip and joint problems in old age. But, small dog breeds aren't considered senior dogs until age 10.


It's bittersweet to witness your best friend grow into an old dog. But, understanding how dogs age and what to expect in every life stage can help you better care for their health and keep them happy.

Support your dog's health through every life stage.