Beyond gray muzzles: defining aging in dogs

November 10, 2020 - 8 minutes read

Our Senior Dog Care Series focuses on common challenges that older dogs face and provides helpful tools and suggestions to help your senior dog maintain an optimal quality of life for as long as possible. Find more articles in the series here.

Photo by Christian V.

What is aging exactly?

Answering this question is not only the necessary starting point for this blog series, but it is also one of the primary aims of the Dog Aging Project. Even though recognizing aging is simple enough when we see an elderly dog with a white muzzle, truly defining aging in dogs is much more challenging.

In human health, there are standard tools used by physicians to assess the aging process. These include physiological parameters, physical assessments, and various cognitive tests. Unlike in humans, there are no clearly defined parameters to define, monitor, or predict the aging process in dogs.

Researchers at the Dog Aging Project are developing metrics that can be used by veterinarians to assess where an individual dog is in the aging process. Those metrics can also be used to identify factors that influence healthy aging and healthspan, the period of life spent healthy and free of disease.

Some people wonder when their dog is actually considered a senior dog. After all, AARP doesn’t start sending them membership applications in the mail! Until we complete our research and have better tools to assess aging, the veterinary community is reliant on some general guidelines related to size, average lifespan, and our observations of physical and behavioral changes to identify senior pups.

We know that size is one of the primary factors that determines the rate of aging in dogs. Size is also easily measured and thus is often used as the sole factor to define senior status. We know this is an oversimplification of the complex aging process, but until our genetic and physiological studies are completed, the guidelines below are still a good indicator of when your pup should be considered a senior. As you can see, in general, larger dogs age faster than smaller dogs.

  • Small (2-20 lbs) and medium breeds (21-50 lbs) are considered seniors at 7-10 years old.
  • Large breeds (51-90 lbs) are considered seniors at 5-8 years old.
  • Giant breeds (90+ lbs) are considered seniors at 5 years old.

A more individualized way to define senior status in specific breeds is to look at the average lifespan for that breed. The American Animal Hospital Association (AAHA) Senior Care Guidelines recommend that we apply senior status to dogs when they are in the last 25% of their predicted lifespan. If you want to calculate this value for your dog, look up your dog’s breed (or primary breed if mixed) in this table*. Senior status begins at average lifespan multiplied by 0.75.

*Source: Adams, V.J. et. al. Methods and Mortality Results of a Healthy Survey of Purebred Dogs in the UK. JSAP (2010) 51: 512-524.

Another tool employed by veterinarians to determine senior status is careful observation of changes in the dog’s physical and behavioral characteristics.

Some common physical changes that might occur with age include:

  • Gray muzzle, gray fur, or gray whiskers
  • General decline in coat quality or hair loss
  • Soiled, greasy, matted, rough-looking coat
  • Wrinkled or thickened skin or paw pads
  • Callus formation
  • Malformed or brittle nails
  • Cloudy eyes
  • Dental wear and tear
  • Muscle loss
  • Weight loss or gain
  • Decreased mobility
  • Loss of balance
  • Stiffness or weakness in limbs
  • Decreased caloric requirements
  • Decreased vision or blindness
  • Decreased hearing or deafness

Some common behavioral changes** that might occur with age include:

  • Disorientation or confusion (e.g. getting ‘stuck’ behind objects or in corners)
  • Change in normal interaction with people or other pets (e.g. ‘aloof’, ‘clingy’, irritable, aggressive)
  • Increased time spent sleeping
  • Restlessness, especially at night
  • Loss of housetraining
  • New or worsening anxieties or fears
  • Inappropriate or excessive vocalization
  • Decreased exploration, activity, and/or play
  • Decreased interest in eating and drinking
  • Increased repetitive activity (e.g. pacing or compulsive licking)
  • Learning difficulties and/or memory loss (e.g. failure to recognize familiar people or other pets)

**We’ll be looking at common cognitive changes including those listed above in more detail in our next blog post in this series.

Every dog is unique, and not all dogs will exhibit these common signs of reaching senior status. Also, it is VERY important to realize that while all of these conditions may be age-related changes, a number of these can also be caused by diseases that require medical attention. It can often be quite difficult to distinguish between age-related changes and disease-related changes. This is why it is VERY important to discuss any changes you observe, such as those listed above, with your primary care veterinarian.

While participating in the Dog Aging Project, you will notice that many of our surveys ask our participants to reflect on the physical and behavioral changes they observe in their canine companions over time. You are the expert when it comes to your dog, and your day-to-day observations of what is (and is not) changing in your dog are incredibly valuable to our research. In combination with the genetic and physiological components of our study, the answers you provide in various surveys will be used to develop the first comprehensive definition of canine aging!

Do you know who this benefits? Our beloved senior dogs, that’s who! We can’t wait to show our elderly puppers all the love, all the time!

Please keep in mind that while our team is full of experts, we can’t ethically offer medical advice. We urge you to discuss your dog’s unique situation with your primary care veterinarian because they are the experts on your dog’s particular history and needs.

McNulty, Kellyn

Dr. Kellyn McNulty, DVM
Research Team