Pets are living longer than ever before. In the past four decades, dog life expectancy has doubled, and housecats live twice as long as their feral counterparts.1 Much of this can be attributed to better veterinary care and better diets, but it comes with a downside.
As we extend the life expectancy of our pets, we’re seeing more age-related illnesses and conditions that weren’t common—or even thought to be possible—before. One of these is canine cognitive dysfunction, commonly known as dog dementia.
There are several contributing factors to a dog developing dementia. Age is an obvious risk factor, but breed, health history, and size may all play a role.
What Is Canine Cognitive Dysfunction?
Canine cognitive dysfunction (CCD) is a neurodegenerative disorder that causes behavioral changes and cognitive defects. Like human dementia, CCD presents with clinical signs like disorientation, incontinence, sleep disruptions, progressive loss of memories, and decreased social interaction.
Understanding dog dementia wasn’t a priority in veterinary medicine until the 1990s. As more dogs presented with cognitive impairment, however, more data was collected and contributed to the understanding that dementia is a clear cognitive degenerative process, not another health condition.
How Common is Dog Dementia?
It’s difficult to get clear data on the prevalence of dog dementia for several reasons, including the relative lifespan of dogs. The age at which dogs begin to show signs of cognitive decline varies, with up to 60% of dogs older than 11 years being affected.
This presents challenges with large or giant breeds. As many who own these breeds know, they have much shorter lifespans than small or toy breeds. If they don’t live long enough to reach the “window” of dog dementia, they’re less likely to show the signs. CCD may be more common among smaller breeds, but that could be a product of a longer lifespan rather than the breed themselves.
There’s also recent research indicating that CCD may be more common in dogs that have been spayed or neutered. More research is needed, but these limited studies may indicate that hormones have a neuroprotective effect.
Which Breeds Are Prone to Dementia?
With more dogs—and their owners—experiencing CCD and looking for answers and solutions, more studies have been conducted to understand and address dog dementia.
Until recently, most CCD studies were small and didn’t yield broad conclusions. Then, in 2018, Sarah Yarborough of the University of Washington conducted a study with 15,019 dogs and data obtained from the National Institute on Aging and a number of surveys. Broad health data was included in the study, such as demographics of both dog and owner, physical activity, behavior, environment, diet, medications, and health status.
The results revealed a lot of connections between risk factors and CCD, including poor health history. Dogs with a history of neurological eye or ear disorders were found to be about twice as likely to have CCD—a factor that increases the risk of Alzheimer’s in humans.
The study also reinforced the previous connection between sexual status and the risk of CCD. In this particular study, however, dogs that were intact had higher odds of CCD compared to spayed or neutered dogs.
Then, the breed. The dogs in the study were divided by breed, and those classified as terriers, toy breeds, or non-sporting breeds, according to the American Kennel Club, were over three times as likely to have CCD compared to other breed classifications.
Of course, many of these breeds are small and long-lived, such as the Chihuahua, Papillon, Miniature Pinscher, Boston Terrier, French Bulldog, and Pug. If dementia is 40% to 50% more likely to present at the age of 14 or older, and the risk increases with each year, it follows that these breeds will live long enough to show signs.
Aside from age, the risk of CCD is complicated by many factors, including the dog’s breed or breed size. Nothing can be done to change a dog’s breed or their predisposition to CCD, but more research is needed to indicate the role of diet, sterilization, and health history. While it’s possible that we may develop treatments to slow the progression of dog dementia in the future, for now, we can only do our best to care for our dogs as they enter their golden years.
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