Dogs’ risk of canine dementia rises by more than 50% each year, study finds

Dogs’ risk of canine dementia rises by more than 50% each year, study finds

Large study could aid diagnosis in dogs and improve understanding of age-related illness in humans

Dog lying on a wooden floor.

If you can’t teach your old dog new tricks, it could be an ominous sign. Researchers have found the odds of a canine having doggy dementia rises by more than 50% with each year of age.

While dementia is a well-known condition in humans, dogs can experience a similar decline in cognitive function, with symptoms including disrupted sleep, forgetfulness, walking into things, difficulties adapting to change and getting lost.

But while previous work has suggested such canine cognitive dysfunction (CCD) is more common in older dogs, as is the case in humans, studies have been small and prevalence is unclear.

Now a large study has shed fresh light on such matters in work researchers say could aid diagnosis of the condition in dogs – and even help humans.

“Given increasing evidence of the parallels between canine and human cognitive disease, accurate CCD diagnosis in dogs may provide researchers with more suitable animal models in which to study ageing in human populations,” the team wrote.

Writing in the journal Scientific Reports, researchers in the US reported how they analysed data from two surveys completed by the owners of 15,019 dogs, as part of the Dog Aging Project.

Owners were quizzed on aspects of their dogs’ behaviour including whether they had a tendency to get stuck behind objects or struggled to recognise familiar people, as well as factors such as the dog’s age, sex, breed, health and activity levels. The team then assigned each dog a score between 16 and 80, with a score of 50 or higher indicating the dog had CCD.

The results, based on data collected between late 2019 and late 2020, reveal that 1.4% of the dogs had CCD.

After taking into account factors including whether the dog was sterilised, its breed, and other health problems, the team found the odds of CCD rose by 52% with each year a dog clocks up. However, the analysis suggests prevalence of the condition is almost zero in dogs below the age of 10.

The team also reported that the odds of CCD were 6.5 times higher among dogs with lower activity levels over the past year. While the researchers said exercise may be protective against cognitive decline, they cautioned their finding could also be down to dogs with CCD being less active because of their condition, while lockdowns and other Covid restrictions may have influenced the activity level of owners and their pets.

A history of eye, ear or neurological problems was also associated with greater odds of CCD, while it appeared terriers or toy breeds may be more likely to have the condition, although the team did not report whether this finding remained after factors such as age were considered.

The researchers added that estimating which quartile of life the dogs were in helped them tell apart those with and without CCD, suggesting the approach may help indicate dogs that should be screened for the condition.

Prof Clare Rusbridge, a veterinary neurologist at the University of Surrey, who was not involved in the study, said the research helps to address how common CCD is and added weight to evidence that lifestyle influences likelihood of dementia, but said owners can take preventive measures against CCD, including the use of special diets and engaging their dog in physical, intellectual, and social activities.

Gregor Majdič, professor of physiology at the veterinary school at University of Ljubljana, said the association between CCD risk and activity had not been seen before.

“One lesson that already stems from the current study is further proof that physical activity, also in older people, is very important for the wellbeing and for keeping [the] ageing brain healthy,” he said.

Nick Sutton, dog health and science expert at the Kennel Club, agreed, but added the study highlighted a “sad irony” that while dogs are generally living longer thanks to our understanding of how to keep them healthy, the older they are, the more likely they are to suffer from age-related illness, including dementia.

“There is no cure for canine dementia or Alzheimer’s disease in humans, but by improving our understanding of these diseases, with research such as this, and by working towards a One Health approach, we can find better ways to prevent, identify, treat and eradicate these awful diseases,” he said.