By the time Dante turned 8, he was starting to look a little disappointed. The 70-pound mountain dog from Bern would walk around his family’s home in Interlaken, New York, like a caged bear. Then he can stand still, gazing ecstatically at the pedals of the family organ. Or in a corner of a room. In the middle of the night, he would wake up and start barking non-stop, for no apparent reason.
Then the incontinence started.
A brain scan confirmed that Dante had canine cognitive impairment, commonly known as canine dementia. It is often described as the canine analogue of Alzheimer’s disease. Some studies have shown that it can occur in at least 14% to 35% of older dogs. But because the symptoms are similar to those of other diseases, it is difficult to confirm its true prevalence.
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A large new study of 15,019 dogs enrolled in the Dog Aging Project, an ongoing study of disease and aging in dogs, published Thursday in the journal Scientific Reports, identifies the top factors associated with a dog’s risk of developing the disease.
One key finding: Exercise can play an important preventive role. The odds of being diagnosed with cognitive impairment were 6.47 times higher in dogs that were reported to be inactive compared to those that were reported to be very active, researchers at the University of Washington found. But they also said the disease itself could lead to a lack of exercise, stressing that the study’s results, which are based on observations of the owners, suggest correlation rather than causation.
The chances of developing the disease also seem to increase in dogs that have neurological disorders or impaired hearing or vision. Annette Fitzpatrick, co-author of the study and a University of Washington research professor specializing in dementia in both humans and canines, commented: “When you don’t get stimuli from the outside world, it seems to increase the risk that we can’t even use our brain”.
The study, he said, “suggests that there may be other things we can be aware of to try to reduce the occurrence of cognitive dysfunction.”
And age certainly matters. A dog’s life expectancy often depends on breed, size and body mass: think Mastiff (six to 12 years) versus Chihuahua (12 to 20 years). During the last years of a dog’s expected lifespan, each successive time contributed to the likelihood of developing the disease, the study found.
In fact, the researchers noted, the risk factors associated with cognitive impairment in dogs mirror some of those for people with dementia, including Alzheimer’s disease.
Previous studies of cognitive dysfunction in dogs often relied on veterinary assessments of smaller populations of older dogs. This is killed by dogs ranging in age from a puppy to their mid-20s. In the coming years, as these dogs get older, the project, which has enrolled more than 40,000 dogs and hopes to reach 100,000, will produce more complex findings about cognitive dysfunction and other diseases.
In this study, the prevalence of canine cognitive impairment in all dogs, young and old, was 1.4%. But the average age of the dogs was just 6.9 years and only 19.5% of the dogs analyzed were in their last trimester.
“This study compares dogs with cognitive impairment to those without,” Fitzpatrick said. “But as the years go by, we can see the same dog that may have had excellent cognitive function but then declined.”
The results came from a single baseline accounting by owners of their dog’s health and lifestyle experience between 2019 and 2020, and a high-stakes cognitive function questionnaire.
Among the questions:
— How often does your dog pace, walk in circles, and/or wander without direction or purpose?
— How often does your dog get stuck behind objects and unable to move?
— How often does your dog run into walls or doors?
— How often does your dog have trouble finding food on the floor?
If the study’s findings have a familiar, even intuitive, ring, that may be because the Dog Aging Project, which receives funding from the National Institute on Aging, a branch of the federal National Institutes of Health, can provide insights into factors that they affect the lives of the people and dogs who share their homes.
Unlike laboratory animals such as flies and mice, companion dogs are affected by their owners’ environmental and social factors, such as secondhand smoke, lawn pesticides and access to health care.
“Estimates of human longevity say that it’s about 75 percent environmental and 25 percent genetic,” said Matt Kaberlein, a biogerontologist at the University of Washington who co-directors the Canine Aging Program. “So companion dogs give us an opportunity to really understand the role of this environmental variability in the biological aging process.”
In addition, because dogs age much faster than humans, the studies conducted under the project provide opportunities on an accelerated timeline for information on human and canine aging.
Kaeberlein’s motivation comes not only from his professional background but also from his many years as a dog owner. He shared stories of Chloe, his lively, loving, now-deceased Keeshond, who began staring blankly and tangling with furniture, stricken with canine cognitive dysfunction. Or Dobby, his current inspiration, the family’s long-haired German shepherd who “is just a special dog” but who, at 12, has already beaten back cancer once and can no longer climb into the backyard to chase the bubbles with a stick.
“I would love it if my dogs could live longer,” Kaeberlein said. “And I would love it if I could help other people’s dogs live longer.”
Trials underway under the project, which began in 2014 and has researchers from the University of Washington and Texas A&M, as well as the Cornell University College of Veterinary Medicine and other universities, include those for drugs that potentially expand life and a tissue biobank donated by owners of dead dogs. He published a study that shocked the dog world because it found that better dog health is associated with just one daily feeding.
(As Kaeberlein discussed this correlation during a phone interview, two highly motivated small canines who had been snuggling next to this reporter sat up abruptly, whining and howling in protest. Kaeberlein was quick to add that her observation study is more likely a commentary on obesity and morbidity than a prescription for feeding frequency, which is consistent with the latter study’s positive association with exercise.)
Canine cognitive dysfunction is difficult to detect. A dog’s seeming ignorance of a routine command could indicate deafness or old-age stubbornness rather than an atrophying brain. Symptoms that look like cognitive impairment could actually be from a stroke, brain inflammation, diabetes or Cushing’s disease, said Dr. Nicole Ehrhart, a veterinarian and director of the Columbine Health Systems Center for Healthy Aging at Colorado State University.
Vets first rely on the owner’s keen observation, he said, and then run diagnostic tests.
“Watch your dog look into your eyes and see how long he holds your gaze, especially if you have a treat in your face,” she said. “Because as dogs suffer from dementia, they can’t focus on things they would normally focus on.”
Ehrhart, who was not involved in the Dog Aging Project study, called the new research “a wonderful confirmation of something we know across species: that exercise is good for healthy aging, and that lifelong exercise habits can be preventative for Alzheimer’s disease and other cognitive problems.
In fact, the average life expectancy for Bernese Mountain Dogs is six to eight years. Dante is now 11. But he was especially active in his younger years: He had the physical and mental acuity to happily navigate complex obstacle courses and leap impenetrably from upper stairs with a single bound.
But now, the typically amorous Berner is shunned by his family pack—three Golden Retrievers and two lovelorn, restless humans. Instead, he prefers to curl up under his favorite lilac bush, even in the rain.
“I was trying to get him to come in to be with us,” said Lisa Mitchell, his owner. “But after a year I thought, ‘Tomorrow might be his last day and maybe he’ll be more comfortable there.’ So we just conceded to let him hang out on his own if he wants to be there.”
Although there are medications and diets that can improve a dog’s cognitive dysfunction over time, Ehrhart said, owners should be sensitive to their dog’s increasing disorientation. Don’t disrupt their routine. Do not move around on the furniture. Secure your yard so the dog can’t wander off and get lost. If you want to have a loud dinner party with strangers, put the dog in a soothing environment that is not so stimulating.
And know that dogs, like older people, can experience “sunset syndrome”: increased anxiety and disorientation as the day draws to a close.
“It turns out that probably the best model for human aging has been aging alongside us for hundreds and hundreds of years,” Ehrhart said. “This is a two-way street: Anything we’re going to do to improve the health and lifespan of our dogs is likely to improve ours, and anything we do for people is very likely to improve our dogs. And who doesn’t want that?”
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