Cats and dogs get dementia. Here’s how to spot signs and support pets.

Sullivan, also known as Sully, a Boston terrier, began behaving oddly at age 9. He would poop inside the house, circle the kitchen island and bark at nothing.

At first, his human Bridget Allen thought these acts were part of normal aging. One day, though, Sully didn’t return home from a nearby wooded area he knew well. Allen’s son found him wandering by a stream, filthy and acting confused.

A short time later, he fell off the bed while sleeping and urinated on the floor. “Something wasn’t right,” recalled Allen, a retired high school English teacher from Caledonia, Mich., about Sully’s behavior in 2012.

Her veterinarian said it sounded like “classic” dementia. “I felt like I had been kicked in the gut,” Allen said. “I had no idea that dogs could develop dementia.”

They can, and so can cats.

“We all know that Alzheimer’s disease and other dementias are among the most common conditions humans can encounter as they age,” said Stephanie McGrath, associate professor of neurology at Colorado State University’s College of Veterinary Medicine and Biomedical Sciences. “What people don’t realize is that our pets — dogs and cats — can get it, too, and it’s probably also very common.”

Experts aren’t sure how many companion animals suffer from dementia. Estimates range from 14 to 35 percent of the pet dog population age 8 and older, according to one study. Another study suggests nearly one-third of cats ages 11 to 14 and 50 percent of cats 15 and older are affected. Many experts believe these numbers are probably conservative.

“This is highly, highly underreported,” said Gary Landsberg, a Canadian veterinary behaviorist and veterinary scientific director of CanCog, an animal health research organization. “Owners need to realize that signs might be mild or subtle, so they might not have any concerns about them.”

For pet parents trying to determine whether their cat or dog has dementia, “knowing their pet’s normal behavior is important,” said Margaret Gruen, associate professor of behavioral medicine at North Carolina State University’s College of Veterinary Medicine. “You’re really looking for a change over time.”

Some signs are:

Informing a vet early about any changes in a pet’s behaviors is important because the pet may have a medical condition different from a cognitive disorder that could be treated, Landsberg said.

Many conditions, such as arthritic pain, cancer, hearing or vision loss, hypertension and chronic kidney disease, can prompt symptoms that mimic dementia in pets and must be ruled out before diagnosing a cognitive disorder, experts said.

“My 18-year-old kitty Momo has always been a vocal kitty,” Cameron said, “but when she was 15 or 16, I noticed she was vocalizing more.” Cameron suspected Momo had dementia.

Momo “became grumpier with the other cat and the dog. She was moody,” Cameron said. Bloodwork, however, revealed hyperthyroidism, or an overactive thyroid. Momo was treated, and “now she’s back to Momo,” Cameron said.

An animal can also have physical ailments and dementia concurrently, “just as an elderly person with dementia can have other age-related medical problems,” Landsberg said.

Scientists are studying pet dementia to help companion animals and their humans cope and to better understand human brain diseases such as Alzheimer’s.

“Dogs are good natural models. They can develop deficits similar to humans,” said Evan MacLean, director of the Arizona Canine Cognition Center at the University of Arizona. “Also, they can be studied more easily because they have shorter life spans than humans and can show subtle signs as early as age 7. These insights can help in learning more about the disease in humans.”

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Researchers are analyzing post-death brain tissue from pets, including one study that compares samples from dogs who had dementia with those who did not, to better understand “how the dog brain ages,” said McGrath, who is conducting the study. “We are also trying to understand when dogs who are healthy agers become dogs afflicted by dementia.”

Scientists are also studying blood and spinal fluid samples to learn if animals and humans with dementia have the same specific proteins or biomarkers indicative of cognitive decline. The findings could help diagnose pet cognitive disorders.

Some research already has found evidence of beta-amyloid plaques and tau tangles in the brains of aging dogs and cats. An abnormal buildup of both of these naturally occurring proteins, a hallmark of human Alzheimer’s disease, can disrupt nerve cell function.

McGrath is also testing three drugs in dogs — cannabidiol, rapamycin and trazodone — to see if any of them has an effect in preventing, slowing or reversing the disease.

“This is typically a chronic slowly progressive disease, with lots we can do,” Gruen said. “There is no reason why a pet with cognitive dysfunction can’t enjoy a good quality of life for some years.”

It’s unknown if cognitive disorders in pets can be prevented.

Some experts think exercise may help, as it does in humans with dementia. One recent study suggests that exercise reduces the risk in dogs, though MacLean, the lead author, pointed out that it was not conducted over a lengthy time period.

“We can say there is a relationship, but not necessarily a cause and effect,” MacLean said. “Regardless, exercise is good for everything, so it’s safe advice that giving your dog exercise would be good on a lot of levels.”

After Sully was diagnosed with dementia, and other medical conditions were ruled out, the vet suggested that Allen “take him home and love him up. You’ll know when he’s had his fill of this life.” She did just that. Two years later, after his symptoms worsened, Allen decided it was time to let Sully go.

“I felt like the essence of him was no longer there,” she said. “I couldn’t believe he would want to live like that if he had the choice. As painful as it was, I felt giving him peace was the right thing to do.”

Do you have a question about human behavior or neuroscience? Email [email protected] and we may answer it in a future column.

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