But today’s visit was different.
“He just hasn’t been himself for the past several months,” owner Carol reported. “He seems restless at night, but mostly he just lays around. He doesn’t play his old games anymore. There isn’t any single issue, but he just isn’t right.”
Carol came in because Zeigfield had been urinating and defecating indoors, despite being well house-trained since puppyhood. After ruling out most possible physical causes, I told Carol that her dog was likely developing dementia.
Pets live very different lives than when I started my veterinary practice 40 years ago. Dogs no longer run freely outside to be hit by cars, fight with other animals or eat out of garbage cans. The quality of dog food is considerably better, and we’ve controlled most deadly infectious diseases.
In short, dogs’ lifestyles are safe but sedentary, leading to longer lives but also chronic conditions like obesity, arthritis and cognitive dysfunction. I find myself diagnosing this almost daily at the Southern California veterinary hospitals where I practice.
People are often surprised that their pets can develop something like human Alzheimer’s. But really, our brains are not that different from dogs’. The cellular changes of canine cognitive dysfunction would be recognizable under the microscope to any human brain pathologist: Plaques of beta amyloid — protein fragments believed to be the result of “oxidative stress” — lead to distinctive “neurofibrillary tangles” within the damaged nerve cells, and shrinkage of the brain appears in areas where memories are made and behaviors are shaped.
Some things are different between our species, of course. Fido doesn’t forget where he put his car keys. But he may not remember which door he uses to go out to the yard. The same inability to evaluate behavioral appropriateness may prompt a person with dementia to disrobe in public, or a dog with dementia to eliminate in the house without hesitation. Many dogs with cognitive dysfunction wander restlessly all evening in a manner reminiscent of the “sundown syndrome” of Alzheimer’s patients. And most significantly, finding familiar surroundings strangely unfamiliar often triggers anxiety and agitation.
When I explain such anxiety to owners of senile dogs, I often refer to a scene in the movie “On Golden Pond,” in which Henry Fonda’s character leaves the house to pick strawberries and returns a few minutes later, shaking and distraught. “Nothing was familiar, not one damn tree,” he says. “I was scared half to death.”
As with many of the dogs I treat, Sterling, a 14-year-old Labrador retriever from El Cajon, was dealing with dementia along with other health problems. He had recently lost most of his hearing, and arthritic hips made it difficult for him to rise from his favorite sleeping spot. Sterling spent hours every night panting and whining. Once he got to his feet, he could move fairly well. But as soon as he left the house for a walk around the neighborhood, he pulled nervously at the leash to get back into the house, where he would pant and tremble for the next hour. Sterling’s owners felt that he was suffering, and they had started to consider euthanasia.
Once a dog’s cognition deteriorates, it loses the ability to compensate for discomfort, and the dog’s suffering becomes compounded by anxiety. This is the point at which most compassionate owners I’ve dealt with have made the difficult decision to euthanize their long-time companion. Although dementia is almost never fatal on its own, cognitive dysfunction and physical health problems are a debilitating combination.
Treatments for canine dementia are most effective when they are started before the signs of cognitive dysfunction start to show. This is equally true in humans, which is why researchers are working on tests to predict Alzheimer’s long before symptoms appear. A number of nutritional supplements (particularly DHA, one of the omega-3 fatty acids found in fish oil) and various antioxidants have been shown to slow the progression of mental decline. S-AdenosylMethionine (SAMe) is an over-the-counter supplement that provides mild help for old brains. There is even an FDA-approved medication to treat canine cognitive dysfunction: Seleginine is a derivative of a drug used in human Parkinson’s Disease. In my personal experience, I have not seen dramatic results with this medication, but it is usually prescribed in the later stages of dementia, when it may be “too little, too late.”
We can also borrow from the extensive research that has been done in humans and laboratory animals, which find that eating a healthy diet (high in omega-3), staying mentally active and getting lots of aerobic exercise can delay the onset of senile dementia. The exact amount of exercise that is required to delay senility in dogs has yet to be studied, but my personal experience has been that when I see one of my canine patients who is still alert and happy at 15 years old, the dog’s owner invariably tells me, “He has always gotten out on his walks every day, no matter what.”
When we are in the middle of our busy lives, old age seems far away, and taking steps to delay senile dementia (for our dogs or ourselves) isn’t a priority. There is even a certain unspoken acknowledgment that old age and a weak mind are inexorably linked. It isn’t until your graying canine companion is anxiously pacing the house at midnight or your mother forgets your name that you think you’d do anything possible to bring back the memory and comprehension that has been lost. Something to think about while you take a long walk with your dog.
This piece was written in partnership with Zocalo Public Square.