Our boy Mic’s symptoms were so subtle and their onset so gradual that we didn’t initially see them. In fact, our other dogs noticed them first. Mic, a Pembroke Welsh Corgi then 12, had always embodied good dog manners. He’d never met a dog who didn’t like him. Suddenly, he was enraging his pack-mates. We sympathized: his nighttime barking was fraying our nerves.
Though a number of vet visits and lab tests revealed nothing, Mic continued to decline. When his spatial perception deteriorated, we realized that he was acting like some elderly people we had known, and concluded, almost tongue-in-cheek, that he had “doggy dementia.”
Turns out we were right. Though many veterinarians and dog owners are unaware of it, canine cognitive dysfunction, or CCD (also known as cognitive dysfunction syndrome), affects a significant portion of the senior dog population. The advances in veterinary medicine and improved owner care that have helped dogs live longer have also increased the incidence of CCD, but as many as 85 percent of cases may go undiagnosed.
“It’s a big issue, and there’s not much awareness of it, even among vets,” says Leticia Fanucchi, DVM, PhD, a veterinary behaviorist and director of Veterinary Medicine Behavioral Services at Washington State University’s Veterinary Teaching Hospital. “I get that question—‘Dogs get dementia?’— even from colleagues.” But CCD is nothing new.
“I first started recognizing symptoms of what we now refer to as ‘cognitive dysfunction’ in dogs over 30 years ago,” says Dennis Thomas, DVM, a holistic practitioner in Spokane, Wash., and author of Whole-Pet Healing. “We didn’t have a catchy term for the disease so I called it ‘pre-senility syndrome.’”
CCD, an umbrella term for four separate cognitive forms, is an age-related neurobehavioral syndrome leading to a decline in cognitive function that can be devastating to the human/canine relationship. The forms are as follows:
Involutive depression (or depression occurring in the dog’s later years), similar to chronic depression in humans. Several factors may be involved, but untreated anxieties seem to play a key role. Because some of the symptoms— circling, wandering and house soiling—often result in the dog’s confinement, anxiety can increase, which, in turn, worsens the symptoms. Other symptoms of this form of CCD include lethargy, sleep disorders, decreased learning and vocalizing.
This often involves loss of awareness of body length and size. “Dogs with dysthymia often get stuck,” explains Fanucchi. “Behind furniture, in a corner. All they have to do is walk backwards, but they don’t know that.” Other symptoms include disrupted sleep-wake cycles; constant growling, whining or moaning; and aggressive behavior. “If you interrupt a dog while he’s in a dysthymic state, he can get mad and bite,” cautions Fanucchi. Causes of this form are thought to include hyperadrenocorticism (such as Cushing’s disease) and long-term steroid therapy.
In old dogs, hyper-aggression is associated with the dysfunction of structures related to the neurotransmitter serotonin. Cortical tumors may also be involved. “Dogs with this form of CCD lose their ability to communicate with other animals,” explains Fanucchi. “They neither give appeasing signals to other pets in the house nor understand when others send them. They bite first and warn second.”
This involves a profound decline in cognitive ability. According to Fanucchi, it is the closest thing to Alzheimer’s in humans. “They just don’t seem to learn well in any form anymore. They forget familiar features of their lives, including other pets and people. When it’s more advanced, they forget who their owners are.”
As with human dementia, the causes of CCD are not well known, but accumulations of sticky proteins called beta-amyloid plaques around neurons and the breakdown of neurons resulting in so-called neurofibrillary tangles are considered to be the leading culprits. As in humans, both phenomena affect the brain by interrupting nerve impulse transmission.