Does Your Pet Have Brain Fog? Signs of Cognitive Dysfunction in Pets

Published Nov. 7, 2013

Working as I do in a veterinary practice that specializes in end of life care, the majority of my patients are elderly. I am gaining a greater appreciation for the frequency with which both dogs and cats display signs of cognitive dysfunction (similar to dementia in people).

We’re not talking about the mental changes that are typically associated with aging, but with more dramatic, abnormal behaviors. To put it in human terms, it’s okay if you don’t remember what you had for lunch a couple of days ago, but it’s not okay to forget to eat lunch entirely. The same is basically true for our pets. Signs of true cognitive dysfunction include:

Disorientation. Pets will wander or stare aimlessly and be found, seemingly stuck, in unusual places.
Loss of memory. Pets may no longer respond to previously well-understood commands or experience a loss of house or litter training.
Changes in activity levels, response to stimuli, and interactions with people and other pets. Pets can become less active or the activity that they do engage in becomes repetitive or without purpose. They may no longer be as interested in activities (meals, walks, playtime, etc.) and respond differently to people and other animals.
Changes in sleeping patterns. Pets may become restless at night and seemingly sleep all day.
Altered vocalizations. Dogs and cats may vocalize for no apparent reason or under unusual circumstances. Comforting them will usually only temporarily improve the situation.

Not a day goes by when I don’t hear from at least one owner describing one or more of these symptoms in an elderly pet. This got me to wondering what the rate of cognitive dysfunction in dogs and cats truly is, so I did a little research.

One survey estimated the prevalence of cognitive dysfunction in dogs between the ages of 8 and 19.7 years (mean age 11.6) to be 14.2 percent. Interestingly, this same study revealed a diagnosis rate by veterinarians of 1.9 percent, showing just how underdiagnosed cognitive dysfunction is in dogs. The morbidity rate (the frequency with which a disease appears in a population) for cognitive dysfunction increases with age. For example, a study showed that 28 percent of 11-12 year-old dogs and 68 percent of 15-16 year old dogs had at least one symptom that was consistent with cognitive dysfunction.

The condition isn’t as well studied in cats (isn’t that always the case?), but one paper showed that almost one third of cats between the ages of 11 and 14 develop a behavior that is consistent with cognitive dysfunction, and for cats 15 years of age and older the incidence increases to over 50 percent. Given that feline cognitive dysfunction is even less well-recognized than canine cognitive dysfunction, I think it is a safe bet that the rate of underdiagnosis in cats is even worse than it is in dogs.

Since cognitive dysfunction is a diagnosis of exclusion (the characteristic brain lesions can only be identified after death), a veterinarian and owner’s first step should always be to rule out other possible causes for a pet’s symptoms (osteoarthritis, hypertension, etc.), but once the diagnosis is made, medications and supplements are available that help some individuals. They seem to work best the earlier they are started, so if your pet is showing even subtle signs of cognitive decline, bring him or her in for an exam ASAP.