Disease Background: Cognitive dysfunction syndrome
Dr. Gary Landsberg: For our discussion today, we have gathered veterinary behaviorists and practitioners from North America and Europe, a psychiatrist
who treats people with depression and Alzheimer's disease, and a pharmacologist with a special interest in drugs that affect
the nervous system.
"If we can get owners to understand the disease process, the signs to look for, and the fact that therapies exist, they might
volunteer the information much earlier." - Dr. Gary Landsberg
Let's begin by defining age-related cognitive dysfunction in dogs. In North America, we use the term cognitive dysfunction syndrome to describe a spectrum of clinical signs that relate to perception of stimuli and to memory and learning. The clinical signs,
which can start months or years before owners become aware of them, are primarily caused by age-related changes in the brain.
It is important that practitioners identify the clinical signs. Several studies have looked at the frequency of cognitive
dysfunction in dogs. In one, researchers found that at least 68% of dogs 15 to 16 years old had one or more clinical sign
of cognitive dysfunction.1 Twenty-eight percent of dogs aged 11 or 12 years also had at least one sign.
The diagnosis of cognitive dysfunction is a diagnosis of exclusion. Practitioners must remember two things. First, in aging
pets, medical problems can contribute to many of the same clinical signs of cognitive dysfunction so you have to rule out
medical causes. Second, even if you find medical causes, the dog can still have concurrent cognitive dysfunction.
Landsberg: Now let's talk about the clinical signs associated with cognitive dysfunction. In North America, we often use the acronym
DISHA, which stands for disorientation, interaction changes with family members and other pets, sleep-wake cycle alterations,
housetraining loss, and activity level changes (both increase in repetitive activities or decreased overall activity). What
are the most common signs associated with early cognitive dysfunction?
Dr. Amanda Florsheim: Dogs are usually presented to me because of housesoiling or a disturbance in their sleep-wake cycle. These signs disrupt
owners' lives, so they are what general practitioners see.
Landsberg: Owners don't always report these subtle signs. Do you have any suggestions for identifying these signs as early as possible?
"Behavior modification and management are important in cases involving any older dog, whether it is showing obvious signs
of cognitive dysfunction or not." - Dr. Amanda Florsheim
Florsheim: At my clinic, we are implementing a standard questionnaire for dogs older than eight years. This form asks questions about
these subtle signs, such as: Have you seen a decrease in play? Does your dog seem to sleep more during the day? We ask about
subtle signs early, rather than waiting for the more dramatic signs to appear later.
Dr. Valerie Dramard: As the disease progresses, disorientation becomes another sign of cognitive dysfunction. The dog gets lost in the garden
or in its neighborhood. Or when you open the door to let it outside, the dog is on the wrong side, standing next to the hinges.
That is quite bizarre to owners.
Landsberg: If a dog is brought in for housesoiling or night waking, how would you determine it has cognitive dysfunction, as opposed
to some other problem?
Florsheim: We run a complete blood count, serum chemistry profile, urinalysis, and urine culture to rule out as many medical causes
as we can. We also conduct a thorough neurologic exam.
"The earlier you institute the treatment, the better the outcome."- Dr. David Mischoulon
Landsberg: You should do a complete workup that is not more extensive than necessary. In some cases, an MRI or CT scan might be appropriate,
whereas in cases with no neurologic abnormalities or with signs related to other organ systems, these tests might be unnecessary.
Several years ago, I was on a panel of the American Animal Hospital Association that set up senior care guidelines. Those
guidelines recommend annual examinations at middle age and twice-a-year examinations as pets reach their senior years. This
is the time to take a good behavioral history. It is critical to talk with the owners at every year's checkup—these are the