Pet Factsheets

Cognitive dysfunction syndrome

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Cognitive dysfunction syndrome (CDS) in dogs and cats can be compared with Alzheimer's disease in humans, although the conditions are not identical. Before diagnosing CDS, your vet may want to rule out other medical conditions that can cause similar clinical signs. Medications can help some pets with CDS. There is a diet for dogs with CDS, and nutritional supplements may also help manage the problem in pets.

What is cognitive dysfunction syndrome?

Elderly dogs and cats develop a very similar condition to Alzheimer's disease or senility in people. This condition is known as cognitive dysfunction syndrome (CDS).

Researchers are still trying to understand all the changes that occur in the brains of pets with CDS, but studies have determined that deposits of a protein called beta-amyloid play a role. These deposits have an adverse affect on brain functioning.

The exact prevalence of CDS in dogs and cats is not well documented, but evidence suggests that the disease becomes more common as pets age. In one study, CDS affected 47% of dogs between the ages of 11 and 12 and 86% of dogs between the ages of 15 and 16.

What are the signs of cognitive dysfunction syndrome?

Some of the subtle clinical signs of CDS can be difficult to distinguish from regular signs of ageing. These include things like slowing down and becoming less active. However, dogs and cats with CDS also exhibit other signs, including the following:

  • House soiling ("forgetting" how to use the litterbox or eliminating outside the box for cats)
  • Decreased activity and attention
  • Disorientation
  • Changes in sleep cycles (pacing or wandering and crying at night)
  • Withdrawing from interactions with family members

Some pets can seem to not know family members and even exhibit aggressive behaviour toward other pets or members of the household, as if they are strangers. Pet owners may also report that a pet has "forgotten" tricks, behaviours, and regular routines that were well established earlier in life.

How will my vet diagnose cognitive dysfunction syndrome?

Your vet will likely begin by reviewing your pet's medical history. Valuable information can include the duration of the observed abnormalities, the severity of the problem, and whether the problem seems to be getting worse over time.

The most important aspect of diagnosing CDS is to rule out other medical problems that can cause similar clinical signs. For example, an elderly cat that starts soiling outside the litterbox may have another illness such as a bladder infection, diabetes, thyroid disease, or a kidney problem; all of these conditions can cause increased frequency of urination. Similarly, a cat that has arthritis may have difficulty getting into and out of the litterbox and therefore be reluctant to use it. Senior pets can also begin to lose their vision and hearing, which may affect how they interact and respond to family members.

Your vet may recommend a variety of diagnostic tests to rule out other medical issues before making a diagnosis of CDS. Preliminary tests may include the following:

  • Blood tests, including a chemistry panel and complete blood cell count (CBC)
  • Urinalysis and urine culture testing to evaluate kidney function and look for evidence of kidney or bladder infection
  • Radiographs (x-rays) to look for evidence of arthritis and to check for cancer or other changes involving organs in the abdomen or chest
  • Abdominal ultrasonography
  • Specific blood tests to evaluate thyroid function and look for other medical condition

How is cognitive dysfunction syndrome treated?

There is no cure for CDS but treatment may help improve the signs and slow the progression of the disease. Depending on the severity of the clinical signs, there are medications that can help dogs with CDS, but there is currently no licensed medication for cats with the condition. There is a diet that can help dogs with CDS, and nutritional supplements may also help manage the problem in pets.

There is no single medication that can help all pets with CDS. However, it has been shown that exercise and mental stimulation can help slow the progression of CDS. Regular exercise that is appropriate for an older pet, combined with environmental enrichment with toys and play activities, may help keep pets more alert as they age.

If the problem becomes too severe and issues such as house soiling, aggression, and poor quality of life become intolerable, euthanasia can be a reasonable option to discuss. Your vet can help you and your family sort out these issues and try to help you make the best decision for you and your pet.