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This archive article (written 2009–2016) contains advice that may be out of date and is waiting for veterinary review. Please check with your vet before acting on it. About our articles

Cognitive Dysfunction--Alzheimer's in Animals
Sometimes older dogs get confused, maybe soil the rug or lose their way in the house. It's perfectly natural.

Or is it?

In the past ten years, veterinarians have come to realize that severe cognitive (or thinking-related) problems are no more normal in older dogs than they are in aging people. While older dogs may move a bit more slowly and get a little gray around the muzzle, they shouldn't experience a complete change in personality. A dog that suddenly seems confused, distant, or lost may be showing signs of cognitive dysfunction.

Cognitive Dysfunction Syndrome (or CDS) is a degeneration of the brain and the nervous system in dogs, roughly comparable to Alzheimer's disease in people. Like Alzheimer's, it is caused by physical changes in the brain and brain chemicals, and it is not a part of normal aging. It results in a deterioration of cognitive abilities, causing behavioral changes that can disrupt the lives of pets and the families that care for them. An ongoing study performed at the University of California-Berkeley has shown that 62 percent of dogs between ages 11 and 16 demonstrate one or more signs of CDS, and the percentage goes up as dogs get older.

The symptoms
So how can you tell if a dog is showing signs of CDS or if she's just getting older? Watch for her to start showing some of the following behaviors:

  • Withdrawing from interaction with the family
  •  Soliciting less petting and attention
  •  Staring at walls or into space
  •  Sleeping more during the day
  •  Sleeping less during the night
  •  House soiling
  •  Difficulty learning new tasks, commands, or routes
  •  Pacing or wandering aimlessly
  •  Frequent trembling or shaking
  •  Ignoring known commands
  •  Becoming lost in familiar places like the home or yard
  •  Getting "stuck" in familiar places, like in corners or behind furniture
  •  Having trouble finding the door or standing at the hinge side of the door
  •  Not responding to name
  •  Decreased activity
  •  Not recognizing family members or other familiar people
If you see these behaviors in your pup, the good news is that you don't just have to accept them. Tell your veterinarian--she may be able to help.

If she suspects CDS, your veterinarian can take a thorough behavior and medical history of your dog. She can also perform a physical and neurological exam and blood and urine tests to rule out other conditions that could cause these symptoms, such as hypothyroidism, kidney problems, arthritis, and hearing and vision loss. Once she's ruled out any underlying diseases, you can discuss treatment.

Unfortunately, there is no cure for CDS, but there is increasing hope. There is now a prescription drug available to treat dogs with CDS in the US (two are available in Europe). It works by increasing the amount of dopamine in the dog's brain. Dopamine is a neurotransmitter that the brain needs to function normally; an increased amount of dopamine can improve brain function. Though it doesn't work in all dogs, the drug can help many dogs with CDS think more clearly, remember more, return to their interactions with family, and enjoy a higher quality of life in their elderly years. Your veterinarian can help you decide whether a prescription is the right thing for your dog.

Veterinarians have not yet determined whether CDS is a factor in aging cats. There are a large number of conditions that can affect older cats, and there is currently no way to distinguish CDS from these conditions. There are no prescriptions approved for treating CDS in cats, but this may be a field that will develop in the future.

For more information about senior pets, see Senior Pet Care