Sundowners in Dogs: Cognitive Dysfunction Syndrome

Also known as old dog senility—a degenerative disorder in senior dogs.
By Shea Cox DVM, January 2013, Updated November 2020
sundowners in dogs

Cognitive Dysfunction Syndrome, also referred to as “sundowner syndrome, ” “old dog senility,” or dementia in dogs is a common syndrome that is categorized as a slow, degenerative and progressive disorder in our aging pets.

As a dog succumbs to the process it leads to changes in awareness, decreased responsiveness to normal surroundings, and potentially increased signs of anxiety that usually worsen in the night hours.

Symptoms

Many typical behavior changes seen in senior dogs like confusion, wandering, getting stuck, barking, obsessive licking are symptoms of this disorder. The symptoms of sundowner syndrome can be lumped into a few general categories.

Disorientation

With sundowner syndrome, dogs may experience disorientation such as going to the wrong side of the door to be let outside or getting lost in familiar environments.

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Altered interactions

Many dogs with sundowners may experience increased irritability, anxiety or agitation due to a loss in the ability to communicate properly with other animals.

Alterations in sleep-wake cycles

This is most often observed as increased restlessness (especially at night) and/or vocalizations that are seemingly directed at nothing in particular; as the disease progresses, you may continue to notice worsening of these signs and begin to see your pet aimlessly wandering the house with compulsive behaviors such as barking at the wall for no apparent reason or excessive grooming.

Learned Behaviors May Change

You may notice your dog becoming less adept at its normal tasks, such as house training or responding appropriately to previously learned commands; you may also notice that your pet has difficulty recognizing and reacting to its familiar family members.

Slow Progression

The symptoms of sundowners in dogs generally begin very gradually, so much so, that many pet parents fail to recognize the early stages of the disease and often attribute their pets subtle alterations in behavior to “simply getting older.”

A recent study at the University of California School of Veterinary Medicine demonstrated just how common these observations are: out of 69 dogs participating, 32% of the 11-year old dogs were affected by sundowner syndrome and 100% of the dogs 16 years of age older were affected.

The exact reason for this change in our geriatric pets is unknown, but it is thought that the body’s normal degenerative and age-related changes contribute to the cognitive dysfunction. These changes include central nervous system deterioration, oxidative stress, accumulation of free radicals, and cell death. Signs are unfortunately progressive and treatment is aimed at prevention and/or slowing the progression of disease for which lifelong therapy is required once diagnosed.

Treatment

Treatment is the utilization of a multi-modal approach to managing signs, meaning, a combination of synergistic therapies that are based on the severity of the clinical signs. Selegiline is a prescription medication that is used to help control more severe symptoms, and it is thought to improve transmission of brain chemicals (dopamine) as well as have protective effects on the brain’s nerve cells.

There has also been the development of commercial and prescription “senior diets” that have demonstrated improvements in cognitive function, such as Hill’s b/d ("brain diet").

Natural supplements have shown promise in managing signs and slowing the course of disease by reducing the neurological damage caused by free radicals. They include antioxidants (vitamins C and E, selenium, flavonoids), gingko bilboa, Omega-3 fatty acids, and medium chain triglycerides to name a few.

Pheromone therapy and melatonin may ease anxiety and promote a feeling of well being for dogs that experience increased anxiety at night.

And finally, environmental enrichment such as brisk brushing sessions, massage therapy, interactive toys, and stimulating walks is thought to be an important cornerstone in slowing the progression by stimulating brain activity. Maintaining a stimulating environment, and engaging in as much activity as is practical for your pet’s age and health, may help prevent or delay the onset of cognitive decline as your pet moves into its golden years.

I will end with one of my favorite veterinary mantras, which is: “Old age is not a disease” (for which I am personally more thankful for each day), and with proper care, our senior “babies” can go on experiencing a good quality of life as cognitive changes develop.

Photo by Carlos Mossmann

Shea Cox earned a veterinary medical degree from Michigan State University in 2001 and has been practicing emergency and critical care medicine since. In 2006, she joined PETS Referral Center. In her spare time, she loves to paint, wield her green thumb and cook up a storm. She shares her days with the three loves of her life: her husband Scott and their two Doberman.