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7 Signs of Sundowners Syndrome in Dogs (2023)

Medically reviewed by Erica Irish, DVM on April 27, 2023

Sundowners syndrome in dogs is the result of canine cognitive dysfunction syndrome (CDS), or canine dementia.

It’s not always easy to recognize, especially if there is a gradual change in behavior.

Mobility and memory problems can have a number of medical causes. The important thing to understand is that any changes in your dog’s behavior or personality should be addressed by a licensed veterinarian.

Dogs, like people, are unique beings.

The signs of sundowners can vary from dog to dog. In order to make a definitive diagnosis, the veterinarian will want to rule out medical causes.

This post is designed to help you understand sundowners syndrome and what it might look like for your dog. We’ll explain the acronym DISHAAL, and how it can help you recognize signs of dementia in your dog.

Finally, we’ll take you through some of the best ways to manage your dog’s symptoms while providing soothing care.

A Short Explanation of Sundowners Syndrome in Dogs

The term “sundowners syndrome” reflects the time of day when clinical signs are most evident. Signs of sundowners syndrome can happen at any time of the day, but it appears to worsen at night.

One reason for this may have something to do with a disruption of the dog’s biological clock.

A drop in melatonin

Dogs with dementia undergo structural changes in the brain that ultimately lead to a drop in melatonin levels.

Melatonin, as you may know, is a hormone that regulates the circadian rhythm. The circadian rhythm is defined as “the natural cycle of physical, mental, and behavior changes that the body goes through in a 24-hour cycle”.

In a healthy dog (or person), the body releases more melatonin when it senses less light. It’s what helps regulate the sleep-wake cycle.

Dogs with cognitive dysfunction may not be able to produce enough melatonin to make them sleepy. Low melatonin can also lead to anxiety and other health issues.

Brain inflammation and irreversible loss of nerve cells

Unfortunately, dogs with dementia seem to show similar signs of cognitive dysfunction as people with Alzheimer’s disease. As canine dementia worsens, proteins called beta-amyloid build up in the brain’s tissues.

This build-up of proteins in the brain forms plaques that lead to brain inflammation and the loss of nerve cells.

The slow build-up of cognitive dysfunction

Clinical signs of cognitive dysfunction can creep up slowly. This can make it difficult to identify in its early stages. As with any health issue, the earlier the signs are spotted, the easier it can be to manage.

Unfortunately, you can’t stop aging and there’s no cure for canine dementia. If you have a senior dog, make sure to report any unusual behavior to your veterinarian as soon as possible.

According to, clinical signs of dementia are found in 50% of dogs over the age of 11.

signs of sundowners syndrome in dogs

Diagnosing Cognitive Dysfunction Syndrome in Dogs

Cognitive dysfunction syndrome (CDS) in dogs is also known as canine dementia or doggy dementia. Some people refer to it as the equivalent of having Alzheimer’s disease.

Diagnosis is more about eliminating the possibility of other medical conditions like kidney disease.

Vestibular syndrome can be confused for CDS in dogs because of the signs. Dogs with this condition will appear suddenly off-balance.

Pain can also mimic signs of cognitive dysfunction. For example, pain can cause restlessness, vocalization, and sudden anxiety in dogs.

It’s also possible for senior dogs to have undiagnosed medical conditions along with cognitive decline.

The veterinarian will likely perform a physical examination, order blood tests, urine tests, etc.

Treatment Options for Dogs with Sundowners Syndrome

Treatment options for CDS can help slow the progression but do not provide a cure. The best outcome is to relieve as many symptoms as possible while improving your dog’s quality of life.

Dietary Supplements

 Consider switching to a diet designed especially for senior dogs dealing with cognitive dysfunction.

The best ones to try and options for including antioxidants, omega-3 fatty acids, or medium-chain triglycerides in your dog’s diet can be discussed with your veterinarian.

Although there are few studies on the use of these supplements in senior dogs, anecdotal evidence suggests they are generally safe.(“Senior Dog Dementia”)

Ask your veterinarian about these supplements before administering to your dog:


Dietary Changes

There are plenty of dog food brands on the market designed for senior dogs. However, they may not address certain health issues like CDS or sundowners syndrome.

If your dog has been diagnosed with cognitive dysfunction, you’ll want to purchase dog food rich in antioxidants, healthy fats, and Omega-3 or Omega-6 fatty acids. These are thought to protect and promote healthy brain cells.

Talk to your veterinarian about a prescription diet.

Studies suggest that senior dogs fed an antioxidant-fortified diet showed significant improvement in learning and their memory of learned tasks. High levels of the right antioxidants can slow the rate of cognitive decline in older dogs.

The following are two examples of prescription diets designed to help slow cognitive decline in dogs diagnosed with sundowner syndrome:

Hill’s Prescription Diet b/d

Purina Pro Plan Veterinary Diets NC


In order to help improve your dog’s cognitive function, medications like selegiline (brand name Anipryl) may be prescribed. Anipryl is a first-generation anti-depressant known as an MAO inhibitor.

Selegiline increases dopamine levels in the brain. This process helps to reverse changes in the brain caused by CDS.

Noticeable improvement can take three weeks or more.

If you have a new veterinarian or your veterinarian isn’t aware that your dog is on (or has recently taken) prescription medications or supplements (including over-the-counter), make sure to tell them.

MAO inhibitors and other prescriptions could cause serious drug interactions.

It’s not unusual for geriatric dogs to develop anxiety. They may suddenly react to loud noises or develop repetitive behaviors like constantly licking a paw. In this case, the veterinarian may suggest anti-anxiety medications and anxiety supplements.

Cognitive & Environmental Enrichment

There’s a lot of focus on improving and retaining memory, especially in older adults. The reason is because the more you use your brain, the stronger it becomes. The same is true for old dogs.

It’s like a muscle. You’ve probably heard the “use it or lose it” saying.

While dogs can’t download memory apps on their phones, they can engage in activities that will help stimulate their brains.

Exposing your dog to a variety of sights, sounds, smells, and textures can help with mental stimulation.

Some ideas include:

  • Take a different route for your regular walk. Your dog will benefit from the new sights and smells.
  • Smear a bit of peanut butter or wet dog food on a textured lick mat.
  • Talk to your dog and encourage family members to playfully interact. Senior dogs with CDS may startle easily so be gentle and cautious. Monitored social interactions are still important for older dogs.
  • Hide treats in places where your dog will be safe to wander around. Put a gate around stairways and block or close doors to prevent your senior dog from getting hurt.
  • Maintain a regular routine.

Clinical Signs of Canine Dementia

DISHAAL is an acronym used to describe the signs of cognitive dysfunction syndrome in dogs. It stands for:

  • Disorientation
  • Abnormal interactions
  • Sleep/wake cycle disturbance
  • House soiling
  • Activity Changes
  • Anxiety
  • Learning or memory changes

Sundowners syndrome in dogs usually begins in the late afternoon or early evening as the sun goes down.

Clinical Signs of Sundowners Syndrome in Dogs

If your dog has cognitive dysfunction (dementia), he or she may experience the following signs of sundowners syndrome:

1. General Confusion

You know your dog better than anybody else. Cognitive dysfunction in dogs tends to cause some confusion during the day, but when the sun goes down a whole new phenomena develops.

Dogs with sundowner syndrome may whine or cry at night, pant heavily, pace the floor in the middle of the night, or suddenly appear afraid for no apparent reason.

2. Anxiety

Fear in dogs can occur for all kinds of reasons. It’s not necessarily a sign of cognitive dysfunction or sundowners syndrome. However, if you notice an increase in anxiety as your dog ages, it might be time for a wellness check.

Sundowner’s syndrome in dogs is a progressive disease.

3. Nighttime Distress

A lot of symptoms like using the bathroom in the house, bumping into walls, getting stuck in corners, and suddenly losing interest in previously fun things can happen day or night.

These could be signs of cognitive dysfunction in dogs, but they could also point to things like vision loss or pain.

Sundowners syndrome in dogs refers to unusual behaviour that occurs as night approaches.

The gradual loss of cognitive function is terrifying. The dog doesn’t know what’s happening. All he/she knows is that it’s dark and he can’t recognize familiar things, may not recognize the room where his/her owner’s sleep, etc.

As a result of this disorientation, the dog will become very scared and may pace, whine, howl, or cry.

4. Aggression and Irritability

It could be said that all of the signs noted above are directly related to the fear and confusion a dog with dementia feels.

Anger and hostility can also show itself in the wee hours of the evening. Your otherwise happy dog may suddenly bark, snarl, or growl.

Other animals in the house should be kept apart from the dog with dementia for safety reasons.

5. Destruction of Property

Fear and agitation can lead to obsessive chewing and destruction of shoes, books, wallets, etc. This process might even remind you of the puppy stage when your dog had to be crated temporarily to avoid chaos in the house.

6. Separation Anxiety

Dogs with sundowners syndrome don’t understand what’s happening to them. As a result, they can get really clingy. Your otherwise independent dog may suddenly want to be right by your side all the time.

You may notice an entire personality change. Thunder shirts are a popular product for dogs with anxiety disorders. They’re a good choice if you’d like to try something other than prescription medication.

Other ways to help ease your dog’s anxiety could include playing soothing background music or trying a calming supplement like Rescue Remedy.

Always check with your veterinarian before administering over-the-counter supplements.

7. House Soiling

Part of dementia is the gradual lose of memory. In the advanced stages of dementia, your dog may not remember that he or she is suppose to go potty outside. All memory of house training could be lost.

In fact, their bodies may not remember how to hold their bladder or bowels at all. This is known as urinary incontinence and fecal incontinence.

At What Age is My Dog Considered Senior

Defining the point at which a dog is considered senior depends on a variety of things. Large dogs tend to age faster than smaller dogs. For example, a chihuahua might be considered to be a senior at 10 years of age.

On the other hand, a giant breed like the Great Dane might be considered senior at the age of 5.

Signs that your dog is getting old include:

  • Joint stiffness or pain
  • Vision problems
  • More lumps and bumps
  • Difficulty hearing
  • Vision loss (cloudy eyes, cataracts)
  • Weight changes
  • Less active
  • Going grey

Rather than focusing on years of age, dog owners can better serve their pets by paying attention to potential health problems.

Changes are inevitable as a dog ages. Pet parents may notice a chance in sleep patterns, memory loss, or symptoms of dementia.

The important thing is to pay attention to the subtle changes that occur and keep regular appointments with the veterinarian for wellness checks.


At the end of the day, we want our dogs to have a great quality of life, especially in their golden years.

Whether your dog has sundowners syndrome or some other illness that is affecting him or her, remember that there are still a lot of things you can do to keep your dog happy.

As your dog reaches old age, watch for behavioral changes and other signs that something might not be right.

Exercise, patience, supplements, and follow-up visits with the veterinarian are all highly recommended treatments for sundowners syndrome in dogs.

I wish you luck and ask that you contact me at: with tales of your dog’s triumphs.

Thank you for reading this post. I hope you were able to get useful information.

Works Cited

Fantegrossi, Dina. “Sundowners Syndrome in Dogs: Is Your Senior Dog Suffering at Night?”, 8 May 2019,

“Senior Dog Dementia.” Cornell University College of Veterinary Medicine, 3 Oct. 2022,

“Your Brain Is Like a Muscle: Use It and Make It Strong.” Your Brain Is Like a Muscle: Use It and Make It Strong · Frontiers for Young Minds, 24 Apr. 2014,

Center, Burlington Veterinary. “Enrichment Activities for Pets – Burlington Veterinary Center.” Burlington Veterinary Center, 13 Oct. 2021,

“Nutrition for Dogs With Cognitive Dysfunction Syndrome (CDS) | VCA Animal Hospitals.” Vca, Accessed 27 Apr. 2023.

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