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Sundowning in Dogs

Sundowning in Dogs

By Sarah Bennett · Last updated September 29, 2026 · 9 min read

Is this sundowning in dogs, or a night that belongs on another page? Months of evenings that fall apart after dusk are one clock. A tight belly, dry retching, or collapse that started tonight is another.

If the hard hours are already most of her life, that week is on how to know when it's time to put your dog down. If you are still sorting among pain, urine, vision, and cognitive change, the broader night-pacing list is on dog pacing at night in old age. This page is the dusk pattern, after those two sorts.

What it looks like Which clock
Tight belly, unproductive retching, heavy drool, started tonight Bloat. Call now
Circling, head tilt, eyes flicking, started without warning Vestibular disease
Months of evenings after dusk, still glad to see you in daylight This page, after a vet looks for copies
Hard hours already most of her days, and getting longer The when-to-put week

Dog sundowning at night, in the sense this page uses, is that third row.

Is this tonight, or months of evenings?

Sundowning in dogs that belongs here has been building. Cornell's dementia page puts it plainly: "Most signs of cognitive difficulty have been slowly building up".

A night that started in the last hour is a different problem even when she is also pacing. Cornell's bloat list includes "Non-productive retching or attempting to vomit with no production", a bloated or painful abdomen, excessive drooling, and restlessness. Those signs share a hallway with evening pacing. They do not wait for morning. The full picture is on bloat in senior dogs.

Cornell also splits a sudden balance crash from cognitive decline. "Vestibular syndrome is often confused with cognitive dysfunction syndrome, but it is actually a sudden-onset balance issue". "It appears without warning", with circling or a head tilt, or a dog who cannot stand. They describe eyes that move in a rapid, repetitive way, and they name that nystagmus. That night is old dog vestibular disease.

Stay on this page when the evenings have been getting harder for weeks or months, and daylight still has her in it.

Has a vet looked for the copies?

Sundowning dementia in dogs is a pattern inside canine cognitive dysfunction. The diagnosis waits for the workup. The Anipryl label says "The diagnosis of CDS in dogs is a diagnosis of exclusion, based on thorough behavioral and medical histories, in conjunction with appropriate diagnostic work-up and testing".

AAHA's 2023 senior-care guidelines say the same workup in clinic language: "Cognitive dysfunction may be a diagnosis of exclusion". "A thorough history, physical examination, neurological examination, biochemical evaluation, and urinalysis are integral to ensure these animals do not have other underlying disease causing similar clinical signs". They name pain and organ dysfunction among the lookalikes, along with disease inside the skull.

Cornell's house-soiling note is the same idea in one organ: "Start by taking your dog to the veterinarian to rule out bladder infections". Vision and hearing changes can make a familiar room look worse after the lights go down. Those copies are why a months-long evening pattern still starts with an appointment.

The DISHA list of dementia signs lives on dog dementia symptoms. Staging lives on the four stages of dog dementia. This page does not score her.

What Cornell calls sun-downer syndrome

How to help a dog with sundowning starts with what the night actually is. Cornell files the pattern under sleep and wake, and says "This is often the first sign that families notice". "Your senior dog is now up and walking around in the middle of the night". AAHA's dog list puts the same cluster first among common signs: "daytime sleeping and nighttime restlessness, decreased interaction, disorientation at home, and anxiety".

On that same Cornell page they call the night irritability sun-downer syndrome. The practical list is small.

"Many aging dogs develop a habit called the “midnight walks” that causes them to roam throughout the house at night. Add nightlights so they can see clearly and are less likely to get stuck". "Don’t move dog beds or furniture. Keep food and water bowls in the same location". Older dogs, they write, do better with a predictable routine.

An extra walk right before bed is limited to some dogs: "For some dogs, going for an extra walk right before bedtime can wear them out, leading to longer, deeper sleep".

"Melatonin helps some dogs, but there aren’t a lot of studies to confirm its effects. Discuss this option with your veterinarian before using it". Human sleep gummies are the wrong drawer. The FDA's xylitol list includes "Dietary supplements (like fiber gummies and sleep aids)". "XYLITOL poisoning can KILL your dog".

Diets and MCT oil are a separate page: MCT oil for dogs with dementia. Cornell's own line on antioxidants, omega-3s, and MCTs is that there are few studies and anecdotal evidence is accumulating. Ask the vet before you add a bottle.

What to ask the vet for

Canine sundowning treatment that comes in a tablet is a prescription. "Anipryl tablets are indicated for the control of clinical signs associated with canine cognitive dysfunction syndrome (CDS)". AAHA writes that "selegiline, a selective irreversible monoamine oxidase B inhibitor, is the only drug labeled for use for canine cognitive dysfunction". The veterinarian sets the dose. The label prefers morning.

Cornell reports what owners have said, not a trial of their own: "Some owners may notice improvement in three weeks or less, but many dogs can take six weeks before showing changes. Many owners have said that this medication helps with sun-downer syndrome (worsening symptoms and irritability that occurs at night), as well as night-walking symptoms".

The label's trial language is narrower and still useful. "After 4 weeks of treatment, dogs treated with Anipryl showed significant improvement when compared to placebo-treated controls in sleeping patterns, house-training, and activity level. Some dogs showed increased improvement up to 3 months, however, onset, duration and magnitude of response varied with individual dogs". AAHA summarizes effectiveness as "Selegiline is effective in up to 70% of dogs with cognitive dysfunction". The same paragraph is the warning: "Toxicity can occur if selegiline is used in conjunction with other antidepressants, narcotics, phenylpropanolamine, or monoamine oxidase inhibitors". Bring the current bottle list to the visit.

AAHA also notes shorter-acting anxiety medicines the task force prefers for speed and clearance. Those are the vet's call for the evening hours, alongside pain control, after the exclusion workup.

When the evenings are most of her life

If daylight still has her, and the nights are the part that is stretching, stay in the appointment and the Cornell list above. If the hard hours are already most of her week and still lengthening, take that week to the quality of life scale and to how to know when it's time to put your dog down. Those pages are for the majority of the day, including the days with no single collapse.

The name of the evenings matters less than which clock you are on.

Sundowning in Dogs Frequently Asked Questions

Can sundowning in dogs be cured? Canine cognitive dysfunction is progressive. The evenings can still be made more livable.

How do I know if this is sundowning in dogs? Sort the clock first. Sundowning in dogs, here, is months of confusion, pacing, or vocalizing that worsen after dusk, in a dog who still has daylight hours that look like her. Cornell says that sleep-wake change is often the first thing families notice, and that most cognitive signs have been slowly building. A tight belly, unproductive retching, or collapse that started tonight is bloat. Circling, a head tilt, and flickering eyes that appeared without warning is vestibular disease. Even the months-long pattern is still an exclusion diagnosis: the Anipryl label and AAHA both say other disease has to be looked for, including pain, urine, and organ trouble. Take the week to the vet. Do not name it from this page alone.

Does melatonin help sundowning in dogs? Cornell's line is that melatonin helps some dogs, and that there are not a lot of studies to confirm its effects. Ask your vet before you use it. Do not use a human sleep gummy. The FDA lists fiber gummies and sleep aids among xylitol products, and xylitol poisoning can kill a dog.

Is evening pacing bloat? Pacing happens in both. Bloat adds unproductive retching, a bloated or painful abdomen, or heavy drool, and it starts tonight. Cornell's list and our bloat page are the ones to use if those signs are in the room.

Should I start Anipryl tonight? No. It is a prescription. The vet sets the dose after the exclusion workup, and AAHA warns about mixing it with several other drug classes.

Sources

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About the authors

Sarah Bennett writes about senior dog care as an owner and researcher, not as a veterinarian. This guide is reported from Cornell's senior-dementia page, AAHA's 2023 cognitive-dysfunction chapter, and the Anipryl label. Lucy, a Border Collie, is the dog in the household that the byline describes.

Leo Bennett is the co-author of Senior Dog Daily and Sarah's husband. The pair share research and writing duties on the site.

Sarah and Leo Bennett are pen names. Senior Dog Daily is written and checked by a small editorial team; see About.