Can dogs really get a form of Alzheimer's?

Dogs develop a closely related condition called canine cognitive dysfunction (CCD), sometimes called canine dementia or, informally, canine Alzheimer's. As dogs age, they can show confusion, disorientation, anxiety, and late-day agitation that mirror human dementia. CCD shares some of the same brain changes, including beta-amyloid buildup.

What is sundowning in dogs?

Sundowning is a pattern where a dog becomes more confused, restless, and agitated as daylight fades in the late afternoon or evening. In a dog with CCD, falling light can trigger barking, pacing, and inconsolability. It's one expression of the disrupted sleep-wake cycle that defines the condition.

How common is canine cognitive dysfunction?

Far more common than most owners think, and badly underdiagnosed. Studies of advanced cognitive dysfunction found it in about 8 percent of dogs aged 8 to 11, rising to roughly 19 percent at 11 to 13, 45 percent at 13 to 15, and 67 percent at 15 to 17. Many cases are missed because owners assume the changes are just normal aging.

How do vets diagnose it?

There's no single test; diagnosis is clinical, ruling out other illness and scoring behavior changes. Vets use the acronym DISHAA: Disorientation, altered Interactions, Sleep-wake disruption, House-soiling, altered Activity, and Anxiety. It expands the older D.I.S.H. checklist by adding activity and anxiety.

Is there a treatment?

There's no cure, but options can meaningfully help. Selegiline (Anipryl) is the only FDA-approved drug for CCD. Vets also use environmental light, diets and supplements aimed at brain aging, anti-anxiety medication for distress, and a consistent routine. A veterinarian should guide any treatment plan.

Illness & Conditions

Your Senior Dog Falls Apart at Dusk. There's a Name for It, and a Plan

When the light fades, some old dogs grow frightened, restless, and inconsolable. It's called sundowning, a sign of canine cognitive dysfunction that's far more common, and more treatable, than most owners realize. Here's how to recognize it and what helps.

By Dr. Mara Chen, Senior Veterinary Editor

June 9, 2026 · 7 min read

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As the days shorten and the light drops earlier and earlier, four o’clock, then three, some old dogs come undone. A senior dog who was fine all day plants himself on the floor as dusk falls and starts a frantic, inconsolable barking, or paces, or licks at his paws until they’re raw. Owners describe it as a switch flipping with the daylight. It can be bewildering and heartbreaking, and the first instinct is usually to assume the dog is in pain, or being difficult, or simply “getting old.”

There’s a name for what’s happening, and recognizing it is the difference between a baffling nightly ordeal and a manageable condition. It’s called sundowning, and in dogs it’s a hallmark of canine cognitive dysfunction. The encouraging part, and the reason this is worth understanding rather than dreading, is that it’s both more common and more treatable than most owners are ever told.

Yes, dogs get a version of Alzheimer’s

Canine cognitive dysfunction (CCD), also called canine dementia, is the closest canine parallel to human Alzheimer’s, and the resemblance isn’t just behavioral. Aging dog brains accumulate some of the same beta-amyloid changes seen in human Alzheimer’s, and the result can mirror it: confusion, disorientation, disrupted sleep, anxiety, and the late-day agitation that defines sundowning. Human Alzheimer’s patients are well documented to grow more confused and agitated in the late afternoon and early evening; in a dog with CCD, the very same fading light can set off barking, pacing, and a panic the dog can’t be soothed out of.

Put plainly: if your senior dog turns into a different, frightened animal at dusk, you’re likely not imagining a connection to dementia. You’re seeing one.

How common it really is (and why you’ve probably never heard the numbers)

This is the part that reframes everything, and it’s net-new ground the old “does my dog have Alzheimer’s?” framing never covered. CCD isn’t a rare curiosity. Research on advanced cognitive dysfunction found it in roughly:

8 percent of dogs aged 8 to under 11,
19 percent at 11 to under 13,
45 percent at 13 to under 15, and
67 percent at 15 to under 17.

In other words, by the time a dog reaches its mid-teens, the odds of meaningful cognitive decline are better than even. And yet the condition is consistently underdiagnosed, for one stubborn reason: owners, and sometimes vets, write the early signs off as “just getting old.” A dog who sleeps more, seems vaguer, or has the occasional accident gets a shrug instead of a workup. The true rate is almost certainly higher than even those numbers suggest.

“The single biggest barrier isn’t the science, it’s the assumption that confusion is a normal part of aging,” says Dr. Priya Nair, a veterinarian who works with senior dogs. “It often isn’t. When an owner can name what they’re seeing, we can usually do something about it. Sundowning is one of the clearest tells, because it’s tied so neatly to a trigger: the light going down.”

How vets actually spot it: DISHAA

There’s no blood test for CCD. Diagnosis is clinical, your vet rules out other illnesses that can mimic it (pain, vision or hearing loss, thyroid problems, urinary issues) and then scores the behavioral pattern. The framework most vets use is the acronym DISHAA, an expansion of the older D.I.S.H. checklist:

D, Disorientation: getting stuck behind furniture, going to the wrong side of a door, staring at walls, seeming lost in familiar rooms.
I, altered Interactions: less responsive to people and cues, or unusually clingy or withdrawn.
S, Sleep-wake disruption: sleeping more by day and less at night, with pacing and restlessness after dark, the bucket sundowning falls into.
H, House-soiling: accidents in a previously reliable dog.
A, altered Activity: aimless wandering or repetitive behaviors, or a drop in purposeful activity like play.
A, Anxiety: new or worsening fearfulness, especially as evening comes on.

The two extra letters matter. The older D.I.S.H. version captured the basics but missed the activity changes and the anxiety that are often the most distressing parts for both dog and owner, and the most useful to treat. If several of these are creeping in and clustering at dusk, that’s your cue to book a veterinary visit rather than to wait and see.

“Sundowning makes the whole picture more recognizable,” says Dr. Ravi Mehta, a veterinarian who focuses on geriatric care. “We used to file the sleep problems under one vague heading that covered the whole night. Anchoring them to the moment the light changes gives owners something concrete to watch for: as evening arrives, a subset of dogs with cognitive dysfunction lose their bearings and grow agitated, and that agitation can build into the frantic pacing and barking that wear a household down. It’s a very useful addition to how we think about the condition.”

What actually helps

Here’s the honest framing your vet will give you: there’s no cure, the brain runs on too many neurotransmitters for any single fix to resolve everything, and results vary a lot from dog to dog. But “no cure” is a long way from “nothing to do.” A combination approach genuinely helps many dogs, and it splits into managing the symptoms and treating the underlying decline.

Managing the sundowning itself:

Light the space. Flooding the area with light at dusk can erase the frightening shadows that seem to trigger the panic, though this only helps dogs whose vision is still intact.
Lock down the routine. Consistent meal, walk, and bedtimes give a disoriented brain scaffolding. Predictability is calming.
Address the anxiety. For dogs in real distress, a vet may prescribe anti-anxiety medication. This is a conversation for your veterinarian, not a self-serve decision, dosing and drug choice depend on your specific dog and its other conditions.

Treating the underlying condition:

Selegiline (brand name Anipryl) is currently the only FDA-approved medication for canine cognitive dysfunction. It’s a monoamine oxidase inhibitor that boosts dopamine and other neurotransmitters in the brain. In clinical trials, dogs on selegiline showed real improvement over placebo in sleep, house-training, and activity after about four weeks. It doesn’t work for everyone, roughly a third of dogs respond dramatically, a third improve meaningfully, and a third don’t respond, and benefit, when it comes, tends to be measured over months. Surveys show most vets rate current treatments as only slightly to moderately effective, yet a large majority still recommend them, because partial help in a distressing condition is well worth having.
Diet and supplements aimed at brain aging (think antioxidant-rich therapeutic diets and omega-3s) are commonly recommended as part of the plan, with your vet guiding the specifics.

A word of caution that bears repeating in any medication discussion: every drug, supplement, and dose here belongs in a conversation with your veterinarian, not in a DIY plan off the internet. Selegiline in particular interacts dangerously with certain other medications. Use this article to recognize what you’re seeing and to walk into that appointment knowing the right questions, not as a substitute for the appointment.

If your dog is the one going to pieces at dusk, the most important thing to take from all this is that you’re not powerless and your dog isn’t simply “old and difficult.” You’re looking at a real, named, common condition with a real, if imperfect, set of tools to ease it. Naming it is the first step. The plan follows.

This article touches on a medical condition and prescription medication and is for general education only. Always consult your veterinarian before starting, stopping, or changing any treatment.