Canine Cognitive Dysfunction (CCD): A Clinical Guide for Dog Owners

The short answer

Canine cognitive dysfunction (CCD), often called dog dementia, is a progressive brain condition of older dogs that changes thinking, memory and behavior beyond normal aging. Early changes are subtle; as CCD advances, they disrupt more of daily life. Estimates run from about 14 to 35 percent of dogs over 8. There’s no single test. Your vet diagnoses it from slowly worsening signs, scored on a questionnaire, after looking for and treating look-alikes such as pain, hearing loss or other illness. There’s no cure, and its pace varies widely between dogs.

If your vet suspects CCD: ask which behaviors concern them, which other conditions need checking first, and when to repeat the same behavior questionnaire. The diagnosis section below walks through each step.

On this page: Signs, Diagnosis, Other possible causes, Treatment, Progression, Questions for your vet.

This guide covers what your vet is doing and why: the signs vets score, the tests that rule out look-alikes, when a neurologist helps, and what to bring to the appointment. It follows diagnostic and monitoring recommendations proposed by an international veterinary working group in JAVMA, the Journal of the American Veterinary Medical Association. They were published online on December 24, 2025, and appear in the April 1, 2026 issue (Olby 2026). The group presents them as a starting point, to be revised as research advances (Olby 2026).

CCD, CDS, CCDS: what the names mean

If your vet said “cognitive dysfunction” or wrote CCD or CDS in your dog’s record, they meant the condition this site covers in plain language as dog dementia. Veterinary papers use these names for the same condition (Dewey 2019; Olby 2026).

Name	Where you’ll see it
Canine cognitive dysfunction (CCD)	Veterinary records and research papers (Dewey 2019)
Cognitive dysfunction syndrome (CDS)	The FDA approval for the drug selegiline (FDA 1998)
Canine cognitive dysfunction syndrome (CCDS)	The 2026 JAVMA working-group guidelines, which propose it as an umbrella term for canine dementia (Olby 2026)
Mild cognitive impairment (MCI)	Some studies, for dogs with milder changes that fall short of CCD (Schutt 2015)
Dog dementia, canine dementia	Everyday words for CCD
Cognitive decline	A general description of thinking changes with age, not a diagnosis by itself

The human comparison you’ll hear most is Alzheimer’s disease. It’s a useful comparison but not an exact one; the FAQ below explains the difference.

How common CCD is, and when it starts

CCD is common in older dogs, and much of it goes undiagnosed. Published estimates vary from study to study, from about 14 to 35 percent of dogs over 8 (Dewey 2019). In one owner survey of 497 dogs aged 8 and older, 14.2 percent met questionnaire criteria for CCD, and the authors concluded that most such dogs never receive a formal diagnosis (Salvin 2010).

CCD gets much more common as dogs age. In the same survey, prevalence rose exponentially with age (Salvin 2010). In a study of 180 dogs aged 11 to 16, owners’ answers showed impairment in at least one category of signs in 28 percent of 11- and 12-year-olds and 68 percent of 15- and 16-year-olds (Neilson 2001). That measures behavior changes, not confirmed CCD diagnoses.

Most of the studies cited here look at dogs 8 and older, and Cornell’s canine health center says dogs may start to develop CCD at around 9 or older (Cornell). The 2026 guidelines start earlier: a short behavior check at least once a year for every dog from age 7, so changes are noticed early (Olby 2026).

Mild CCD is easy to miss. The changes are subtle and infrequent, the dog still manages normal daily life, and owners often put them down to old age, so the guidelines warn they can go unnoticed unless someone screens for them (Olby 2026). Your observations are where the diagnosis starts. For more numbers, see our dog dementia statistics.

The signs vets look for: DISHAA

Vets group the signs of CCD into six areas under the acronym DISHAA, and the 2026 guidelines use the same six (Olby 2026). The H covers house soiling together with learning and memory. Early on, a dog may show changes in just one area; later, in several (Olby 2026). What counts is change from your dog’s own normal: accidents indoors are a sign only in a dog that was fully house-trained before (Olby 2026).

Area	What it can look like at home
Disorientation	Gets stuck behind furniture or in corners, or has trouble getting around objects; goes to the hinge side (the wrong side) of a door; stares into space or at walls; gets lost in the house or yard; seems not to recognize familiar people
Impaired social interactions	Less interest in greeting you, coming over or being petted; more irritable, fearful or aggressive with people or other pets; or the opposite, more attention-seeking
Sleep disturbances	Restless, pacing or awake at night; barking or whining at night; sleeping more during the day
House soiling, learning and memory	Accidents indoors in a previously house-trained dog, or asking to go out less; slower to learn new things; responds less to familiar cues or their name (hearing loss can look the same); harder to get their attention
Activity changes	Either more activity, such as aimless pacing or wandering and repetitive habits like circling, licking or staring into the air, or less, with less exploring and play
Anxiety and fear	More anxious when apart from you; more fearful of sights or sounds; new fear of places

Table sources: Olby 2026; DISHAA tool; Fast 2013; Dondi 2026 for hearing loss.

These are patterns to tell your vet about, not signs that confirm CCD on their own (Olby 2026).

Not every sign shows up at once. Studies cited in the guidelines suggest that restless nights, less activity during the day and changes in social behavior tend to come first, while house soiling and getting disoriented in space become more common as CCD gets more severe (Olby 2026). You may also see DISHA, an older version of the checklist without the anxiety category (Lobprise 2019).

For more on each sign, see dog dementia symptoms. Our free cognitive assessment walks through these areas in a few minutes and gives you a summary to take to your vet. It’s a screening aid, not a diagnosis.

Normal aging or CCD?

Telling normal aging from early CCD is genuinely hard, and the guidelines say so (Olby 2026). Some slowing down is expected in an older dog. What your vet is looking for is change beyond that, and these are the questions behind the diagnosis (Olby 2026):

Question your vet is asking	What points toward CCD
Is this a decline from your dog’s own normal?	Yes: behavior has slipped from how your dog used to be, in one or more DISHAA areas
Is it a change in thinking and behavior, beyond physical slowing?	Yes: confusion, house-training lapses, night waking or new anxiety, not just slower walks
Is it slowly getting worse?	Yes: CCD creeps on slowly; a sudden change points somewhere else
Does it affect daily life?	Yes, barely at first and much more later
Does a questionnaire score back it up?	Yes: the guidelines ask for an abnormal score on a CCD questionnaire
Is it still there once other problems are treated?	Yes: pain, hearing loss or other illness can explain some changes, so those are treated first to see what’s left

How vets diagnose CCD, step by step

There’s no single test for CCD, and no blood test yet (Olby 2026). The 2026 guidelines describe two levels of certainty (Olby 2026):

• Level 1: your vet builds the diagnosis from the pattern of changes, an abnormal questionnaire score, a physical and neurologic exam, routine lab tests, and a recheck after other medical problems are managed.
• Level 2: a brain MRI adds evidence by showing brain shrinkage (atrophy) and checking for other brain disease, and a spinal fluid test helps rule out other causes. A normal spinal fluid result fits CCD but doesn’t prove it.

Either way, CCD is a diagnosis of exclusion: it’s what remains once other causes have been looked for and managed (Olby 2026).

Step	What happens	Why it matters
1. History and a questionnaire	You describe what has changed and when, and fill in a CCD questionnaire (the guidelines recommend the DISHAA one). Your vet also asks about your dog’s surroundings and every medicine your dog takes.	Level 1 needs slowly worsening signs, a decline from your dog’s previous level, and an abnormal questionnaire score. Questions about other illnesses belong here too.
2. Physical exam, including orthopedic and eye exams and a blood pressure check	A full exam that includes the joints and movement, the eyes and blood pressure	To find other conditions that add to the signs, such as pain or poor vision, so they can be managed. High blood pressure can affect the nervous system (Dondi 2026).
3. Neurologic exam	A hands-on check of the nervous system	In CCD, any changes involve the forebrain broadly rather than one side or one spot, and the cranial nerves, posture reactions and spinal reflexes stay normal. In mild CCD the exam is likely normal.
4. Lab work	A complete blood count (CBC), a chemistry panel and a urine test (urinalysis), plus other tests if needed. A 2026 review also lists thyroid testing as routine (Dondi 2026).	To find treatable conditions that can cause similar behavior changes
5. Manage other conditions, then reassess	Your vet treats or manages anything else that could be adding to the behavior changes, such as pain or another illness, then checks whether the signs persist. The guideline’s flowchart suggests a recheck after about 2 to 4 weeks when no related illness was found or the illness was short-term, and after 4 to 8 weeks when a long-term illness is being managed (Olby 2026); your vet may choose a different schedule	Finding another problem doesn’t rule out CCD. The recheck shows how much of the change it explained.
6. MRI and spinal fluid, when needed (Level 2)	A brain MRI, then a sample of spinal fluid (CSF) taken under anesthesia	Rules out problems such as a stroke, a brain tumor or brain inflammation, and looks for the brain shrinkage seen in CCD. In CCD the spinal fluid should be normal; that helps exclude other causes but doesn’t prove CCD on its own.
7. Rescore over time	The same questionnaire, ideally filled in by the same person each time	How your dog’s score changes says more than any single score

Table source: Olby 2026, all rows, except where Dondi 2026 is named.

The questionnaires vets use

Questionnaires turn what you see at home into a score your vet can track, which matters because a short appointment shows little of how your dog thinks (Olby 2026). The guidelines recommend the DISHAA questionnaire for use in the clinic: it’s the one general-practice vets use most, and it covers all six areas (Olby 2026). Research studies more often use one of two other scales (Olby 2026):

• the Canine Dementia Scale (CADES), a 17-item scale that picks up mild changes better (Madari 2015; Olby 2026);
• the Canine Cognitive Dysfunction Rating scale (CCDR), a 13-item scale that stays steadier over time and is less swayed by the placebo effect (Salvin 2011; Olby 2026).

The Canine Cognitive Assessment Scale is another accepted option (Olby 2026).

A score isn’t like a lab result. It records the pattern you see at home and shows how it changes, and your vet still has to check for medical and neurologic causes (Olby 2026). That’s why the trend matters more than any single score, and why it helps to use the same questionnaire each time, filled in by the same person (Olby 2026).

How often to screen and rescore

The 2026 guidelines set out a schedule (Olby 2026):

• From age 7: a short behavior check at least once a year, which can be a simple senior health form you fill in.
• If that check turns up changes: a full CCD questionnaire, then rescoring every 6 months.
• From age 10: a CCD questionnaire every 6 months for every dog, because the change in your own dog’s score shows where things are heading.

Conditions that can look like CCD

Age brings changes in every body system, and many illnesses can cause behavior changes that look like CCD (Olby 2026). Several are treatable, which is why the workup matters. Finding one doesn’t rule CCD out, though. The two can exist together, so the other problem is treated and your vet watches what changes (Olby 2026).

Looks like CCD	May actually be	Why it matters
Restless nights, pacing, irritability when touched	Pain, most often from osteoarthritis	Pain is a major confounder and can be treated. A dog in pain may also soil the house if posturing or stairs are hard. The guidelines build an orthopedic exam into every CCD workup (Dondi 2026; Olby 2026).
Not responding to you or their name, seeming lost, new anxiety	Vision loss (for example from cataracts) or deafness	Sensory loss can cause disorientation, anxiety and changes in social behavior (Dondi 2026). Owners of dogs with CCD also report it, so both may be present; the workup includes an eye exam (Olby 2026).
Accidents in the house	Urinary tract infection, urinary incontinence, kidney disease, diabetes, Cushing’s disease, or pain that makes reaching the door or posturing hard	Diabetes, Cushing’s disease, kidney disease and bladder inflammation can all lead to accidents, and urinary incontinence is not unusual in older dogs, especially spayed females (Denenberg 2017). Pain can make posturing or stairs hard (Dondi 2026). Blood and urine tests are part of every workup, and some causes need further tests (Olby 2026).
Lethargy, confusion, dullness	Hypothyroidism, chronic kidney disease, or liver disease affecting the brain (hepatic encephalopathy)	These can cause lethargy, mental dullness or confusion (Dondi 2026), and the routine lab work is there to find conditions like these (Olby 2026)
New confusion after a medicine change	A medication side effect	Some drugs, including corticosteroids, benzodiazepines and anticonvulsants, can make these signs worse (Sung 2024). The guidelines ask your vet to review your dog’s medicines as part of the history (Olby 2026).
A head tilt, circling always to one side, weakness or stumbling on one side	A balance-system (vestibular) disorder, which can start outside the brain or inside it; or a stroke, a brain tumor, brain inflammation or another neurologic condition	A head tilt is one of the signs of vestibular disease (Rossmeisl 2010). CCD itself isn’t expected to cause focal or one-sided signs; they suggest another condition, instead of CCD or alongside it (Olby 2026). When such signs point to the brain, the guidelines recommend an MRI (Olby 2026), and a 2026 review flags brain tumors especially when signs start quickly or are focal (Dondi 2026). Pacing in both directions can be part of CCD, and the DISHAA checklist lists repetitive circling as a sign; circling that always goes the same way is what points elsewhere (Olby 2026; DISHAA tool).
A seizure	Another brain disease, alone or alongside CCD	New seizures make another cause, or an extra one, likely, and the guidelines recommend an MRI (Olby 2026; Cornell)

Pain deserves a second look, because it can sit alongside CCD as well as mimic it. In a 2026 study of 88 senior dogs, dogs with higher owner-rated dementia scores took shorter strides with their front legs, and the link held after allowing for age and pain (Rafatpanah Baigi 2026). Pain scores were also linked to shorter strides (Rafatpanah Baigi 2026). The study shows a link, not cause and effect.

We cover several of these in more depth: walking in circles, staring at walls, seizures, blind dogs, drinking more water, back-leg weakness and house soiling.

When to get help fast

• Emergency, get veterinary care immediately: a seizure approaching five minutes, or repeated seizures without full recovery between them (Charalambous 2024), or more than one seizure within 24 hours. Also seek emergency care for collapse, inability to walk or severe sudden weakness.
• Call your vet the same day: a first brief seizure followed by full recovery, a new head tilt, circling always to one side, or behavior changes that came on over hours or days.

CCD comes on slowly and doesn’t cause one-sided signs. Sudden or one-sided changes point to another cause, or an extra one, and need checking even in a dog already diagnosed with CCD (Olby 2026).

When a neurologist or an MRI makes sense

Most dogs with CCD are diagnosed and cared for by their regular vet. In a 2025 survey of 318 US vets, 88 percent said they rarely or never refer dogs with suspected CCD to a specialist (Simon 2025). Those who do refer mostly send dogs to a veterinary neurologist, and some to a veterinary behaviorist (Simon 2025).

A referral to a veterinary neurologist is worth discussing when:

• the neurologic exam finds one-sided or focal signs, such as a head tilt, circling to one side or a cranial nerve problem, or your dog has a new seizure. The guidelines say an MRI and spinal fluid test should then be strongly considered before CCD is presumed (Olby 2026);
• the changes came on suddenly, or began before your dog was old. Neither fits the guidelines’ description of CCD as slowly progressive in an older dog (Olby 2026);
• you and your vet want the higher-certainty Level 2 diagnosis (Olby 2026).

What an MRI can and can’t show: its job is as much to rule out other brain disease as to support CCD (Olby 2026). The main CCD finding is brain shrinkage (atrophy), which also happens with healthy aging, so it adds confidence only when the history and signs fit (Olby 2026). Ways of measuring that shrinkage are still being standardized, and normal ranges for different ages and breeds haven’t been set (Olby 2026). The spinal fluid sample is taken under anesthesia right after the scan. In CCD it should be normal, while signs of inflammation, infection or cancer cells point to another diagnosis (Olby 2026).

The guidelines acknowledge that a full workup carries real cost and risk (Olby 2026), so it’s fair to ask your vet what the result would change for your dog.

If you’re a veterinarian, our CCD clinical notes for veterinarians go further.

What changes in the brain

CCD is a physical disease of the brain, not a training problem. The guidelines note that amyloid and tau changes are recognized, that other disease processes haven’t been explored yet, and that CCD likely has more than one cause (Olby 2026).

• Protein build-up. With age, a protein called beta-amyloid collects as plaques in brain tissue and in blood-vessel walls (Head 2013; Olby 2026). In dogs the plaques are mostly diffuse, unlike the dense-core “neuritic” plaques of advanced human Alzheimer’s, and how much amyloid has to do with the symptoms is debated (Olby 2026). A 2026 study of the brains of 24 senior pet dogs found more amyloid in dogs rated as cognitively impaired, though age predicted it best, and a second protein, tau, showed variable changes limited to some brain regions (Alsulami 2026).
• Oxidative damage. Aging dog brains build up oxidative damage to proteins, DNA, RNA and fats (Head 2011), and the guidelines list it among the changes found in CCD (Olby 2026).
• Shrinkage. The most prominent change is shrinkage of the brain’s outer layer (cortical atrophy), with loss of nerve cells in the hippocampus, loss of myelin (the insulation around nerve fibers) and inflammation. Shrinkage isn’t specific to CCD, and formal autopsy criteria for diagnosing it haven’t been set yet (Olby 2026).

Studies of normally aging dogs have also found changes in how the brain uses energy and in its blood flow (London 1983; Tabata 1986). They help explain brain aging but don’t by themselves show what causes CCD.

None of this is your dog choosing to ignore you or forget their training. For risk factors and what’s known about prevention, see what causes dog dementia.

After the diagnosis: what management looks like

There’s no cure for CCD (Dewey 2019). Management is a mix of approaches chosen for your dog, aimed at keeping a good quality of life (Dewey 2019; Lynch 2026). Specialists advise starting early, when they think it’s likely to do the most good, and the 2026 guidelines also say intervention may have the most impact early (Dewey 2019; Lynch 2026; Olby 2026). That’s expert opinion rather than a tested result: we found no study comparing earlier and later starts, and much of the research on slowing brain aging comes from laboratory-bred beagles, with the picture in pet dogs less well defined (Milgram 2005; Olby 2026). A change in day-to-day signs also isn’t proof that the disease itself has slowed.

Our treatment guide covers the full plan. The short version:

Veterinary care

Anything else the workup found, such as pain, is treated alongside the CCD (Olby 2026). Selegiline (sold as Anipryl) is the only drug approved by the FDA to control the clinical signs of CCD (FDA 1998; Simon 2025; Dondi 2026).

Its approval trial ran in two phases (FDA 1998):

• 4 weeks with a placebo comparison;
• 8 more weeks in which all dogs got the drug and there was no placebo group.

Some dogs that hadn’t improved by week 4 had improved by week 12, and the onset, length and size of the response varied from dog to dog (FDA 1998). Because the second phase had no placebo comparison, improvement between weeks 4 and 12 can’t show how much of that change the drug caused. Whether it suits your dog, alongside everything else they take, is your vet’s call. Our medication guide covers how it’s used, its side effects and other options.

Diet

Diets made for aging brains exist (Cornell). Much of the early research used laboratory beagles, though a double-blind, placebo-controlled diet trial has also been run in 87 pet dogs with signs of CCD (Milgram 2005; Pan 2018). Ask your vet whether a diet like this fits your dog, especially if kidney disease, weight or a sensitive stomach already limits what they can eat.

Enrichment and nights

Cornell’s guide lists enrichment alongside diet and medication in CCD care (Cornell). The best-known evidence comes from a two-year research program in older laboratory beagles, in which dogs given behavioral enrichment did better on a learning test than dogs without it (Milgram 2005). In a related analysis of the same program, 24 older dogs were divided into four groups of six, and the enrichment was a lab program (Christie 2009):

• learning tasks five times a week;
• housing with kennel-mates;
• leash walks of at least 20 minutes twice a week;
• new toys.

At home, our translation of that, not something the study tested, is short training refreshers, food puzzles, walks with time to sniff, and company.

In a 2026 survey of 858 dogs over 7, dogs that had done sports during their lives, or shared activities with their owners, had lower owner-rated CCD scores (Lugosi 2026). A survey taken at one point in time can’t show cause and effect.

For the night side of CCD, our sundowning guide has a printable night plan, and there’s more on enrichment and house soiling.

How CCD progresses, and how long dogs live with it

The 2026 guidelines describe three stages (Olby 2026):

• Mild: changes are subtle and infrequent or low in severity. The dog generally manages normal daily life, and owners often put the changes down to old age.
• Moderate: changes come more often and are more severe. They get in the way of daily life, and the way you manage your dog has to adjust.
• Severe: changes are obvious and debilitating. The dog needs help even with basic functions, and care has to be comprehensive.

The stages describe how disabled your dog seems to you, not how much damage there is in the brain (Olby 2026).

How fast dogs progress varies a lot (Schutt 2015). The two follow-up studies we found used their own categories, not the 2026 stages:

• in a 2015 study that classified dogs with the CADES questionnaire, 24 percent of dogs with mild cognitive impairment had moved to moderate impairment after six months, and 50 percent after twelve (Madari 2015);
• in another, 22 percent of dogs classed as having mild cognitive impairment progressed to CCD during two years of follow-up (Schutt 2015).

Neither figure is a forecast for your dog. Rescoring every six months, as the guidelines recommend from age 10 (Olby 2026), shows which way your own dog is heading.

How long dogs live with CCD. The studies we found don’t give a reliable estimate of how long a dog lives after a CCD diagnosis. Two follow-up studies of older dogs, one of 94 dogs and one of 51, did not find that CCD shortened survival (Fast 2013; Schutt 2015). Not finding a difference in small studies isn’t the same as showing there is none. In the smaller study, survival was counted from birth, so it describes lifespan rather than time after diagnosis (Schutt 2015). Dogs with severe signs or other serious illness often have a worse outlook (Cornell). Our stages guide covers what each stage looks like.

Living with CCD, and looking after yourself

Caring for a dog with CCD can wear on the whole household, and the guidelines note that changes in sleep are often tied to a heavier load for caregivers (Olby 2026). Our guide for caregivers is there for that. When the harder questions come, our quality-of-life guide is written for that time, with a Good Day / Bad Day tracker. You don’t need it today.

Bring this to your vet

Your notes are where the diagnosis starts. Print or copy this list before the appointment.

Before the visit

• For each change, note the date you first noticed it, how often it happens, and whether it crept in or came on suddenly.
• If your vet uses one, fill in a DISHAA questionnaire to review together. You can also use our short cognitive assessment to organize what you’ve seen, but it’s a screening aid, not a diagnostic tool, and it doesn’t replace your vet’s assessment.
• Have the same person fill in the questionnaire each time.
• Film the behaviors that worry you, especially at night, so your vet sees what you see.
• List every medicine and supplement your dog gets, with doses, and any other illnesses your dog has.
• Note any changes in eating, drinking, urinating and bowel movements.
• Note anything that could mean pain: stiffness, limping, or trouble with stairs or getting up.
• Note recent changes at home, such as a move, a new pet or a new schedule.
• Leave space for your vet’s plan: the next tests, any treatment, and the date to recheck.

Questions to ask

• What else could explain these signs, and which tests will check for it?
• Is my dog’s neurologic exam normal? Is anything one-sided?
• Should we treat the other problems you found first, then see what’s left?
• Which questionnaire will we use, and when should we score again?
• Would an MRI change what we do? When would you refer us to a neurologist?
• Is selegiline or another medicine right for my dog, and how will we tell if it’s helping?
• Do any of my dog’s current medicines or supplements need to change?
• Would a predictable daily routine for meals, walks and bedtime suit my dog?
• What should make me call you before the next visit?

Keep reading

Symptoms and signs (DISHAA)

The six DISHAA areas, with the everyday changes owners notice first.

Stages and life expectancy

How mild, moderate and severe CCD differ, and how vets track the change.

Sundowning and night care

Why nights get harder with CCD, and practical ways to settle a restless dog.

Review and disclosure

Dr. Curtis Dewey, who reviewed this page, formulated a cognitive-support supplement that Dr. Fossum’s Pet Care sells, and he receives a percentage of its sales. This page does not mention or link to that product.

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Frequently asked questions

This guide is educational and is not a substitute for veterinary diagnosis or care. If you are worried about your dog, talk to your veterinarian.