What should I do if my old dog’s behavior is changing?
Take it to your vet before you look for a training plan. Disorientation, changed interactions, a disturbed sleep cycle, house soiling, changed activity and anxiety are on the clinical list of signs of canine cognitive dysfunction (DISHAA), but pain, hearing loss and organ disease can cause them too, so the vet first rules out other causes (AAHA, 2023). Owners can easily miss the signs early on, and treatment works better the earlier it starts.
In short
The whole chapter in a few lines. Read further only where you want to know why.
- Six signs (DISHAA): disorientation, interactions, sleep, house soiling, activity, anxiety.
- “Stubborn in his old age” is a conclusion, not an observation: the same sign can mean poorer hearing, pain or cognitive decline.
- Leaking and house soiling are not the same thing, and both go to the vet.
- Write down what normal looks like today, with the date.
A breed summary is only a prejudice about the breed.
You can use prejudices — but get to know your own dog.
It depends on the breeding, the environment, and the dog’s own character. He may have all of the breed’s traits, some of them, or none. Every dog is his own.
1 How many older dogs have dementia, and why the numbers differ
Canine cognitive dysfunction — the dog version of dementia — is common in older dogs. The 2023 AAHA guidelines say that roughly 14 to 22.5% of dogs older than eight years have age-related cognitive impairment. Here is what individual studies measured:
| Who and how many dogs | What they found |
|---|---|
| Neilson et al., 2001 180 dogs aged 11 to 16; telephone interview with owners | Impairment in at least one of four areas (orientation, social interaction, house training, sleep–wake) in 28% of dogs aged 11–12 and 68% of dogs aged 15–16 |
| Salvin et al., 2010 497 dogs older than 8 (mean age 11.7); owner questionnaire | 14.2% showed signs of cognitive dysfunction, but only 1.9% had a veterinary diagnosis; prevalence rose with age and did not differ by breed size |
| Yarborough et al., 2022 15,019 dogs, mean age 6.9 years; owner survey (Dog Aging Project) | 1.4% showed signs; the odds rose 52% with each additional year of age |
The numbers differ because the studies counted different dogs and asked in different ways. The first two looked only at older dogs, while the third included younger ones as well (mean age 6.9 years), which pulls the percentage down. Salvin et al. also showed a second gap: in the same sample, 14.2% had signs by the owners’ questionnaire, while only 1.9% had been diagnosed by a vet. Most dogs with signs, in other words, have no diagnosis.
VCA recommends screening for cognitive decline once a year starting at age seven, and AAHA notes that owners may not recognize the signs in the early stages and that treatment works better the earlier it starts. We did not find a study measuring how common it is in French Bulldogs specifically.
2 The six signs of dementia in dogs (DISHAA)
The clinical framework has an acronym that Cornell, VCA and AAHA all use: DISHAA. It is worth knowing because it turns vague worry into six specific questions. The letters come from the English names: D disorientation, I interactions, S sleep–wake, H house soiling, A activity, A anxiety.
| Sign | What you actually see at home | |
|---|---|---|
| D | Disorientation | Gets lost in familiar places, has trouble finding the food or water bowl, tries to go through the wrong side of a doorway, does not recognize familiar people, may get stuck in a corner |
| I | Interactions | His way of relating to people and other pets changes — either clingier and more demanding, or withdrawn |
| S | Sleep–wake cycle | Sleeps more by day, restless and pacing at night; Cornell calls this often the first sign families notice |
| H | House soiling, learning and memory | A house-trained dog soils in unusual places; forgets to go while outside, then goes as soon as he is back in; does not respond to commands he used to know; adjusts more slowly to changes such as a new schedule |
| A | Activity | Less interest in play; rests more, or wanders and paces |
| A | Anxiety | Frightened of new things or of specific sounds, such as thunder; some dogs become uncomfortable when left home alone |
Cornell also describes sundowner syndrome: signs that get worse, with irritability, at night. And VCA notes that a dog who shows more than one of these signs may be dealing with more than routine aging and should have a physical and behavioral evaluation.
3 Changed sleep in an older flat-faced dog: aging, cognitive decline or breathing
A review of dog sleep (Niinikoski and Rajamäki, 2026) says older dogs sleep more by day and are less active, and that cognitive dysfunction adds more pronounced changes to the sleep–wake cycle: more restlessness and wandering at night.
A flat-faced dog has a third possible cause, sleep-disordered breathing. The same review lists, among the signs of possible sleep-disordered breathing in brachycephalic dogs, restless sleep, frequent arousals and hypersomnolence (excessive sleepiness by day). It also reports that owners of flat-faced dogs are significantly more likely to see sleeping sitting up as normal, and that daytime sleepiness is hard for owners to identify, because sleeping during the day is normal in dogs.
| What you notice | What can be behind it, according to those sources |
|---|---|
| Sleeps more by day | Aging · cognitive decline · sleep-disordered breathing |
| Restless, pacing, awake at night | Cognitive decline · sleep-disordered breathing |
Our opinion: at home you cannot tell whether a change in sleep comes from aging, cognitive decline or breathing, by day or by night, so the answer is the same in every case: the vet. It helps to bring your vet what you notice: how he sleeps (see the sleep chapter), and whether the short list of things he always got up for has gotten shorter.
Our opinion: that list is a practical daytime marker. Every dog has a short list of things he will always get up for — a particular noise outside, food, the leash, a visitor. When it shrinks, you have an observation that costs nothing and resembles one item on the VCA list: less interest in play. It is a reason to ask the vet, not to conclude anything.
4 Four sentences that sound harmless but can hide an illness
Each of these sentences sounds reasonable, and behind each one there can be something that is monitored or treated. VCA points out that behavior also changes with physical illness: a dog with arthritis may not get out of a comfortable bed to greet you, and a dog with kidney disease may not be able to hold his bladder and may urinate indoors.
| What gets said | What can be behind it |
|---|---|
| “He has gotten stubborn in his old age” | Not responding: hearing loss (Cornell), or commands he used to know that are gone (VCA) |
| “He is being spiteful, he knows better” | House soiling: VCA describes a dog who forgets to go while outside and goes as soon as he is back in; it can also be illness (kidney disease, VCA; bladder infection, Cornell) |
| “He is just needy now” | A changed relationship is one of the DISHAA signs (VCA): clingier and more demanding, or withdrawn |
| “Old dogs sleep badly” | Restlessness and pacing at night are on the list of signs (VCA, Cornell) |
Our opinion: old age explains when something is happening, not what it is. VCA puts it another way: a dog with more than one of these signs may have more than routine aging, and should be examined.
5 A treatable problem that gets filed as dementia
There is a second mistake: filing a treatable medical problem under dementia. According to the AAHA guidelines, cognitive dysfunction is a diagnosis of exclusion: the vet takes a history and does a physical and neurological examination, blood work and a urinalysis to rule out other disease, and the other explanations for similar behavior changes include tumors inside the skull, pain, and organ dysfunction. Cornell advises ruling out a bladder infection first.
House soiling is where this mistake is easiest to make, because two different things live under it. Here is what the sources describe:
| Urinary leaking (incontinence) | Cognitive house soiling | |
|---|---|---|
| What the sources describe | The most common sign is urine pooling or spotting under the dog when he is sleeping or relaxed, and he often seems unaware (VCA); otherwise he usually urinates normally (Merck) | A house-trained dog soils in unusual places, or forgets to go outside and goes as soon as he is back in (VCA) |
| What it is | The most common cause of this kind of incontinence is weakness of the muscles that close the urethra, most often in spayed females of middle age or older (Merck, VCA) | One of the signs of cognitive dysfunction, which is diagnosed by exclusion (AAHA) |
| Where it goes | The vet: diagnosed from history, examination, and blood and urine tests, and about 70% of cases respond well to medical therapy (VCA) | The vet: other diseases are ruled out first (AAHA) |
Our opinion: these are descriptions from the sources, not a test you can run at home. Both leaking and house soiling go to the vet, because a bladder infection, kidney disease or pain can cause the same sign. It helps to describe what you see: whether it leaks while he sleeps or you find a puddle when he is awake, how much, and whether he seems to notice. The general version of this topic is in accidents in the house.
6 Shorter walks: “he cannot walk as far as he used to”
Shorter walks in an older dog can have several causes. Wrightson et al. (2023; 804 older dogs, an online owner questionnaire) found that dogs with more cognitive decline also had more signs of musculoskeletal and neurological problems, including pain and sensory decline; as a cross-sectional study, it cannot show what causes what. In a flat-faced dog there is one more possible cause: the airway.
In this breed, exercise tolerance is part of how the airway is assessed: BOAS, the breathing disorder of flat-faced breeds, is graded by a clinical examination before and after an exercise tolerance test (Liu et al., 2017; 604 dogs, 214 of them French Bulldogs). In grade I the breathing noise is mild and exercise tolerance is unaffected.
Our opinion: that is why it is more useful to note at what point in the walk his breathing changes, and whether that point has moved, than how long he can walk. Both sentences below go to the vet:
| What you say | What it gives the vet |
|---|---|
| “He used to do an hour, now he does forty minutes” | A change in stamina; pain, breathing or cognitive decline are possible causes, and the vet tells them apart |
| “He used to start sounding rough at forty minutes, now it is at fifteen” | A change in breathing in relation to movement, more specific information for assessing the airway |
Note the minute and the date, and tell your vet; if the change is new or getting worse, do not wait for the next routine checkup. The judgment is the vet’s — see BOAS and sleep.
7 What helps
VCA describes cognitive dysfunction as chronic, slowly progressive and irreversible, and Cornell puts it this way: you cannot stop aging, but you can help slow its progression.
Enrichment. Cornell and VCA advise keeping him using his head: practicing old tricks and teaching new ones every day, sniff walks, food puzzles, scent games. Make sure he seems to enjoy what you offer. VCA adds that play and physical exercise are important for brain health, that an exercise program that is safe for your dog should be designed with your vet, and that his weight should be watched, because extra weight harms the brain and the body.
Diet. AAHA says that diets high in antioxidants and medium-chain triglycerides (a type of fat) showed the most positive effect when combined with environmental enrichment, and that the quality and rigor of research on other supplements and diets is limited; VCA says the same about food-based supplements. Here are two studies behind that:
| Who and how many dogs | What they found |
|---|---|
| Pan et al., 2018 87 dogs aged 9 to 16, 24 clinics, 90 days; double-blind (neither the owners nor the researchers knew which food each dog was eating), compared with a control food | A food with added medium-chain triglycerides and a blend of vitamins, antioxidants and omega-3 fatty acids improved all six areas of signs from section 2. The control food (ordinary food for comparison) also improved three areas at day 30 (sleep, house training and activity), and by day 90 it had not improved disorientation or interactions. The study was entirely funded by Nestlé Purina, whose employees are among the authors; the data came from owners’ questionnaires |
| Milgram et al., 2004 48 aged beagles (9–12 years) in a laboratory, four groups of 12 | Both a food fortified with antioxidants and an enriched environment improved learning, and the effect was mostly seen in the group that had both |
Which food, and whether it suits your dog, is a conversation with your vet — not a purchase you make from an article.
Our experience: Spike is almost eight years old, eats well and, for his age, is holding up excellently. That is one dog, not proof; we write it down so you can see that we do not write only from sources, but also from our own experience.
Medication. According to VCA, one medication is licensed for cognitive decline in dogs in North America. It is prescription-only, and what to use, when, and whether at all is your vet’s decision. We do not give doses or recommend drugs anywhere on this site.
The environment and safety. Cornell and VCA advise:
- block off stairs and the space behind the couch where he can get stuck;
- add night lights;
- keep the routine steady, and the bowls and bed in fixed places;
- put down runners for traction, and ramps instead of jumps;
- if his hearing is going, speak and stamp a foot before you approach a sleeping dog, so he feels the vibration through the floor;
- make sure he always wears identification and that his microchip details are current: a dog who gets out may not be able to find his way home (Cornell).
That is why the vet comes first. In 804 senior dogs (Wrightson et al., 2023; see the previous section) more cognitive decline came with more signs of pain and sensory decline, and the authors advise looking for concurrent disease when assessing cognitive decline.
8 Write down today what normal looks like, while your dog is well
Cognitive decline is followed through change: AAHA notes that owners fill in questionnaires at set intervals and that the scores from several rounds are compared over time. Which means the most useful thing you can do for an older dog is done while there is nothing wrong.
Write down six lines and a date: one line for each of the six signs in section 2 (disorientation, interactions, sleep, house soiling, activity, anxiety), in your own words, as they are today, plus his age. This is the baseline: a record of how things are today. Cornell also offers a questionnaire that scores each category from 0 to 3 and advises taking the result to the vet. The whole exercise takes one evening and no appointment.
Our opinion: a baseline that says “nothing wrong” is worth exactly as much as one full of findings, because its value is not the content: it is the date. Without it, next year’s conversation is an argument about memory. With it, it is a comparison.
Add two notes from the chapters next door while you are at it: how he sleeps (the questions in the sleep chapter) and at which minute of a walk his breathing changes. Both are yours to notice, and both belong in the same notebook. Cornell also advises checkups at the vet at least every six months for a senior dog.
9 Spike: our experience
Our stories and opinions on this page are our personal experience with one dog, Spike. One dog is not the measure for every dog — for your dog, your vet decides.
“Nothing to report. That is exactly why we wrote it down.”
Spike is almost eight years old and has no cognitive signs. It shows that he is not a young dog: he has slowed down a little, he is a little more sluggish and he sleeps a little more, but he shows no signs of greater old age. He knows where everything is, he plays, he runs, he is as independent as he has always been, he rarely wakes, and he is almost silent in his sleep.
For a dog of almost eight, Spike is holding up excellently, and we think that is because he is extremely active for his age (he plays, he runs, he walks for over an hour) and eats well. So we keep to the rule “keep them fit”: plenty of movement and good food, so the dog stays lively, in good spirits and healthy for as long as possible. The movement should stay within what his breathing and the heat allow. These are two things an owner can do starting today. What VCA says about exercise and weight is in section 7.
We did the exercise from the section above on our own dog, and the useful part is that it is dated:
| Our baseline | |
|---|---|
| D — disorientation | None. Knows where everything is, does not approach doors from the wrong side, does not get stuck in corners, does not stare |
| I — interactions | Unchanged: independent, territorial, attached to his person |
| S — sleep–wake | Sleeps a little more by day than before; rarely wakes, almost silent in sleep |
| H — house soiling | We keep this one as a vet question rather than a checkbox, because house soiling has more than one possible cause (see section 5) |
| A — activity | Has slowed down a little, but still plays, runs, does tug-of-war and comes out like a bullet |
| A — anxiety | No separation anxiety (our description, no formal assessment). He reacts to fireworks and not to thunder, as he has for all these years, so nothing new |
| Stamina | Walks are shorter than they used to be: from about three hours “like a madman” to over an hour. Written down as a number, with a date |
His daytime list is the one we would watch: gossip, food, and a walk. If something is happening outside worth investigating, or there is food, or the leash comes out, he is there. The rest of the day he rests and sleeps in several bouts. If that list ever gets shorter, that is the day we ask.
We do not interpret the shorter walks ourselves. We wrote the number down with a date, so that in a year it is a comparison and not an argument about memory, and the assessment is the vet’s. Something is also missing on our side: we use a three-level breathing scale on every walk (see sleep), and our notes do not say at which minute of the walk level 2 arrives. That is the number that would tell us something.
Owners Also Ask
What should I do if my old dog’s behavior is changing?
Take it to your vet before you look for a training plan. Disorientation, changed interactions, a disturbed sleep cycle, house soiling, changed activity and anxiety are on the clinical list of signs of canine cognitive dysfunction (DISHAA), but pain, hearing loss and organ disease can cause them too, so the vet first rules out other causes (AAHA, 2023). Owners can easily miss the signs early on, and treatment works better the earlier it starts.
What are the signs of dementia in dogs?
The clinical framework is DISHAA (Cornell, VCA, AAHA): disorientation, changed interactions with people and other pets, a changed sleep-wake cycle (more sleep by day, restlessness at night), house soiling and forgotten commands in a house-trained dog, changed activity, and anxiety. Cornell describes signs that get worse at night. VCA says a dog with more than one of these signs should be examined.
My senior dog sleeps all day. Is that dementia?
It can be aging, cognitive decline or sleep-disordered breathing, and the vet tells them apart. A 2026 review says older dogs sleep more by day and are less active, that cognitive dysfunction brings restlessness and wandering at night, and that in flat-faced dogs excessive sleepiness and restless sleep are among the signs of possible sleep-disordered breathing. Our opinion: a dog who lies around all day and does not wake for what usually wakes him is not well, so ask the vet, and describe how he sleeps at night.
My old dog is leaking urine. Is it the dementia?
That is for the vet to decide. Leaking and house soiling are not the same thing: weakness of the muscles that close the urethra is the most common cause of this kind of incontinence (Merck, VCA), while house soiling is one of the signs of cognitive dysfunction, which is diagnosed by exclusion (AAHA). A bladder infection (Cornell) or kidney disease (VCA) can cause the same sign. Tell your vet what you see: whether it leaks while he sleeps, how much, and whether he seems to notice.
Can anything be done about canine cognitive dysfunction?
It can be eased, but not reversed: VCA calls it chronic, slowly progressive and irreversible. Enrichment and diet are the everyday side; AAHA says diets high in antioxidants and medium-chain triglycerides did best when combined with enrichment, and a double-blind study of 87 dogs, funded by the food maker, found improvement on such a food and on the control food. Ask your vet before you change your dog’s food. A licensed medication exists and is prescription-only, so whether it fits your dog is your vet’s decision. Cornell advises a steady routine, night lights and blocked stairs.
References
- Cornell Riney Canine Health Center — Senior dog dementia (article from the DogWatch newsletter). vet.cornell.edu
- Lindell E, Horwitz D, Landsberg G. Cognitive Dysfunction Syndrome in Senior Dogs and Cats. VCA Animal Hospitals. vcahospitals.com
- AAHA 2023 Senior Care Guidelines for Dogs and Cats — Managing Cognitive Dysfunction and Behavioral Anxiety. aaha.org
- Neilson JC, Hart BL, Cliff KD, Ruehl WW. Prevalence of behavioral changes associated with age-related cognitive impairment in dogs. Journal of the American Veterinary Medical Association 218(11):1787–1791, 2001. pubmed.ncbi.nlm.nih.gov
- Salvin HE, McGreevy PD, Sachdev PS, Valenzuela MJ. Under diagnosis of canine cognitive dysfunction: a cross-sectional survey of older companion dogs. The Veterinary Journal 184(3):277–281, 2010. pubmed.ncbi.nlm.nih.gov
- Yarborough S, Fitzpatrick A, Schwartz SM; Dog Aging Project Consortium. Evaluation of cognitive function in the Dog Aging Project: associations with baseline canine characteristics. Scientific Reports 12:13316, 2022. pmc.ncbi.nlm.nih.gov
- Pan Y, Landsberg G, Mougeot I, Kelly S, Xu H, Bhatnagar S, Gardner CL, Milgram NW. Efficacy of a therapeutic diet on dogs with signs of cognitive dysfunction syndrome (CDS): a prospective double blinded placebo controlled clinical study. Frontiers in Nutrition 5:127, 2018. pmc.ncbi.nlm.nih.gov
- Milgram NW, Head E, Zicker SC, Ikeda-Douglas C, Murphey H, Muggenberg BA, Siwak CT, Tapp PD, Lowry SR, Cotman CW. Long-term treatment with antioxidants and a program of behavioral enrichment reduces age-dependent impairment in discrimination and reversal learning in beagle dogs. Experimental Gerontology 39(5):753–765, 2004. pubmed.ncbi.nlm.nih.gov
- Wrightson R, Albertini M, Pirrone F, McPeake K, Piotti P. The relationship between signs of medical conditions and cognitive decline in senior dogs. Animals 13(13):2203, 2023. pmc.ncbi.nlm.nih.gov
- Niinikoski I, Rajamäki MM. Association of brachycephaly, sleep-disordered breathing, and inflammatory response in dogs. Journal of Veterinary Internal Medicine 40(4):aalag126, 2026. pmc.ncbi.nlm.nih.gov
- Liu NC, Troconis EL, Kalmar L, Price DJ, Wright HE, Adams VJ, Sargan DR, Ladlow JF. Conformational risk factors of brachycephalic obstructive airway syndrome (BOAS) in pugs, French bulldogs, and bulldogs. PLoS ONE 12:e0181928, 2017. pmc.ncbi.nlm.nih.gov
- Van Vertloo L. Disorders of micturition in dogs and cats. Merck Veterinary Manual (peer reviewed; last updated March 2025). merckvetmanual.com
- Weir M, Hunter T, Ward E. Urinary Incontinence (Urethral Incontinence) in Dogs. VCA Animal Hospitals. vcahospitals.com
