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Veterinary Focus

Issue number 33.3 Behavior

Canine cognitive dysfunction

Published 26/01/2024

Written by Beverley M. Wilson and Daniel S. Mills

Also available in Français , Deutsch , Italiano and Español

Canine “dementia” is becoming more common as our pet population ages; this article reviews the signs, differential diagnoses and treatment for such cases.

check if a dog that has possible signs of CCD

Key points

Canine Cognitive Dysfunction (CCD) is a common problem in elderly dogs, but it can be managed to improve the welfare of both patients and owners.

Early recognition and intervention is key to an improved prognosis for CCD.

Many conditions can mimic CCD, so it is important to consider a range of medical differentials and comorbidities when assessing possible cases.

Combining several management options (such as environmental or diet changes and nutraceuticals) have been shown to be the most effective treatment for CCD.

Introduction to CCD

Canine cognitive dysfunction (CCD) is a form of dementia affecting geriatric dogs 1 and although it cannot be cured, the clinical signs can be managed and the prognosis improved with early detection and intervention 2,3. The condition is probably more common than is generally recognized 4 as dog owners often attribute the signs to part of the normal aging process and/or believe they are untreatable 5, and so do not discuss their concerns with their veterinarian 1. Indeed, it has been estimated that somewhere between 22.5-68% of elderly dogs express at least one sign of cognitive dysfunction 1,3,6, although this does not mean they necessarily have CCD, as the signs may be associated with other issues such as chronic pain. Accordingly, CCD is an important disease for veterinary professionals to be aware of, and it should be proactively discussed with owners in order to improve the health and welfare of elderly pet dogs (Figure 1). This article will consider the key signs, diagnosis and differentials of CCD, and discuss treatment options and the outlook for the condition.

Owners may think that their dog is simply showing a normal aging process

Figure 1. Owners may think that their dog is simply showing a normal aging process, so the clinician should be proactive in discussing possible signs of CCD during any consultation.
© Shutterstock

Presentation and etiology

CCD is a condition of older age, and therefore occurs in geriatric patients; it is commonly reported from 11 years of age, although this varies with the size of the dog and the typical life expectancy of the breed. In some studies females are reported to be more likely to be diagnosed with CCD 1. However, castrated male dogs and smaller dogs are believed to be more prone to demonstrating signs of CCD, and castrated dogs may deteriorate more rapidly 6.

The behavioral signs of CCD are frequently described using the acronym DISHA 7 (Table 1), but the acronyms DISHAA and DISHAAL may also be used, with the additional A standing for anxiety or apathy, and the L for learning 7,8. Regardless of the preferred acronym, it is important to appreciate that there are wider emotional issues in many cases relating to temperament, mood and immediate emotional responses, such as depressive states, poor frustration tolerance or increased attention seeking, in addition to the more classic avoidance responses associated with anxiety. Table 1 reviews the classic signs relating to DISHA and important differentials to consider. Dogs vary enormously in the reported signs in the initial stages, with no consistent pattern evident 9, so early detection can be challenging. However, CCD is a progressive disease and so further signs are commonly reported over time, which means it is important to monitor these cases from the first time a sign is noticed, even if a diagnosis is not made at that time. Indeed, many owners may only seek support from the veterinarian when particular signs are causing a problem for either the dog or themselves. For example, a sudden loss of a previously known behavior (e.g., recall when off lead), house soiling (Figure 2), significantly reduced activity/interaction with the owners, or night-time waking. In these cases, the owner’s focus is on the behavior problem, but it is essential to appreciate that the issue may be more complex due to the potential role of underlying neurodegenerative changes associated with CCD. The importance of thorough history taking during consultations cannot be overstated, as many owners may be unaware of important signs or may not appreciate that they can be addressed, often assuming the changes seen are part of an inevitable aging process. Senior pet health checks and routine appointments (such as for vaccinations) provide an opportunity to actively ask an owner about signs of CCD.

Table 1. Cardinal signs of CCD with examples and common differentials to consider.

Cardinal sign (DISHA) Examples Possible differentials
  • Appearing lost in familiar locations
  • Loss of hearing/vision
  • Struggling with obstacles – e.g., going to wrong side of door or unable to navigate around furniture
  • Mobility issues – e.g., osteoarthritis
  • Loss of vision
Interactions altered in relation to social stimuli
  • Increased contact with owner
  • Discomfort (e.g., osteoarthritis)
  • Endocrinopathy (e.g., hypothyroidism)
  • Liver disease
  • Neurological issue (e.g., space-occupying lesion)
  • Hypertension
  • Social withdrawal
  • Conflicts or reduced interactions with household animals
Sleep/wake changes
  • Night-time waking
  • Discomfort
  • Endocrinopathy
  • Causes of polyuria/polydipsia (PUPD) 
  • Liver disease
  • Anemia
  • Lethargy during the day
House soiling
  • Toileting overnight
  • Change in toileting location
  • Discomfort (e.g., cannot access areas previously used)
  • Liver disease
  • Renal disease 
  • Endocrinopathy/other causes of PUPD
Activity levels alterations
  • Pacing
  • Stereotypic behaviors
  • Increased/decreased activity
  • Neurological issue (e.g., space-occupying lesion)
  • Discomfort
  • Liver disease
  • Hypertension

CCD is used as a model for Alzheimer’s disease in people, so it is not surprising that the pathology has been studied extensively 10. Changes noted within the brains of dogs affected by CCD include reduced brain mass, reduced frontal lobe volume, cortical atrophy, reduced neuronal density, increased ventricular size and increased beta-amyloid plaques 7. In humans tau protein fibrils are also noted in Alzheimer’s, but this pathology is more typically found in cats (who coincidentally do not typically show the amyloid plaques found in humans and dogs). Given that the lesions are irreversible and their causal significance not well established, the pathology will not be discussed further here. 

A sudden loss of a previously known behavior, such as house soiling, may potentially be a sign of the underlying neurodegenerative changes associated with CCD

Figure 2. A sudden loss of a previously known behavior, such as house soiling, may potentially be a sign of the underlying neurodegenerative changes associated with CCD.
© Shutterstock

Diagnosis of CCD

CCD is a diagnosis of exclusion, and there are no definitive antemortem diagnostic tests available. A presumptive diagnosis is reached through the information provided by the owner and by ruling out other conditions which could be responsible for the clinical signs 4. Given the presenting signs there are many possible differential diagnoses which need to be excluded (Table 1) and information obtained from the owners is central to the clinical presumptive diagnosis of CCD; to aid this process in terms of speed, consistency and completeness, various screening questionnaires are available 11. Some of these can be completed independently by the owner, such as the canine cognitive dysfunction rating scale (CCDR) 12, which can be given to the owner to complete prior to the appointment and then discussed within the consultation (see Box 1). Others can be completed during the consultation, such as the age-related cognitive and affective disorders score (ARCAD) 13.

Box 1. Canine Cognitive Dysfunction Rating (CCDR) Scale (adapted from 12).



Canine cognitive dysfunction (CCD) or doggy dementia is an age-related syndrome which presents with changes in behavior. It usually affects dogs over 8 years of age although it is more common in later years, with over 30% of dogs over 14 years estimated to have the disease. Behaviors that may be affected include:

  • Sleeping and/or activity patterns
  • Eating and drinking
  • Spatial awareness and orientation
  • Learning and memory



The CCDR is an assessment tool designed to identify possible symptoms of CCD. The presence of enough symptoms in sufficient severity may be indicative of your dog having CCD. Despite this, it is important to remember that diseases of other body systems may also cause similar symptoms and your dog should be thoroughly examined by a veterinarian before a final diagnosis is made.



To complete the CCDR, select the most appropriate response for each question by marking it in the boxes provided. Only mark ONE response per question/line. Try to answer each question to the best of your knowledge based on your dog’s current behavior or changes in its behavior in the last 6 months.

IMPORTANT: If your dog never displays a behavior now and it never displayed this behavior 6 months ago, select THE SAME in the appropriate change related questions.

To determine your dog’s CCDR score put the number for the response column you selected in the score box to the right of each question. For example: If your dog stares blankly at the walls or floor “once a week” it scores a 3 for that question. If there is a x 2 or x 3 next to the score you will need to multiply the number for the response column you selected by either two or three to give a final score. For example: If your dog fails to recognize familiar people or pets “slightly more” than 6 months ago it scores a 4 for that column and then is multiplied by 3 to give a final score of 12 for that question. 



Finally, add up all of the scores to give the total. If your dog scored 50 or above there is a risk that it may have CCD and you should follow this up with your veterinarian. If your dog scored between 40 and 50 you should reassess your dog in 6 months’ time to determine if there has been any change.




  Never Once a month  Once a week Once a day > Once a day     
How often does your dog pace up and down, walk in circles and/or wander with no direction or purpose?              
How often does your dog stare blankly at the walls or floor?              
How often does your dog get stuck behind objects and is unable to get around?              
How often does your dog fail to recognize familiar people or pets?              
How often does your dog walk into walls or doors?              
How often does your dog walk away while, or to avoid, being patted?              
  Never 1-30% of times 31-60% of times 61-99% of times Always     
How often does your dog have difficulty finding food dropped on the floor?              
  Much less Slightly less  The same Slightly more Much more    
Compared with 6 months ago, does your dog now pace up and down, walk in circles and/or wander with no direction or purpose?              
Compared with 6 months ago, does your dog now stare blankly at the walls or floor?              
Compared with 6 months ago, does your dog urinate or defecate in an area it has previously kept clean (if your dog has never house-soiled, tick “the same”)?              
Compared with 6 months ago, does your dog have difficulty finding food dropped on the floor?            x2   
Compared with 6 months ago, does your dog fail to recognize familiar people or pets?            x3   
  Much more Slightly more  The same Slightly less Much less    
Compared with 6 months ago, what are your dog’s activity levels like?              

In the authors’ experience the CCDR scale is easy to use and can be given to owners to be completed at home if the veterinarian has suspicions of CCD based on the initial information obtained during a consultation (for example, from the history-taking process at a routine booster vaccination). This allows the owner to reflect on their pet’s aging and creates a pathway for engagement in proactive geriatric care.

Given the concerns regarding the under-reporting of CCD, and the potential for subtle but progressive clinical signs, it is recommended owners complete a suitable questionnaire every 6 months for their geriatric dog. This allows early detection of possible CCD and intervention to improve treatment outcomes 12 as it helps distinguish between normal cognitive decline associated with aging and dysfunction.

In addition to the owner history and reported information, the other essential is to check for possible differential diagnoses. The diagnostic tests will depend on the presenting signs for each individual case, and it should be noted that co-morbidity is common. If other differentials have been excluded, a presumptive diagnosis of CCD can be made, but where the picture is obscured by co-occurring conditions with similar signs, clinical judgement must be used, and the uncertainties carefully explained to the client. It is always prudent to review the potential for a diagnosis of CCD whenever a case with related clinical signs does not improve or stabilize as expected, or if there is a sudden deterioration or progression of signs. Likewise, the involvement of unrelated pathologies should be considered in cases of CCD which show a similar pattern of change. For example, if a dog with a diagnosis of CCD fails to improve as expected, this should suggest other factors could be involved, and the case should be re-evaluated for underlying problems such as chronic discomfort which may mimic or contribute to the CCD signs identified.

Beverley M. Wilson

Canine Cognitive Dysfunction is a diagnosis of exclusion and there are no definitive antemortem diagnostic tests available.

Beverley M. Wilson

Common differentials for CCD

There are numerous conditions which have a similar presentation to CCD, and it is important to consider each of these for every suspected CCD case.


Chronic discomfort can mimic many of the signs of CCD, including altered social interactions, sleep/wake cycles, house soiling and activity levels. For example, a dog which has become more withdrawn and less inclined to interact with the owner or other animals in the household may be experiencing osteoarthritic pain and so be reluctant or slow to rise (Figure 3); it may spend more time lying down, or be less willing to interact and play with other dogs in the household, as this may exacerbate the discomfort. In some cases, there may be a sudden onset of aggressive behaviors between the dogs, as the individual experiencing discomfort aims to prevent and repel such interactions. Chronic discomfort can be difficult to recognize, especially if the dog is still able to participate in some normal activities (such as daily exercise, because the immediate motivation to go for a walk overrides any discomfort experienced, at least in the short term). Often these cases may not show overt signs during clinical examination, posing a further diagnostic challenge. In general, if there are suspicions of discomfort, a pain relief trial for a minimum of 4-6 weeks should be used to help evaluate the role of chronic discomfort. It is important to coach the owners that the typical response to the trial will be slow and possibly subtle, and so a behavioral diary can be invaluable to capture these changes. Equally, a gradual deterioration following cessation of the pain relief may be the only reported sign, which would support the suspicion of discomfort. 

A dog which has become more withdrawn and spends long periods lying down may have CCD

Figure 3. A dog which has become more withdrawn and spends long periods lying down may have CCD, but in reality it may be experiencing osteoarthritic pain.
© Shutterstock

Changes in hearing, vision and smell

Loss of hearing, vision and smell can resemble some of the DISHA signs 14. For example, a dog with compromised vision can be reluctant to exercise, or may stay closer to the owners on walks or appear disorientated (Figure 4). A thorough physical examination and history taking specifically related to these areas can be beneficial to assess the role of altered senses. 

It is important to check if a dog that has possible signs of CCD has other problems that could be partially or totally responsible

Figure 4. It is important to check if a dog that has possible signs of CCD has other problems that could be partially or totally responsible; for example, a dog with compromised vision may start to stay closer to the owners on walks.
© Shutterstock

Systemic disease

Pathologies affecting many of the major organs can also lead to signs that mimic CCD. For example, reduced activity levels can be caused by dysfunction in the cardiovascular, respiratory, renal or endocrine systems, and the veterinarian must be careful not to approach a case with a preconceived idea as to the cause. If the dog is of the right age, the potential role of CCD alongside these conditions must be considered. Diagnostic tests should be undertaken to rule in or out medical factors which could contribute to the observed signs.

Normal cognitive decline

As part of the normal aging process dogs, like people, will experience a decline in cognition. The questionnaires described above help differentiate cognitive decline from cognitive dysfunction 12. Some dogs will remain in cognitive decline, whereas others will experience signs of dysfunction, hence it is important for the questionnaires to be completed every 6 months, or more often if needed, to help identify signs of dysfunction.

Daniel S. Mills

Canine Cognitive Disorder is a progressive disease and it can be difficult to predict response to treatment or rate of progression for the condition.

Daniel S. Mills

Management and treatment options

Although CCD cannot be cured, early intervention can help slow the progression and improve the quality of life for both the dog and owner 15,16. Management options include medications, nutraceuticals, diet, environmental and behavioral modification. Studies show the most effective combination to be a combination of environmental measures and diet/nutraceuticals 17. Table 2 summarizes common treatments commercially available where there is published evidence of efficacy.

In addition, it is also possible to use symptomatic treatment for specific clinical signs as required. For example, if an animal is struggling with night-time waking despite all other reported signs being well managed with dietary and environmental intervention (and checks have been made to rule out comorbidities) then the following could be considered:

  • Setting a nighttime routine to promote a restful state, e.g., walking and feeding in the evenings and closing the curtains to reduce light/noise.
  • Medications which may promote sleep, either directly or as a beneficial “side effect” (e.g., chlorphenamine or melatonin).

It is important in such cases for the veterinarian to work closely with the client to discuss the behaviors of concern. As with any chronic condition, owners can find the management and lack of resolution of clinical signs frustrating and upsetting, so an empathetic approach will help. Effective communication regarding treatment options is also key, as the owner needs to be aware the clinical signs are unlikely to completely resolve, but the aim is to reduce the speed of progression and manage specific signs as needed. It is also vital to discuss the potential risks and benefits of each treatment option, especially in light of concurrent health issues which may be present in senior patients.

Table 2. Common treatments commercially available for CCD.

Treatment category Treatment aim/purpose and expected outcome
Medication Selegiline Demonstrated improvement in reported clinical signs and improved learning and memory; 15,18
Propentofylline Improvement in mental dullness, lethargy and demeanor; improvement in some CCD signs, but some literature suggests no effect seen 19
Diet (antioxidants, mitochondrial enzymatic cofactors)  Shown to reduce cognitive decline; reduced speed of deterioration at learning tasks; improvement in clinical signs of CCD 2,20
 Nutraceuticals       SAMe  Improvement in CCD signs; improvement reported in activity and awareness 21
 Antioxidant supplements   Improvement in reported clinical signs, particularly disorientation, interactions and house soiling 9,22
 Environmental modification (novel toys, exercise) Demonstrated to reduce cognitive decline and reduce speed of progression of clinical signs 2,23
 Behavioral modification (games, training, exercise) Demonstrated to slow cognitive decline and reduce speed of progression of clinical signs 2
 Pheromones Reduction in observed signs of anxiety 8

Pragmatic considerations

Given the reported prevalence of CCD, first-opinion veterinarians are likely to see patients frequently, and the wealth of treatment options can at first appear overwhelming. However, it is important to remember that a combination of treatments will be necessary in order to maximize benefits for the individual patient. An individualistic approach is recommended, tailoring treatment based on the dog’s reported problem(s), as well as wider animal (such as concurrent conditions) and owner factors (such as lifestyle, time and ability to train). The primary aim is to improve the quality of life for patient and client by stabilizing or managing reported signs.

The owner’s autonomy and wishes with regards to assessment and treatment costs must always be respected and accommodated, but that does not mean that owner-related behavior change cannot be encouraged. A pragmatic approach is often necessary, as it may not be appropriate to perform as many diagnostic tests as desired. There may also be reported behaviors which the owner does not feel it is necessary to address, as they do not view them as problematic, or they accept them provided their dog is enjoying a reasonable quality of life. The case studies in Boxes 2 and 3 illustrate some of the challenges that might be involved and appropriate courses of action, and highlight the importance of clinical skills, communication and professional judgement in order to create a bespoke plan, which can be highly rewarding for the veterinarian as well as significantly improving the quality of life for both dog and owner.

Box 2. Case study example 1.

A dog who used to walk perfectly at exercise has begun pulling on the lead and no longer walks on a loose lead, due to altered learning and cognition with CCD. The dog is started on dietary modification and environmental enrichment, but the owner declines support for reschooling in loose-lead walking, as the dog’s concurrent arthritis means that long walks are no longer an option. The owner accepts that the dog will pull for its 10-minute walk around the village, and enjoys setting up scent games in the garden as enrichment for the dog to investigate. 

The veterinarian’s role here is to:

  • Assess the risk of the problem behavior: a different approach may need to be adopted if the dog was a giant breed who risked injuring their elderly owner by pulling on the lead.
  • Assess the health of the patient: is pulling on the lead likely to worsen signs related to any concurrent conditions such as osteoarthritis (as in this case)? In older medium to large breed dogs conditions such as laryngeal paralysis, osteoarthritis of the neck and forelimbs or intervertebral disc disease may also need to be considered.
  • Help the owner appreciate what management options are available: these may be simple changes (e.g., changing from a collar to a harness if there are neck issues) or more complex behavior modification options (e.g., fun loose-lead walking/training in the garden, perhaps in place of some of the scent games).
  • Potentially advocate for the patient: e.g., the owner may not be concerned with the dog pulling, but the veterinarian may notice potential signs of discomfort on clinical examination, such as reluctance when assessing range of motion of the neck. This might be supported by the dog’s behavior in the consultation room which the owner may not appreciate, such as a reluctance to pick a treat off the floor compared to treats eagerly and readily accepted from the veterinarian’s hand. Here good communication skills are needed to highlight to the owner that pulling on the lead may be exacerbating discomfort, so it would be beneficial to address this. The most appropriate behavior modification plan can then be collaboratively designed by the client and veterinarian.
  • Keeping an overview of multiple comorbidities and concurrent treatments; remember there is little published information regarding concurrent use of many medications, nutraceuticals and diets when comorbidities are present. As such the veterinarian will need be conscious of possible interactions with items which the owner may be giving for conditions such as osteoarthritis, and since many supplements are freely available over the counter it is vital to specifically ask the owner about these. Caution should also be exercised in relation to products and diets which contain the same, or similarly acting, ingredients, as there is a risk of “over supplementation” and potentially overdosing.
  • Offering dietary advice. Advise the owner that a recommended diet may be beneficial when it is fed exclusively, rather than when mixed with other foods. A pragmatic approach may be needed if palatability is an issue to ease transition from the previous diet.

Box 3. Case study example 2.

A dog has already been diagnosed with CCD and osteoarthritis, and management is in place for both conditions, but the owners report a new complaint of sudden onset house soiling. The following approach would be appropriate: 

  • Collect a thorough history regarding both the dog’s general health and behavioral history, including signs suggestive of PUPD, pollakiuria, location, frequency and onset of house soiling, how the owners are cleaning the soiled areas and interacting with the dog at these times. Further clinical diagnostic tests are then run as appropriate. Here there is no history of PUPD or pollakiuria, so a free catch urine sample is obtained. The urine specific gravity (USG), dipstick and sediment examination are within normal limits. The dog’s recent previous blood sample also did not give any cause for concern. It may be that the house soiling is most likely due to CCD, however discomfort due to OA cannot be excluded, although there may be no other compatible signs from the history. As a precautionary measure analgesia might be increased on a trial basis for 4 weeks while the owner maintains a diary to monitor progress (including measures of comfort, house soiling and activity levels).
  • Advise on managing the house soiling while the role of discomfort is further investigated. Provide a cleaning regimen (e.g., using an enzymatic cleaner), and advise taking the dog out regularly to the toilet, praising and rewarding whenever urine and feces are voided in appropriate areas, and possibly placing puppy pads in appropriate areas for when the dog is unsupervised. The owner may also be coached on how to set the dog up for success, e.g., by structuring the day with regular toilet breaks (such as after eating or waking) and avoiding the use of punishment (which can lead to the dog toileting in the owner’s absence and increase fear/anxiety) and creating a non-slip environment to allow easier access the garden (e.g., non-slip mats on any laminate or tiled floors which the dog has to walk across). 

Geriatric dogs should be routinely evaluated for signs of CCD 12 and records of their questionnaire score should form part of their routine clinical notes (Figure 5). For dogs showing signs of CCD which are well managed, check-ups every 3 to 6 months may be all that is required, whereas more frequent contact will be required if the signs are progressive or not yet stabilized. For dogs that show persistent signs or a sudden deterioration, it is important to screen for any concurrent health issues which may have developed or progressed since the diagnosis of CCD. For example, if a dog previously showing mild signs of disorientation has suddenly begun to house soil then it is important to check for conditions such as osteoarthritis affecting their ability to toilet outside (e.g., steps to get outside, a considerable distance from resting place to garden, or a slippery floor), renal, liver or endocrine disease (leading to polyuria/polydipsia (PUPD) and possibly a contributing urinary tract infection). 

Geriatric dogs

Figure 5. Geriatric dogs should be routinely evaluated for signs of CCD, and records of their questionnaire score should form part of their routine clinical notes.
© Shutterstock


CCD is a progressive disease, and it can be difficult to predict response to treatment or rate of progression for the condition. Clearly patients with comorbidities have a more guarded prognosis. Owners should be encouraged to monitor the key signs (not just those of initial concern) and be made aware of the level and type of assistance available to help support their pet in order to improve quality of life. Even though outcome can be hard to predict, such an approach ensures the most is being made of the opportunity and many cases will respond favorably, which can be a source of great satisfaction for all involved.


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  23. Bray EE, Raichlen DA, Forsyth KK, et al. Associations between physical activity and cognitive dysfunction in older companion dogs: results from the Dog Aging Project. Geroscience 2023;45:645-661. DOI: 10.1007/s11357-022-00655-8

Beverley M. Wilson

Beverley M. Wilson

Dr. Wilson graduated from the University of Nottingham in 2012 Read more

Daniel S. Mills

Daniel S. Mills

Professor Mills graduated from the University of Bristol in 1990 Read more

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Want to know how older cats differ in their nutritional needs from younger individuals? This article tells you what you need to know.

By Lori Prantil and Becca Leung

Issue number 33.3 Published 12/01/2024

How I approach… Gingival enlargement in the dog

Gingival enlargement in a dog‘s mouth is a common presentation in the exam room; this paper covers the common pathologies encountered and discusses the preferred approach to treatment.

By Christopher Sauvé