Cognitive dysfunction is a common medical condition in older dogs that results from abnormal brain function causing behavioural changes including disorientation, housebreaking problems, and changes in sleeping patterns and interactions with others. It is estimated that nearly 1 in 3 of dogs 11-12 years of age and nearly 3 in 4 dogs 15 years or older show at least one sign associated with Cognitive Dysfunction Syndrome (CDS). However, it is estimated that less than 5% of cases are being accurately diagnosed. Clinical signs may be overlooked by both clinicians and caregivers. Caregivers may not notice the subtle signs or do not think it necessary to discuss them, especially if they believe that their dog is experiencing normal signs of ageing or that nothing can be done. Educating is the key to addressing this issue and improving outcomes for the senior canine patient.
Cognitive processes include:
- Perception – become aware through the senses;
- Learning – acquiring knowledge through experience;
- Memory – encoding, storing and retrieving information.
Cognitive dysfunction syndrome is a neurobehavioural syndrome characterised by decline in cognitive processes sufficient to interfere will normal functioning with behaviour changes not attributable to other medical conditions. The prevalence of CDS in senior dogs is very high. Reportedly, 1 in 3 11-12-year-olds and 3 in 4 15-16-year-olds display at least one behavioural sign of CDS.
CDS is underdiagnosed because caregivers may accept behavioural changes as a normal sign of ageing and signs are difficult to evaluate in a clinical setting.
Senior pet checklists and surveys improve the early detection of CDS as well as help stage the severity of the disease. Screening patients 10 years or older as part of routine annual check-up allows for early treatment slowing the progress of CDS.
Access our CDS screening tool here:
Doggy Dementia Screening Tool Key:
Score 0-7 – Normal ageing
Score 8-23 – Mild cognitive impairment – please see your regular veterinarian.
Score 24-44 – Moderate cognitive impairment- Please see your regular veterinarian
Score 45-95 – Severe cognitive impairment – please see your regular veterinarian
What causes doggy dementia?
Aging is a whole body process, and changes in many systems can present with behavioural signs. Thorough clinical examination and appropriate diagnostic testing including complete blood profile, biochemistry panel, urinalysis and additional testing relevant to clinical findings (e.g. radiography, ultrasonography, specific blood test) is an essential first step.
CDS is a degenerative disease characterised by:
- Structural changes in the brain secondary to accumulation of protein (amyloid) plaques and loss of neurons. Structural changes result in loss of memory and irreversible impairment of higher cognitive functions. These brain changes are very similar to dementia and the early stages of Alzheimer’s disease in humans.
- Numerous vascular and perivascular changes occur including micro-bleeds and blood vessel blockage compromising blood flow causing brain tissue atrophy.
- Altered neurotransmitters (brain chemicals) including decreased dopamine (regulates reward and pleasure as well as emotional regulation and movement) levels.
- Meningeal (membrane covering of the brain) calcification, demyelination, glial changes, increasing amounts of lipofuscin and apoptotic bodies, neuroaxonal degeneration, and a reduction in neurons.
- Recent studies in humans, with different forms of age-related dementia, have found that anxiety, mood disorders, and agitation may increase as dementia worsens. These changes may be analogous to the agitation, distress, and anxiety (e.g., separation anxiety, aggression, irritability, vocalization, phobias, compulsive disorders, night waking) that are seen in some senior animals.
There is no known cure for CDS. Multiple therapeutic approaches have been used, with variable efficacy in improving cognitive function and/or slowing the progression of CDS.
The patient’s home environment needs to be adjusted to accommodate the patients changing needs and improve the feeling of safety and comfort. Feeding, drinking, toileting and sleeping resources need to be adjusted to improve accessibility. The daily routine should be predictable with increased daytime exercise to reduce nighttime waking.
Simple brain exercises in the form of food-based problem solving can help improve brain health as well as provide a focus away from anxiety-based behaviours.
Signals previously used in training may need to be adjusted to accommodate the patients changing sensory ability. Using tactile cues or hand signals are frequently more consistent and easier for the patient to understand. Short, frequent training sessions using positive reinforcement with high-value food rewards also promote brain health and add to daily enrichment.
- Antioxidants : diets fortified with antioxidants, mitochondrial cofactors, and omega-3 fatty acids have proven beneficial.
- S-Adenosyl-l-Methionone (Denosyl): synthesised by the liver and other cells in the body sAME is essential for healthy liver function. sAME increases production of antioxidants which results in increased serotonin (mood chemical) turnover and increased dopamine and norepinephrine levels.
- Medium-chain Triglycerides: assists in energy production for brain functioning result in improved cognitive function. E.g. virgin coconut oil (1-2 g/kg/day)
- Phosphatidylserine: a natural phospholipid in cell membranes found in high concentration at synapses. Treatment may improve memory and learning.
- Apoaequin: neuroprotective effects which results in improved learning and attention.
- Micronutrients such as Magnesium, Vitamin E, Selenium and Zinc act as cofactors in several neuronal metabolic processes improving neuronal development and neurotransmission and have improved neuroplasticity (ability of the brain to improve neuropathways and neuron and synaptic connections).
- Selegiline – helps to increase production of neurotransmitters including dopamine.
- Propentofylline This drug improves blood flow to the brain via vasodilation and reducing blood viscosity.
- Adrafanil and modafinil may have some benefit in increasing alertness, memory, and learning but more research is needed.25
- Physical therapy
Other proposed treatments that have been suggested but have not been clinically tested include the following:
- Anti-inflammatory drugs may be of benefit since inflammatory changes have been identified in the brains of dogs with CDS.
- Some experimental evidence indicates that certain naturally-occurring phytochemicals (e.g. curcumin, green tea catechins, resveratrol) may have therapeutic potential for CDS via their anti-oxidant activity and their ability to decrease amyloid in the brain.
- Complementary therapies may calm the patient, reduce anxiety, and normalize the sleep-wake cycle but the evidence for efficacy of the following is entirely anecdotal: melatonin, valerian root, dog-appeasing pheromone (DAP), phosphatidylserine, ginkgo biloba, DHA (an omega 3 fatty acid), various antioxidants, and mitochondrial co-factors.3
If you want to know more or if you think your companion may be suffering cognitive dysfunction please get in touch. We can help you!
- Neurobiology of the aging dog.Head E. Age (Dordr) 33:485-496, 2011.
2. Beta-amyloid accumulation correlates with cognitive dysfunction in the aged canine. Cummings BJ, Head E, Afagh AJ, et al. Neurobiol Learn Mem 66:11-23, 1996.
3. Dogs with cognitive dysfunction syndrome: A natural model of Alzheimer’s disease. Bosch MN, Pugliese M, Gimeno-Bayón J, et al. Curr Alzheimer Res 9:298-314, 2012.
4. Prevalence of behavioral changes associated with age-related cognitive impairment in dogs.Neilson JC, Hart BL, Cliff KD, Ruehl WW. JAVMA 218:1787-1791, 2001.
5. Beta-amyloid deposition and tau phosphorylation in clinically characterized aged cats. Head E, Moffat K, Das P, et al. Neurobiol Aging 26:749-763, 2005.
6. Visuospatial function in the beagle dog: An early marker of cognitive decline in a model of human aging and dementia. Studzinski CM, Christie LA, Araujo JA, et al. Neurobiol Learn Mem 86:197-204, 2006.
7. Prevalence and risk factors of behavioral changes associated with age-related cognitive impairment in geriatric dogs. Azkona G, García- Belenguer S, Chacón G, et al. J Small Anim Pract 50:87- 91, 2009.
8. Clinical signs and management of anxiety, sleeplessness, and cognitive dysfunction in the senior pet. Landsberg GM, Deporter T, Araujo JA. Vet Clin North Am Small Anim Pract 41:565-590, 2011.
9. Assessment of nutritional interventions for modification of age-associated cognitive decline using a canine model of human aging. Araujo JA, Studzinski CM, Head E, et al. Age(Dordr) 27:27-37, 2005.
10. Dietary supplementation with medium-chain TAG has long-lasting cognition-enhancing effects in aged dogs. Pan Y, Larson B, Araujo JA, et al. Br J Nutr 103:1746-1754, 2010.
11. NOVIFIT (NoviSAMe) tablets improve executive function in aged dogs and cats: Implications for treatment of cognitive dysfunction syndrome. Araujo JA, Faubert ML, Brooks ML, et al. Int J Appl Res Vet Med 10:90-98, 2012.
12. Improvement of short-term memory performance in aged beagles by a nutraceutical supplement containing phosphatidylserine, Ginko biloba, vitamin E, and pyridoxine. Araujo JA, Landsberg GM, Milgram NW, Miolo A. Can Vet J 49:379-385, 2008.