Nutrition and the ageing canine brain

Much like in humans, our dogs’ brains develop metabolic, functional and physical changes with age. Many of these are unwanted and can lead to changes in the behaviour of senior dogs. Even observant pet owners may not recognise signs of cognitive decline until there’s a sudden change in their pet’s behaviour with studies showing that mild cognitive impairment can be detected in apparently normal dogs as early as 6 years old (1). Fortunately, there are things we can do to help, including providing the right nutrition. 

What happens in the aging brain? (2-3)

• Regional atrophy (shrinkage) of brain tissue with increasing volume of the fluid filled ventricles

• Loss of neurons and synapses and reduced formation of new neurons

• Accumulation of abnormal proteins

• Less able to effectively utilise glucose as an energy source. There is significant reduction in glucose use in the frontal cortex and hippocampus, two areas critical for cognitive function

• Chronic inflammation and increases in toxic free radicals

• Vascular changes

• Deterioration in the myelin sheaths of neurons

• Abnormalities of astrocytes and neuron-supporting cells

• Impaired clearance of abnormal proteins

• Alterations in gene expression

What are the signs? 

In many pets, age-related cognitive decline doesn’t affect day-to-day functions and can only be detected through regular cognitive function testing such as the Canine Cognitive Assessment Scale (CCAS) or Canine Dementia Scale (CADES). In other dogs, the changes are obvious and similar to dementia in people, known as cognitive dysfunction syndrome (CDS). CDS has a slow onset, can be difficult to manage and affects around 14% of dogs 8 years and older(4).

The behavioural signs of CDS are non-specific so may be dismissed as normal aging if cognitive function isn’t tested regularly. Age-related cognitive decline and CDS exist on a spectrum, so their clinical signs overlap. CDS can also mimic the signs of other health conditions, and it is often a diagnosis of exclusion, meaning that other problems need to be ruled out first. 

The key clinical signs seen in CDS can be classified into different cognitive domains under the acronym, DISHAA. See Table 1. 

What can we do to help? 

Dogs with cognitive dysfunction are likely to benefit from multimodal management including nutrition, medication, exercise, environmental modification and enrichment, and more. 

By providing the right nutrition, we can target some of the known age-related brain changes. Key nutrients include:

Ketones from medium-chain triglycerides (MCTs)

With age, the brain’s ability to use glucose as an energy source declines, and due to its high energy demands, it is particularly vulnerable to an inadequate energy supply resulting from altered energy metabolism. Reduced glucose metabolism may start a chain reaction that eventually leads to cell death and irreversible loss of mass. Fortunately, ketones can be used as an alternative energy source by the brain, and ketone metabolism appears unaffected by age. Ketone bodies can provide 60-70% of the brain’s energy during fasting and low glucose availability (5).

Ketones have additional benefits beyond being a source of energy. They decrease production of reactive oxygen species that cause oxidative stress; encourage the formation of new mitochondria (the cell’s powerhouse); and stimulate the synthesis of useful polyunsaturated fatty acids. They may also help restore mitochondrial function and stimulate pathways that help clear abnormal proteins.

Traditional ketogenic diets used in humans are less appropriate for dogs, instead, dietary MCTs can be provided which are converted into ketones by the liver. Though MCTs are found in botanical oils such as coconut oil, it is worth noting that high concentrations of the most ketogenic fatty acids, C8 and C10 (rather than C 12) (6-7),  are not found naturally. An oil that has been processed to maximise the C8/10 fractions, is a better option.

Purina research has shown that senior dogs fed a diet containing medium-chain triglycerides (MCTs) made fewer errors on cognitive tests assessing awareness, perception, reasoning, and adaptability, with improvement in memory observed within 2 weeks. In contrast to dogs on the control diet, senior dogs fed the MCT diet also performed better as the cognitive tasks became harder.

In a clinical study, a diet with 6.5% MCTs and a specific "Brain Protection Blend" – including B vitamins, antioxidants, omega-3 and arginine – was able to significantly improve all six categories of CDS signs in dogs in 90 days, with improvements in five of the categories visible after 30 days (9).

Other useful nutrients include

• Antioxidants: the body produces its own antioxidants, but its capacity decreases with age, along with an increase in the production of free radicals. Antioxidants scavenge free radicals to reduce the damage they can cause. With age, an imbalance can occur causing oxidative stress. Dietary antioxidants may help reestablish the balance

• Fish oil: an excellent source of omega-3 fatty acids, particularly DHA and EPA. These play critical neuroprotective and anti-inflammatory roles. 

• Arginine: metabolised by cells, including neurons, to form nitric oxide. Nitric oxide is the primary mediator that increases regional blood flow within the brain in response to higher neural activity during cognitive tasks. It is also metabolised to the neurotransmitter, agmatine. 

• B vitamins: thiamine (B1), pyridoxine (B6), folate (B9), and cobalamin (B12) are particularly important for neurodevelopment and cognitive function. B vitamin deficiency can lead to elevated blood levels of the amino acid homocysteine, which is a risk factor for cognitive impairment. 

PURINA® PRO PLAN® NC NeuroCare™ provides complete and balanced nutrition for adult and senior dogs to support brain function and age-related cognitive decline. It is intended for use under veterinary supervision so pet owners should consult their vet before use. 

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© Nestlé Purina Petcare 2025

References

1 Studzinski, C. M., Christie, L.-A., Araujo, J. A., Burnham, W. M., Head, E., Cotman, C. W., & Milgram, N. W. (2006). Visuospatial function in the beagle dog: an early marker of cognitive decline in a model of human aging and dementia. Neurobiology of Learning and Memory, 86, 197–204

2  London, E. D., Ohata, M., Takei, H., French, A. W., & Rapoport, S. I. (1983). Regional cerebral metabolic rate for glucose in beagle dogs of different ages. Neurobiology of Aging, 4, 121–126

3  Schütt, T., Toft, N., & Berendt, M. (2015). Cognitive function, progression of age-related behavioral changes, biomarkers, and survival in dogs more than 8 years old. Journal of Veterinary Internal Medicine, 201, 1569–1577. doi: 10.1111/jvim.13633

4  Salvin, H. E. McGreevy, P. D., Sachdev, P.S., & Valenzuela, M. J. (2010). Under diagnosis of canine cognitive dysfunction: a cross-sectional survey of older companion dogs. Veterinary Journal, 184, 277–281

5 Nugent, S., Tremblay, S., Chen, K. W., Ayutyanont, N., Roontiva, A., Castellano, C.-A. & Cunnane, S. C. (2014). https://www.ncbi.nlm.nih.gov/pubmed/24388785 Brain glucose and acetoacetate metabolism: a comparison of young and older adults. Neurobiology of Aging, 35, 1386–1395. doi: 10.1016/j.neurobiolaging.2013.11.027

6 Tetrick MA, Greer FR, Benevenga NJ. (2010) Blood D-(-)-3-hydroxybutyrate concentrations after oral administration of trioctanoin, trinonanoin, or tridecanoin to newborn rhesus monkeys (Macaca mulatta). Comp Med. Dec; 60(6):486-90.

7  Sato H. (1994) Plasma ketone levels in neonatal calves fed medium chain triglycerides in milk. J Vet Med Sci. Aug; 56 (4):781-2.

8  Pan, Y., Larson, B., Araujo, J. A., Lau, W., de Rivera, C., Santana, R., ...Milgram, N. W. (2010). Dietary supplementation with medium-chain TAG has long-lasting cognition-enhancing effects in aged dogs. British Journal of Nutrition, 103, 1746–1754. doi: 10.1017/S0007114510000097

9 Pan Y, et al. (2018) Efficacy of a Therapeutic Diet on Dogs With Signs of Cognitive Dysfunction Syndrome (CDS): A Prospective Double Blinded Placebo Controlled Clinical Study. Front Nutr. Dec 12;5:127.