Cognitive dysfunction syndrome (CDS) results from irreversible degeneration of the brain beyond normal aging, including changes in brain glucose metabolism.
The impairments with CDS are more severe than those seen with normal aging processes or cognitive decline, despite some overlap of behavioral signs with the latter. CDS may lead to severe memory loss and learning difficulties, comparable to Alzheimer’s disease in humans. Although the onset of CDS is often insidious, it may appear sudden to owners and may change their relationship with their pet from ‘best friends’ to ‘caregiver and patient’. Owners may feel anxious and want to know that they are doing all they can to prevent or manage CDS.
CDS affects an estimated 14% of dogs 8 years and older (with increasing prevalence with age), but is under-diagnosed by veterinarians.1 Purina has developed a tool to help veterinarians diagnose CDS and monitor its progression in dogs. Purina’s research has shown that nutritional strategies can help slow progression of CDS in dogs by targeting risk factors of age-related neurodegeneration.
The behavioral signs of CDS are non-specific and may be initially dismissed by owners as inevitable with age. CDS can mimic the clinical signs associated with a number of health conditions, including osteoarthritis, thyroid disease, metabolic disorders, neoplasia, and kidney disease. The presence of concurrent disease can worsen cognitive impairment or dysfunction. CDS is often a diagnosis of exclusion.
Many of the behaviors seen with cognitive dysfunction overlap with those seen in cognitive decline. The DISHAA tool was developed to help veterinarians distinguish between the two. The tool is a questionnaire that can be completed by owners or by the veterinary staff in consultation with owners, which separates behaviors into categories: Disorientation; Social Interactions; Sleep/Wake Cycles; House soiling, Learning and Memory; Activity; and Anxiety. The assessment can be used to support presumptive diagnosis of CDS and to monitor the dog over time. The number, frequency and severity of the signs observed, as well as the change over time, indicate the level of impairment and trajectory of decline. For a diagnosis of CDS, more than 1 cognitive domain must be affected. For example, CDS may be suspected in a dog that demonstrates impairment in the Interactions (I) and Anxiety (A) categories on the DISHAA questionnaire, but a dog impaired only in the Interactions (I) category would be considered to have cognitive impairment. For the second dog, the DISHAA assessment acts as a baseline for assessing progression toward CDS.
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.2
In a double-blind clinical trial, dogs with confirmed CDS who were fed a diet containing MCTs and brain-protecting nutrients showed significant improvement in 5/6 DISHAA categories in as little as 30 days, with noticeable improvement in 6/6 DISHAA categories by 90 days.3
1. 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.
2. 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
3. Pan, Y., Landsberg, G., Mougeot, I., Kelly, S., Xu, H., Bhatnagar, S., Migram, N.W. (2017). Efficacy of a therapeutic diet in dogs with signs of cognitive dysfunction syndrome (CDS): a prospective, double-blinded, placebo-controlled clinical study. Abstract N10: 2017 American College of Veterinary Internal Medicine (ACVIM) forum. Available at https://onlinelibrary.wiley.com/doi/epdf/10.1111/jvim.14778