Recognizing Signs of Cognitive Dysfunction

Canine cognitive dysfunction (CCD) shows similarities to human Alzheimer’s disease (AD), including changes in behavior and daily routines, the accumulation of amyloid beta in the brain, and a likely role of oxidative stress. The aim of this study was to investigate CCD clinical characteristics, survival, and risk factors. Vitamin E was measured as a possible CCD marker. Owners of 94 dogs over 8 years of age were interviewed using a validated CCD questionnaire, focusing on behavior changes related to disorientation, socioenvironmental interaction, sleep-wake cycle, housesoiling, drinking, appetite, and aggression. Dogs were scored into 3 groups: non-CCD, borderline CCD, and CCD. Additional questions addressed signs of anxiety and abilities associated with learning and memory, given the frequency of these signs in AD and its precursor, mild cognitive impairment (MCI). Dogs were examined, then followed in an observational study until a final owner interview 3–4 years later.

Four key signs prevailed in CCD dogs: daytime sleeping with nighttime restlessness, decreased interaction, disorientation at home, and anxiety. Some borderline cases developed CCD over time, indicating a possible prodromal stage similar to MCI, with the predominant sign being sleep changes. Vitamin E levels did not differ between groups. CCD did not negatively influence survival.

Global CommentaryAlthough there are many signs of CCD, this study identified the 4 most prevalent. The authors also found that a prodromal stage (ie, borderline CCD) could be equated with MCI in humans and is considered a risk factor for developing dementia (eg, Alzheimer’s disease).

Dogs with any anxiety disorder are not only stressed but often distressed, and anxiety may decrease life expectancy in humans and dogs. Early recognition and treatment of CCD and borderline CCD are imperative to increasing patient welfare. Using anxiolytic medication in my older canine patients has proven beneficial for dogs and their human companions to improve the quantity and, more importantly, the quality of their lives.—Kersti Seksel, BVSc (Hons), MRCVS, MA (Hons) FACVSc

SourceAn observational study with long-term follow-up of canine cognitive dysfunction: Clinical characteristics, survival, and risk factors. Fast R, Schütt T, Toft N, et al. JVIM 27:822-829, 2013.

This capsule is part of the One Health Initiative and the Global Edition of Clinician's Brief