Evaluation of Cognitive Function in the Dog Aging Project: Associations with Baseline Canine Characteristics

Background Canine Cognitive Dysfunction (CCD) is a neurodegenerative disease in aging canines. It has been described previously in relatively small cohorts of dogs using multiple different rating scales. This study aimed to use a minimally modified CCD rating scale developed by previous researchers to describe the prevalence of CCD more thoroughly in a large, nationwide cohort of companion dogs known as the Dog Aging Project (DAP). Specifically, associations between various canine characteristics, predicted life stage quartiles, and CCD were examined.
Methods This study used baseline data collected from October 30, 2020 to December 31, 2020 from 15,019 dogs enrolled in the DAP, a nationwide longitudinal study on canine aging and mortality in US companion dogs. Two surveys, the Canine Social and Learned Behavior Survey (CSLB) and the Health and Life Experience Survey (HLES), which provided owner-reported information on various canine characteristics and classified dogs as having probable CCD, were used. Associations were assessed using univariable and multivariable logistic regression models adjusted for age, sterilization status, history of 15 categories of health problems, breed type, and activity level. Associations between predicted life stage quartile and CCD were also assessed, and life stage quartile was evaluated for its predictive ability through adjusted and unadjusted logistic regression models. Predictive capacity of these models was quantified using the area under the curve of a constructed Receiver Operating Curve (ROC).
Results When controlling for all other characteristics, the odds of CCD increased 52% with each additional year of age (OR=1.52, 95% CI 1.44, 1.61). Among dogs of the same age, health status, breed type, and sterilization status, odds of CCD was 6.47 times higher in dogs who were not active compared to those who were very active (OR=6.47, 95% CI 2.93-17.23). When controlling for age, breed type, activity level, and other comorbidities, dogs with a history of
neurological, eye, or ear disorders had higher odds of CCD (OR=1.84, 95% CI 1.26, 2.65; OR=2.16, 95% CI 1.57, 2.98; OR=1.96, 95% 1.42, 2.70, respectively). The diagnostic threshold of CSLB score ≥ 50 (which corresponded with positive CCD status) had excellent predictive capacity for CCD (AUC=0.884).
Conclusions There existed a positive association between dog age and CCD. Positive associations between neurological, ear, or eye disorders and CCD, as well as an inverse association between physical activity and CCD, were also identified. Finally, canine life stage showed excellent discriminating ability between CCD positive and negative dogs. Quartile estimation could therefore serve as a tool to inform CCD screening by veterinarians.