How to test aging and memory problems in dogs

Abstract

Companion dogs are a valuable model for aging research, including studies of cognitive decline and dementia. With advanced age, some dogs spontaneously develop cognitive impairments and neuropathology resembling features of Alzheimer's disease. These processes have been studied extensively in laboratory beagles, but the cognitive assays used in that context-which rely on time-consuming operant procedures-are not easily scalable to large samples of community-dwelling companion dogs. We developed a battery of five short-form tasks targeting three aspects of cognition that are impaired in Alzheimer's disease: spatial memory, executive functions, and social cognition. In Experiment 1, we tested a cross-sectional sample of dogs (N = 123) and estimated associations between age and task performance. Older dogs scored lower on measures of spatial learning, memory, and response flexibility, and spent less time near, but more time gazing at, the experimenter. We found no differences in associations between age and performance across dogs of different body masses, a proxy for expected lifespan. In Experiment 2, we demonstrated the feasibility of these measures in clinical settings (N = 35). Dogs meeting clinical criteria for moderate or severe cognitive impairment scored lower, on average, than dogs characterized as mildly impaired and healthy agers, although these distributions overlapped. However, few dogs in our study cohort met the criteria for moderate or severe impairment. The measures presented here show promise for deployment in large-scale longitudinal studies of companion dogs, such as the Dog Aging Project.