Clinical and neuropathological aspects of canine cognitive dysfunction syndrome and a translational perspective for Alzheimer's disease.

Canine cognitive dysfunction syndrome (CCDS) shares notable clinical and molecular similarities with Alzheimer's disease (AD), supporting the value of cross-species translational research to enhance diagnostic and therapeutic approaches for both conditions. These disorders are progressive neurological diseases characterized by abnormal accumulation of neurotoxic proteins, primarily amyloid-β and tau. Their pathological aggregation induces neural injury and cerebral dysfunction, culminating in comparable clinical manifestations in dogs and humans. Exosomal microRNAs represent a promising class of molecular biomarkers for early diagnosis and provide insights into disease progression. Current diagnostic strategies include neurological evaluation, advanced imaging techniques, and, in dogs, behavioral assessments based on owner-reported observations. These assessments employ standardized rating scales such as the Canine Cognitive Dysfunction Rating Scale, the Canine Dementia Scale, and the DISHA questionnaire, which evaluate key signs of CCDS, including disorientation, altered interactions, sleep-wake cycle disturbances, house-soiling, and anxiety. This review highlights advances in understanding AD and canine cognitive dysfunction syndrome, linking veterinary and human medicine to foster translational insights benefiting both fields.