Abstract
INTRODUCTION: Canine Cognitive Dysfunction (CCD) is an increasingly prevalent naturally occurring neurodegenerative condition in senescent dogs that share neuropathological and clinical features with human Alzheimer's disease (AD). Metabolic profiling allows for identification of new candidates for AD biomarkers, diagnostics, and therapeutics. Despite its translational potential, plasma metabolomic profiling of dogs with CDD has not been previously characterized. METHODS: This case-control study analyzed plasma samples from ten client-owned geriatric dogs, including five with severe CCD and five age-matched, clinically healthy controls. Untargeted plasma metabolomics was performed using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Multivariate and univariate statistical analyses identified significant metabolic differences between the groups. Metabolites were considered significant based on a variable importance in projection (VIP) score > 1.5, fold change (FC) > 2.0, and adjusted p-value <0.05. RESULTS: Fifteen metabolites across seven chemical classes were significantly altered in CCD dogs compared to controls, including glycerophospholipids, steroid derivatives, indoles, and mitochondrial-related compounds. Notably, elevated lysophosphatidic acid (LPA 20:2/0:0) and reduced ubiquinone-2 levels suggest dysregulation in neuroinflammatory and oxidative stress pathways. Cholesterol exhibited the highest FC and VIP scores, further reinforcing its role in AD pathogenesis. Hierarchical clustering and pathway enrichment analyses supported distinct metabolic signatures in CCD that mirror those observed in human AD. DISCUSSION: This is the first untargeted plasma metabolomic profiling of dogs with CCD, revealing systemic metabolic disturbances that align with AD pathophysiology. Data was collected from senescent community-dwelling companion dogs, which enhances the study's ecological and translational relevance. It supports the utility of CCD as an AD model and highlight candidate plasma biomarkers that warrant further investigation. Future longitudinal studies integrating metabolomics with neuroimaging, histopathology, and behavioral assessments are required to validate these findings and contribute to AD biomarker discovery and therapeutic development.