Obesity and sarcopenia affect the metabolite profiles of pet dogs

Overweight and reduced muscle mass significantly affect canine health, yet their metabolic implications in dogs require further investigation. This study aimed to characterize metabolic alterations associated with overweight, obesity, and reduced muscle mass in dogs. An observational, cross-sectional study was conducted to evaluate differences in metabolite concentrations among pet dogs with varying body and muscle conditions. Dogs older than two years were included in the Body Condition Score (BCS) analysis (n = 186), while only dogs older than eight years were included in the Muscle Condition Score (MCS) analysis due to age-related sarcopenia (n = 99). Metabolomic analyses were performed using a validated, canine-specific nuclear magnetic resonance (NMR) platform. Associations between metabolite concentrations and body or muscle condition were examined independently using generalized linear models, adjusting statistically for age and health status. Increasing overweight status correlated with notable disruptions in lipid and glucose metabolism, alongside elevated inflammation markers. Specifically, several lipid metabolites increased linearly with increasing overweight, as did citrate, lactate, pyruvate, and the inflammatory biomarker GlycA. Conversely, decreased muscle mass showed relatively modest independent metabolic effects, including elevated GlycA, an increased phenylalanine-to-tyrosine ratio, and alterations in VLDL subclass composition. Muscle mass was closely associated with age and overall health status, with health status emerging as the primary determinant of metabolite concentrations. Moderate to severe muscle loss was predominantly observed in dogs with underlying diseases. The metabolic consequences of overweight and sarcopenia, particularly increased inflammation common to both conditions, could significantly impact a dog's overall health. These findings reinforce existing evidence regarding the detrimental health effects associated with overweight and sarcopenia in dogs. Furthermore, the study suggests that underlying disease should be suspected in older dogs presenting highly abnormal metabolite profiles or moderate to severe muscle loss.