Bindi_2026_J.Vet.Intern.Med_40_

BACKGROUND: Oxidative stress both contributes to and results from sepsis pathophysiology, but its role in ill foals remains poorly characterized. HYPOTHESIS/OBJECTIVES: Ill foals will exhibit decreased antioxidant defense activity and increased oxidative products compared with healthy foals, and these changes will be associated with higher sepsis scores, lower survival scores, and non-survival. ANIMALS: Twenty-six foals < 14 days old: 16 hospitalized foals (11 sick non-septic, 5 septic; median age, 1.5 days; range 1-13) and 10 healthy Standardbred foals (2 days old). Nine of 16 ill foals survived to discharge. METHODS: Prospective multicenter cohort study. Ill foals were sampled at admission and every 24 h; healthy foals were sampled once at 48 h. Plasma paraoxonase (POase), arylesterase (AREase), superoxide dismutase (SOD), butyrylcholinesterase (BTChE), glutathione S-transferase (GST), glutathione peroxidase (GPx), total antioxidant capacity (TAC), and lipid peroxidation (LPO) were measured. Associations with sepsis score, survival score, and outcome were evaluated using generalized linear mixed models. RESULTS: At admission, ill foals had lower SOD, GPx, BTChE, and GST and higher LPO compared with healthy foals (P >= .01). Non-survivors had lower POase (P = .01), SOD (P = .04), BTChE (P < .001), GST (P = .04), and GPx (P = .01) and higher LPO (P = .01). In mixed models, SOD, BTChE, and TAC were associated with both sepsis and survival score (P < .001). Arylesterase and POase were associated with sepsis score (P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: Ill neonatal foals had decreased antioxidant activity and increased oxidative products. Some biomarkers were associated with clinical scores and outcome, supporting further investigation of their potential clinical relevance.