Oxidative stress in critically ill neonatal foals.

Background: Oxidative injury occurs in septic people, but the role of oxidative stress and antioxidants has rarely been evaluated in foals.
Objectives/hypothesis: To measure reactive oxygen species (ROS), biomarkers of oxidative injury, and antioxidants in neonatal foals. We hypothesized that ill foals would have higher blood concentrations of ROS and biomarkers of oxidative injury and lower concentrations of antioxidants compared to healthy foals.
Animals: Seventy-two hospitalized and 21 healthy neonatal foals.
Methods: Prospective cohort study. Reactive oxygen species (hydrogen peroxide [H ₂ O ₂ ]), biomarkers of oxidative injury (malondialdehyde [MDA], protein carbonyl), and antioxidants (superoxide dismutase [SOD], catalase [CAT], glutathione, and glutathione reductase [GR] and peroxidase [GPx]) were measured from foals at admission. Measured variables were compared between healthy and ill foals using a 1-way ANOVA by Tukey's multiple comparisons test.
Results: Ill foals (n = 51) had significantly higher mean concentrations of H ₂ O ₂ (healthy 2.6 ± 1.4 nmol/mL, ill 6.8 ± 4.6 L nmol/mL; 95% CI), MDA (healthy 31.2 ± 14.4 nmol/mL, ill 114.3 ± 94.0 nmol/mL; 95% CI), and protein carbonyl (healthy 0.07 ± 0.01 nmol/mg protein, ill 0.12 ± 0.02 nmol/mg protein, 95% CI). Significant lower CAT (healthy 0.4 ± 0.3 mU/mg protein, ill 0.02 ± 0.02 mU/mg protein, 95% CI), glutathione (healthy 238.5 ± 101.9 μg/mL, ill 110.7 ± 37.8 μg/mL, 95% CI; P < .0001), GR (healthy 1.6 ± 1.8 mU/mg protein, ill 0.4 ± 0.5 mU/mg protein, 95% CI), and GPx (healthy 0.01 ± 0.003 mU/mg protein, ill 0.007 ± 0.002 mU/mg protein, 95% CI) were also noted.
Conclusions and Clinical Importance: Oxidative stress and lower antioxidant concentrations occur in ill and bacteremic neonatal foals. These variables should be considered during the treatment of ill foals.
(© 2025 The Author(s). Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)