Effect of nutritional antioxidant supplementation on systemic and pulmonary antioxidant status, airway inflammation and lung function in heaves-affected horses.
Authors: Kirschvink N, Fiévez L, Bougnet V, Art T, Degand G, Smith N, Marlin D, Roberts C, Harris P, Lekeux P
Journal: Equine veterinary journal
Summary
# Editorial Summary Chronic inflammatory airway disease in horses involves an oxidative imbalance that drives pathological inflammation, raising the question of whether targeted nutritional antioxidant support might improve clinical outcomes. Eight clinically remissive heaves cases received either a four-week course of mixed antioxidants (vitamins E and C combined with selenium) or placebo in a randomised, blinded design, with researchers measuring lung function, exercise tolerance, airway inflammation via endoscopy and bronchoalveolar lavage, alongside systemic and pulmonary biomarkers of oxidative stress including uric acid, glutathione and 8-epi-PGF₂α. The supplemented group demonstrated significantly improved exercise tolerance and reduced endoscopic airway inflammation scores, whilst plasma uric acid concentrations dropped meaningfully—indicating suppression of xanthine oxidase activity—though pulmonary function parameters and BAL cytology showed no significant changes. Whilst these findings suggest antioxidant supplementation can modulate the oxidant/antioxidant balance and clinical airway inflammation in heaves-affected horses, the lack of corresponding improvements in objective lung function or pulmonary biomarkers warrants caution in interpreting clinical significance; practitioners should consider this as a potentially useful adjunctive therapy for managing clinical signs rather than as a mechanism-specific intervention targeting pulmonary oxidative stress.
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Practical Takeaways
- •A 4-week course of antioxidant supplementation (vitamins E and C with selenium) may improve ridden exercise tolerance and reduce visible airway inflammation in horses recovering from heaves episodes
- •Systemic antioxidant markers respond more reliably to supplementation than pulmonary markers, suggesting benefit is measurable even when BAL cytology appears unchanged
- •Antioxidant supplementation appears to work by modulating oxidant/antioxidant imbalance rather than directly clearing existing inflammatory cells from airways
Key Findings
- •Antioxidant supplementation significantly improved exercise tolerance in heaves-affected horses
- •Endoscopic inflammatory airway score was significantly reduced with antioxidant treatment
- •Plasma uric acid concentrations significantly decreased, indicating downregulation of oxidant-producing pathways
- •Pulmonary lining fluid markers and bronchoalveolar lavage cytology showed no significant changes despite systemic improvements