Effect of chronic airway inflammation and exercise on pulmonary and systemic antioxidant status of healthy and heaves-affected horses.
Authors: Kirschvink N, Smith N, Fiévez L, Bougnet V, Art T, Degand G, Marlin D, Roberts C, Génicot B, Lindsey P, Lekeux P
Journal: Equine veterinary journal
Summary
# Editorial Summary Equine recurrent airway obstruction (RAO, commonly termed "heaves") involves complex interactions between airway inflammation, oxidative stress, and pulmonary dysfunction, yet the precise relationships between these factors remain poorly characterised. Kirschvink and colleagues compared antioxidant status in blood and pulmonary epithelial lining fluid (PELF) across healthy horses (n=6), RAO-affected horses in clinical remission (n=6), and those experiencing acute crisis (n=7), measuring glutathione ratios, uric acid, and lipid peroxidation markers both at rest and during standardised exercise. Crucially, they demonstrated that glutathione redox ratios in PELF increased significantly during acute RAO crisis and correlated directly with markers of airway inflammation (bronchoalveolar lavage neutrophil percentages and inflammatory scores); exercise-induced plasma uric acid elevation was markedly higher in both remission and crisis groups compared with healthy controls, and 8-epi-PGF2α (a lipid peroxidation biomarker) in PELF was substantially elevated during crisis states. The findings indicate that oxidative stress represents not merely an incidental feature of RAO but an integrated component of disease pathophysiology, with local pulmonary biomarkers (particularly PELF glutathione status and 8-epi-PGF2α) offering more sensitive assessment of airway inflammation than systemic markers alone. For practitioners, this suggests that management strategies targeting antioxidant capacity—through nutritional or pharmacological intervention—warrant consideration as adjunctive therapies, whilst PELF sampling may ultimately provide diagnostic precision superior to conventional approaches in distinguishing disease states.
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Practical Takeaways
- •Oxidative stress is a measurable component of heaves pathology; monitoring antioxidant status via blood glutathione in resting horses and uric acid in exercising horses may help assess disease severity
- •Heaves-affected horses show exaggerated oxidative stress responses to exercise, suggesting careful management of work intensity during crisis phases
- •Local airway inflammation in heaves produces distinct oxidative stress signatures in lung fluid that differ from systemic markers, indicating both local and systemic involvement of the disease process
Key Findings
- •Haemolysate glutathione differed significantly between healthy, remission, and crisis heaves groups and correlated with pulmonary function and airway inflammation parameters
- •Glutathione redox ratio in pulmonary epithelial lining fluid was elevated during heaves crisis and correlated with both pulmonary function and airway inflammation
- •Exercise-induced plasma uric acid increase was significantly higher in both remission and crisis heaves groups compared to healthy controls
- •PELF 8-epi-PGF2alpha was significantly elevated in crisis heaves and correlated with pulmonary function and airway inflammation parameters