Recurrent Airway Obstruction and Inflammatory Airway Disease
Authors: Wilson M. Eilidh, Robinson N. Edward
Journal: Robinson's Current Therapy in Equine Medicine
Summary
# Editorial Summary: Fungal Contamination and Inflammatory Airway Disease in Horses Fungi have long been implicated in recurrent airway obstruction (RAO) in horses, yet their role in the milder inflammatory airway disease (IAD) remained unclear until Wilson and Robinson's prospective analysis of 731 performance and sport horses presenting with respiratory signs or poor performance. Using tracheal wash cytology, fungal culture, and bronchoalveolar lavage, the researchers identified positive fungal cultures in 55% of cases, with horses displaying fungal elements on cytology demonstrating a twofold increased odds of IAD diagnosis (OR 2.1). Environmental management proved critical: straw bedding and dry hay feeding both approximately doubled the risk of IAD development (OR 2.0–2.7) and fungal airway colonisation (OR 1.9–2.6). These findings suggest that fungal inhalation represents a significant and potentially modifiable risk factor in IAD aetiology, with substantial practical implications for stable design, forage selection, and bedding choices—particularly for horses with performance limitations or clinical signs suggestive of lower airway inflammation. For farriers, vets, and allied equine professionals, this evidence strengthens the case for recommending haylage or other low-dust forage alternatives and dust-minimisation strategies when managing horses with suspected or confirmed IAD.
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Practical Takeaways
- •Switch horses with respiratory disease or poor performance from straw bedding and dry hay to alternative forage and bedding materials (e.g., shavings, haylage) to reduce fungal exposure and IAD risk
- •Consider fungal contamination as a likely contributor when investigating respiratory signs in performance horses, particularly those on traditional straw and dry hay management
- •Environmental and nutritional management changes may be as important as medical treatment for managing IAD in horses with documented fungal airway colonization
Key Findings
- •Positive fungal culture obtained in 55% (402/731) of horses with respiratory disease or poor performance
- •Horses with fungal elements on tracheal wash cytology had 2.1 times greater odds of IAD diagnosis compared to horses without fungi (P = 0.0003)
- •Straw bedding increased odds of IAD (OR = 2.0) and fungal airway presence (OR = 1.9)
- •Dry hay feeding significantly increased odds of IAD (OR = 2.7) and fungal contamination (OR = 2.6)