Steamed hay is fed as part of the management of equine asthma. This experiment fed steamed hay in a cross-over in vivo study design. It measured the lung function, bronchoalveolar lavage fluid (BALF) cytology and a weighted clinical score before and after 4 weeks of feeding. The researchers concluded that "[s]teamed hay induced a mild but significant deterioration of lung function and inflammation in horses with severe equine asthma [SEA]."

The results of this study highlight the inconsistent benefits of feeding steamed hay for the management of equine asthma. A companion manuscript published in May 2025 (Symoens et al.) found that "[c]linical scores, lung function and BALF inflammation of horses with SEA improved with steamed hay and pellets, but the effect on lung function was more pronounced with pellets."