Steaming hay significantly reduces respirable particles and provides a palatable alternative to dry hay for horses with asthma. However, few prospective studies demonstrate the clinical efficacy of steamed hay. This controlled crossover study aimed to compare the efficacy of alfalfa pellets and steamed hay in improving lung function and inflammation in horses with severe equine asthma (SEA).
Study Population
Ten horses with SEA were enrolled, and nine completed the study. Horses were housed indoors and fed hay. Once in exacerbation, they were fed pellets and steamed hay for four weeks in a crossover design. Researchers recorded weighted clinical scores and lung function weekly. Bronchoalveolar lavage fluid (BALF) cytology and mucous scores were recorded before and after each diet.
Results
Based on linear mixed model (LMM) analysis, weighted clinical scores improved significantly over time (p < 0.001, no diet effect or time-diet interactions). With pellets, weighted clinical scores decreased from (median (interquartile range)) 13 (5.5) to 2 (1.5), while with steamed hay, they decreased from 10 (9.5) to 6 (8.5). With pellets, lung resistance decreased significantly from a baseline of (mean (SD)) 2.62 (0.77) cmH2O/L/s to 1.17 (0.66), 0.79 (0.54), 0.70 (0.20), 0.62 (0.18) on Weeks 1-4, respectively (LMM with post hoc tests, p < 0.001). With steamed hay, resistance decreased significantly from a baseline of 2.34 (0.93) cmH2O/L/s to 1.38 (0.49) and 1.51 (0.66) on Weeks 1 and 2, respectively (p < 0.03). Neutrophils BALF decreased significantly with both diets (pellets: 40.2 (24.4) to 20.1 (11.0) %; steamed hay 30.9 (20.2) to 25.7 (17.6) %; LMM, p = 0.006).
Bottom Line
Clinical 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.
https://beva.onlinelibrary.wiley.com/doi/10.1111/evj.14209
Related Reading
- Diagnosing Respiratory Ailments in Horses: Wash or Lavage?
- Managing Severe Equine Asthma
- Equine Asthma and Obesity
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