News Notes

Steaming Hay and Alfalfa Pellets Effective for Asthma

A new study reinforces a common recommendation for equine asthma—steaming the hay or alfalfa pellets.
Researchers found that steaming significantly reduced inhaled particles, and the steamed product was still a palatable substitute for dry hay.

In this controlled, crossover study, the researchers compared the effectiveness of alfalfa pellets and steamed hay in improving lung function and reducing inflammation in horses with severe asthma (SEA) because they said there were limited data about this fairly common practice.

They enrolled 10 horses with SEA, and 9 completed the study: 5 mares and 4 geldings. The horses were between 15 and 22 years old. Despite the small sample size, several breeds were represented: 5 Quarter Horse or Quarter Horse crosses, 2

Paint Horses, 1 Canadian and 1 Thoroughbred.
The horses were housed indoors and fed dry hay. Once they experienced an exacerbation, the horses were fed alfalfa pellets and steamed hay for 4 weeks. Every week, the researchers checked the clinical health and lung function and recorded the findings. They also took bronchoalveolar lavage (BAL) fluid for cytology and recorded mucus scores before and after each diet was implemented.

They found that the clinical scores improved significantly over the course of the diet (P< 0.001, no diet effect or time-diet interactions), but the pellets caused a higher decrease in weighted clinical scores.

The pellet diets decreased weighted clinical scores from a median of 13 (5.5 quartile range) to 2 (1.5). On the steamed hay diet, weighted clinical scores 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),” the researchers wrote. “With steamed hay, the 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).”

They also found that neutrophils in the BAL samples also decreased, regardless of the diets (pellets: 40.2% [24.4] to 20.1% [11.0]; steamed hay 30.9% [20.2] to 25.7% [17.6]). MeV

For more information:
Symoens A, Westerfeld R, Mozo Vives B, et al. Asthma Steamed hay and alfalfa pellets for the management of severe equine asthma. Equine Vet J. epublished 2024 Aug 20.
https://beva.onlinelibrary.wiley.com/doi/10.1111/evj.14209