Jeff , Iowa, USA
When one of our horses developed respiratory problems, our veterinarian suggested we wash the hay before feeding to remove the dust as a way to reduce the occurrence of her flare-ups. We noticed a decrease in her coughing when we did that, but not completely. We used a garden hose to do the washing, which is often difficult in mid-winter Iowa.
Looking for a better way, we ordered the professional steamer model from Happy Horse. We have been using it twice a day, every day, for about 1 year now. Our horse's coughing has all but disappeared and the respiratory flare-ups greatly reduced in intensity and frequency. We had just one minor occurrence this past year, which we attribute to air-borne dust.
I can't imagine feeding our two horses hay that hasn't been steamed now.