A Canadian study shows that soaking hay can help control equine asthma. But, the researchers say, to achieve the best results an exacting protocol must be followed.

For the study, University of Montreal researchers selected 10 horses with severe asthma, commonly called heaves. An inflammatory condition characterized by labored breathing, coughing and increased mucus production, equine asthma is exacerbated by dust. Hay and bedding are primary sources of airborne particles in horse barns.

To prevent dust particles from becoming airborne, soaking hay prior to feeding has long been recommended for horses with asthma. However, the efficacy of this approach in reducing respiratory inflammation and improving lung function in horses had not been previously studied.

The study

At the beginning of the Canadian experiment, the horses were housed indoors and fed dry or dusty hay for six weeks to trigger their asthma. The researchers documented the severity of each horse’s respiratory disease. They observed clinical signs, assessed lung function and measured airway inflammation.

Next, the horses were divided into two groups. Five were fed alfalfa pellets instead of hay. Five others received hay that had been fully submerged in cold water for 45 minutes prior to feeding. The water was discarded after each soaking. In addition, any hay that dried out before being eaten was removed from the horse’s stall. This feeding protocol was continued for another six weeks, with the researchers measuring each horse’s lung function, indicators of lung inflammation (pulmonary neutrophilia) and mucus production at weeks two, four and six.

The results

The data showed that horses receiving soaked hay had fewer clinical signs, improved lung function, and reduced tracheal mucus production. Similar benefits were observed in those fed pellets, along with improved pulmonary neutrophilia.

The researchers conclude that “soaked hay can control airway obstruction in horses with severe asthma.”

They note that owners who do not see an improvement may not be soaking it long enough. But, they say, “The strict protocol for soaking and discarding dried-out hay in this study could be considered too great of an inconvenience by owners.”

Reference: “Effects of soaked hay on lung function and airway inflammation in horses with severe asthma,” Journal of Veterinary Internal Medicine, November 2023

To read about how to handle a heaves flare up, click here.