Equine Asthma – The Horse


“Most importantly, do not feed hay,” says Lavoie.

Instead, use a cubed or pelleted diet. If you do provide hay, soak it before feeding it to your horse. Hay soaking involves completely submerging the ration for 30 minutes, not just watering it down with a hose.

“Other hay alternatives include oiled hay such as the Nutri-Foin system, haylage, and pasteurized hay,” Lavoie says.

Steaming hay can be performed in place of soaking hay. Couëtil says molds will persist if the hay is not fully steamed to the inside of the bale. Further, the steamers need to be cleaned properly to ensure no molds get left behind. Commercial steamers take about 1 hour per bale, and some owners might find the cost prohibitive.

“Haylage, a well-known feedstuff widely used in Europe, can maintain SEA horses in remission while in the barn,” says Couëtil. “One drawback is that haylage is associated with the risk of botulism, but this is not typically a concern for properly harvested and stored haylage. Also, vaccination helps protect horses against botulism.”

While the above-mentioned feeding recommendations are clear and widely advocated for by veterinarians around the globe, putting them into practice has proven to be challenging for many horse owners.

In the study by Simões et al. involving 39 client-owned horses, researchers saw good compliance to allergy avoidance strategies in only six cases. This means about 85% of owners were unable to adopt many of the outlined management recommendations. Not surprisingly, many horses in the study did not show substantial improvements in clinical signs of their disease. In addition, many horses required medications to help control their asthma during the one-year study period.

The easiest management changes to adopt appeared to involve those that did not mandate a change in the owner’s behavior or time budget. They happily bought new bedding to replace straw but were less eager to turn horses out or soak hay.

In a 2018 study Mathilde Leclere, DVM, PhD, Dipl. ACVIM, and colleagues from the University of Montreal’s Faculty of Veterinary Medicine found more positive results but still saw room for improvement. Specifically, Leclere wrote, “adherence was surprisingly high, as was overall satisfaction. All owners indicated that they had implemented at least one of the recommendations to decrease exposure to hay dust or barn dust.”

More than half of the 33 owners reported hay soaking rather than feeding dry hay, and another 12 owners completely replaced hay with a pelleted diet. Further, 26 reported turning their horses out more frequently than before the asthma diagnosis.

Leclere said reasons owners might not be able to follow recommended management strategies include an incomplete understanding of why they’re important or a conscious decision that the “burden of the treatment outweighs the burden of the disease.”

In the long run, though, it appears owners can suffer “asthma fatigue” and revert back to their old habits. For Leclere’s 33 owners, only 30% reported they had made a “rigorous and permanent change in management” after their horses were diagnosed with asthma. Indeed, 44% of owners began offering dry hay again, and 26% of owners reported turning their horses out less over time than they originally did at the time of diagnosis.


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