A case of the heaves: Veterinarians deal with recurrent airway obstruction in horses
Overall solution—limit exposure
As noted, the main concern for horses with heaves is to limit their exposure to organic dust. "If horses are confined to stables, turn them outside as much as possible. Put the horses completely off hay, and feed them pellets or cubes," says Léguillette. Léguillette also recommends the use of hay steamers. The steam kills molds and bacteria and washes the hay to decrease dust and organic particles. "They seem to work very well. I strongly recommend preventing exposure to organic dust as much as possible. I also recommend that people turn their horses out when they sweep the barn area or when bedding the stall to reduce exposure to dust, and to wet the barn area when they sweep to keep the dust down. If people are turning their horses out, even for only a few hours per day, it should be at the time they're cleaning the stall and barn areas. Wait a couple of hours before bringing the horse back into the barn."
In Calgary, researchers even found that horses that had been turned outside during cold weather did better than those left in confinement with dust. "The barn is a bad place for accumulation of dust, especially for horses with lung disease," Léguillette says.The main implication of this research interest—changes occurring in the lungs of horses with heaves are quite severe, says Lavoie. "It's probable that once these horses are heave-affected, once the disease has progressed, it might be too late to reverse the condition. One probably needs to intervene much earlier.
"What we don't know at this point for those horses with mild asthma or inflammatory airway disease: Do those animals go on to develop more severe disease? We need to recognize early on horses that will eventually develop heaves and apply appropriate therapy or change their environment to change this progression, which eventually causes this severe decline in airway function."
1. Lavoie JP. Heaves in horses: Allergy or non-specific response to environmental antigens, in Proceedings. 11th Geneva Congress on Equine Medicine and Surgery. 2009;23-26.
2. Leclere M, Lavoie-Lamoureux A, Lavoie JP. Heaves, an asthma-like disease of horses. Respirology 2001;16(7):1027-1046.
3. Leclere M, Lavoie-Lamoureux A, Gélinas-Lymburner E, et al. Effect of antigenic exposure on airway smooth muscle remodeling in an equine model of chronic asthma. Am J Cell Mol Biol 2001;45(1):181-187.
4. Wasko AJ, Barkema HW, Nicol J, et al. Evaluation of a risk-screening questionnaire to detect equine lung inflammation: results of a large field study. Eq Vet J 2001;43(2):145-152.
Ed Kane, PhD, is a researcher and consultant in animal nutrition. He is an author and editor on nutrition, physiology and veterinary medicine with a background in horses, pets and livestock. Kane is based in Seattle.