By Maia Aitken, DVM, Large Animal Surgery Intern, New Bolton Center, University of Pennsylvania School of Veterinary Medicine
[November 15, 2010; Kennett Square, PA]--As the days get shorter and fall comes to an end, many horse owners have already begun getting their horses ready for the winter season. Here in the mid-Atlantic region, this typically revolves around ensuring that horses are warm and appropriately blanketed for the impending cold. However, even in climates where temperatures remain mild throughout the winter, horses suffer from ailments similar to those that plague their owners, from runny noses to chapped skin, even cabin fever! At New Bolton Center, where we see patients referred from throughout the region, respiratory difficulties stand out as being significantly associated with the cold season.
With so much emphasis on keeping our horses warm, it is often our first instinct to lock windows and cover vents. We easily forget that no matter what the season, good air quality is essential to the health of our stabled horses. By disconnecting fans and closing barn doors, we may actually exacerbate existing respiratory conditions or even predispose our horses to developing respiratory problems. By the time ammonia levels become detectable to the human nose, the buildup in the barn is already sufficient to damage a horse’s respiratory tract. Dust and mold can also initiate or aggravate allergies, most notably “Heaves.”
“Heaves” is the common term for recurrent airway obstruction (RAO), a respiratory disease characterized by inflammation and narrowing of the small airways within the lungs. Common clinical signs include coughing, mucoid nasal discharge, and increased respiratory rate and effort. In severe cases, the nostrils may flare, wheezing may be heard, and the effort associated with respiration, especially expiration, is so great that the abdominal muscles become prominent, resulting in a characteristic “heave line.” Although the exact cause of RAO is unknown, the disease is exacerbated by the inhalation of airborne dusts, including those associated with hay and bedding materials.
General recommendations for managing a horse with RAO include maintaining the horse on pasture for 100% of the time. However, during the winter months, when this may be impractical, managing the barn environment to reduce dust becomes essential. The first step is to improve ventilation. This will not only help a horse with RAO, but will be beneficial in reducing the risk of other respiratory diseases. Passive ventilation involving floor and soffit level vents provides a draft-free flow of fresh air. Mechanical ventilation systems also provide fresh air without causing drafts. However, simply opening stable doors and windows or keeping fans above ground and running will improve ventilation. It is much healthier for stabled horses to have access to cool fresh air than stagnant air within a sealed building.
In addition to improving ventilation, a number of other management practices may be employed to reduce the amount of inhaled particles. Such changes include moving horses outside while mucking, cleaning or throwing hay; thoroughly soaking hay or feeding dengi; and using water or dust suppressants in riding arenas. It is impossible to eliminate all dust from the environment, but you can make a difference in controlling RAO by focusing on what triggers your horse’s signs and implementing the strategies that make sense in your situation.