Your horse’s heaves have been under control for months. By paying careful attention to his environment you’ve kept him breathing freely, even without medication. But a single dusty flake of hay, missed during the rush of evening feeding, was enough to trigger a flare-up. A few coughs at the beginning of your ride were the first clue and now, hours later, you’ve found your horse standing in his pasture, working so hard to exhale that you can see his abdominal muscles bulge.
Technically known as recurrent airway obstruction (RAO), a type of equine asthma syndrome, heaves is an inflammatory reaction to inhaled dusts, molds or other allergens in the horse’s environment. Exposure causes the airways to swell, constrict and clog with excess mucus, making exhalation more difficult. RAO typically affects older horses, and while the disease cannot be cured, you can take steps to manage it and keep your horse’s airways healthy. Measures to reduce the dust in a horse’s environment---such as wetting or steaming the hay, using low-dust bedding and increasing turnout time---can help keep heaves under control. But sometimes even the best efforts cannot prevent a flare-up. When one occurs, it’s time to call the veterinarian. But as you wait, you’ll want to try to make your horse more comfortable.
WHAT TO DO WHILE YOU WAIT
• Keep the horse quiet and still. Any agitation or exertion can tax his already limited intake of oxygen. Letting him stand with a quiet buddy may help keep him calm. Avoid feeding hay or concentrates, however---the dusts they contain may aggravate his condition.
• Get him some fresh air. If the horse is in a stall or a dusty paddock, walk him out to an open grassy area or even a parking lot---away from the allergens that may be provoking the condition. Some horses develop a related condition, called summer pasture-associated heaves, caused by exposure to pollens and other allergens in open fields. If that’s the case, move the horse into a clean, well-ventilated stall. An air-conditioned space---if you have one available that can safely accommodate your horse---is an even better option. Cooler, less humid air is easier to breathe, and the filters in the unit remove dusts, pollens and other particles.
• Monitor his vital signs. Count the number of times per minute your horse breathes in and out---then check again every five minutes or so. If his breathing rate increases drastically, his condition could be getting worse, and you’ll want to call your veterinarian with an update. Also keep tabs on the color of your horse’s gums, and alert your veterinarian if they’re extremely pale or bluish in color; this is a sign of oxygen deprivation. Temperature and heart rate can also be useful information for your veterinarian.
WHAT NOT TO DO
Do not administer medications without specific instructions from your veterinarian. Sedatives and tranquilizers, for example, may make the problem worse.
IN BRIEF: HEAVES
Definition: “Heaves” is the common term for recurrent airway obstruction (RAO), a respiratory disease characterized by a narrowing of the small airways of the lungs, which makes exhaling difficult.
Causes: Tiny dust particles pulled deep into the airway trigger inflammation in the lungs. Research suggests that some horses inherit an increased sensitivity to dust, which makes them more susceptible to RAO.
Signs: fast, deep breathing along with coughing and mucus discharge from the nose. In advanced cases, a horse’s nostrils flare and an audible “wheeze” may be heard with each breath. Horses with chronic RAO can develop a distinct “heaves line” along the abdomen as the muscles that help them exhale get overused.
Treatment: Steroids and bronchodilators given orally or inhaled can be used in “rescue” situations, but long-term treatment of a horse with heaves requires eliminating as much dust as possible from his environment. This often requires that the horse be kept outdoors on grass pasture and fed hay that has been thoroughly watered down to reduce dust. Horses with heaves may also benefit from a dust-free pelleted ration.
This article first appeared in EQUUS issue #472, January 2017.