Question: My 16-year-old gelding developed heaves after I moved him to a new barn. I've stopped riding him in the indoor arena and have seen some improvement, but I'm wondering if there is anything else I can try. He is kept in the stall half the day and turned out the other half---either during daylight hours or overnight, depending on the season. The bedding is a thin layer of shavings over mats and the hay is a timothy mix that smells fresh.
Name withheld by request
Answer: "Heaves" is the common term for recurrent airway obstruction (RAO), a respiratory disease characterized by the narrowing of the small airways within the lungs. Signs include coughing, mucus discharge from the nose, and fast, deep breathing. In advanced cases, the abdomen lifts with each breath, the nostrils flare and the horse makes a wheezing sound.
Although the exact causes of RAO are unknown, the disease is aggravated when a horse is exposed to airborne dusts typically found inside stables.
When their exposure to these dusts is limited, however, most horses with heaves can remain free of signs. The general recommendation is to keep these horses on grass pasture 100 percent of the time. When they must be stabled, it is extremely important to manage their environment to reduce or eliminate their exposure to dust.
What you've done so far is good. Although this is far from a complete list, you might consider a few more tactics for managing a horse with heaves:
Keep a daily journal. By recording details such as weather conditions, turnout schedules and stable events such as new shipments of hay, you may be able to pinpoint conditions that trigger your horse's heaves.
Improve ventilation. Keep stable doors and windows open as much as possible. If your horse's stall does not have an open window, consider moving him to one that is as close as possible to a large doorway. If you use fans to improve ventilation, place them up and off the floor so they do not blow dust from the ground into the stalls/aisles.
Move horses outside when mucking and cleaning. Stall cleaning, raking/sweeping of aisles, de-cobwebbing, throwing hay/straw down from lofts, leaving tractors or 4-wheelers running in the aisles and similar activities generate very high concentrations of particulates. Even after the initial "clouds" of dust disappear, very small particles, those that reach deep into the lung, stay suspended for quite a while. If you must do these types of chores while the horses are inside, consider using water to help control dust levels.
Replace hay with a "complete feed" that includes roughage. If this isn't practical and you must feed hay, soak it thoroughly--so that the water drains through it--prior to putting it in the stall. Also, divide the hay into multiple smaller feedings over the course of the day. This may reduce the horse's tendency to "dive in," grab and shake the hay, which produces high concentrations of dust around the nostrils. Placing the hay either on the floor or as low as possible helps mucus to drain from the air passages. And, of course, do not throw hay up and over stall walls.
Use water or commercial dust suppressants in riding arenas. With a garden hose and rotary sprinkler to wet the surface, you can greatly reduce dust in indoor and outdoor arenas. Commercial dust suppressants remain effective longer than water and may be more practical during the winter months.
It is virtually impossible to completely eliminate dust from your horse's environment, but you can make a big difference in controlling heaves just by focusing in on what triggers his signs and then implementing just a few environmental control strategies that make sense in your situation.
Melissa Millerick-May, MS, PhD
Michigan State University
East Lansing, Michigan