For the second year, a nationwide series of more than 160 gastroscopy events showed 60 percent of horses were identified with stomach ulcers.

"This is the second year that these scopings were able to show horse owners the type of potentially painful stomach ulcers that their horses have been dealing with," says April Knudson, DVM, manager, Merial Veterinary Services. "Many times, horses are suffering in silence from stomach ulcers due to their natural tendencies as a prey animal to mask pain. In talking to many of these owners myself, they are frequently surprised to find out their horse had been suffering from stomach ulcers, but the evidence is clear."

At these events, veterinarians evaluated the horses' stomachs using gastroscopy, which is the only definitive way to determine if a horse has ulcers, Dr. Knudson says.

Throughout the year, 1,532 horses across the country participated in events. Overall, 922 horses from 37 states had some ulceration as identified by gastroscopy. Horses of varying ages and disciplines were found to have all grades of stomach ulcers, including:

    * Horses from 2 months to 30 years of age

    * 610 horses, or 40 percent, were Grade 0 (healthy, nonulcerated stomach)

    * 471 horses, or 31 percent, were Grade 1 (mild ulcers, with small lesions or damaged tissue)

    * 319, or 21 percent, were Grade 2 (moderate ulcers with large lesions)

    * 132, or 9 percent, were Grade 3 (extensive lesions with deep ulceration and bleeding)

    * 86 percent of racing horses had some grade of ulcers (226 total participating)

    * 59 percent of eventing horses (113 total participating)

    * 59 percent of hunter jumpers (168 total participating)

    * 52 percent of barrel racing horses (122 total participating)

    * 48 percent of dressage (107 total participating)

There are many triggers for stomach ulcer development, and stress is an important factor, Dr. Knudson says.

Horses are especially sensitive and may experience stress when exposed to situations you would think of as normal, including competition, training, travel, lay-up due to sickness or injury, shows or events, limited turnout or grazing, or trailering.

Ulcers can develop quickly, too. One study showed that horses can develop stomach ulcers in as little as five days.