More Than Just Attitude: Uncovering the Hidden Cause Behind a Horse’s Sudden Resistance- Pyloric Ulcers

When Performance Falters: Why Behavioral Changes Can Signal Serious Gastric Issues

From the outside, this horse looked like many high-level athletes: full of fire, a little opinionated, but always manageable under saddle. Described by its owner as “always having a bit of hotness about it,” the horse was in a structured training program and actively competing on the show circuit.

At a past show, however, things began to shift. By the end of the week, the horse became increasingly difficult to ride. It no longer moved off the leg but instead “sucked back,” resisting forward momentum. Initially, the behavior was chalked up to fatigue—after all, even the best need a break. The decision was made to scratch the horse from its final classes, allowing it time to rest and recover at home. 

Despite the time off, the behavior didn’t resolve—it progressed.

Back in its regular program, the horse continued to show resistance. That subtle hesitation evolved into flat-out refusal. While it would eventually carry on and complete its rides, something clearly wasn’t right. During that week back, when asked to work, the horse reared—a behavior it had never shown before. Notably, its work tracking left became immediately problematic after the show. When the left leg was applied, the horse would pin its ears, try to turn and bite, or even rear to avoid the pressure.

This marked a significant behavioral change—not just a “hot horse” having a bad day, but a horse trying to communicate discomfort. It was no longer just resistance or attitude; it was pain presenting through performance issues.

The owners immediately informed me something was off, and I suggested we come to their farm and gastroscope the horse.

What made this case especially confusing for the owners was that the horse showed no outward signs of discomfort. It wasn’t girthy during tacking up. It hadn’t dropped weight. Its coat was shiny, its appetite normal, and its general health appeared excellent. There was no indication, on the surface, that anything was wrong. However, I explained that the behavioral change—particularly the reactivity to the leg, refusal to go forward, and the new tendency to rear—was a red flag. These kinds of changes can often be a horse’s way of expressing internal discomfort, which is why I strongly recommended we gastroscope the horse.

I recommended the horse be pulled from all training and work pending evaluation.

The horse was fasted over-night and I performed a gastroscopy the following morning.  Gastroscopy revealed moderate to significant ulceration of the pylorus (see images). The glandular stomach and non-glandular stomach were normal. Pyloric Ulcers are a significant finding and requires specific medication. A combination of Gastrogard (omeprazole), sucralfate, and misoprostol are typically indicated in such cases. Equally important is follow-up gastroscopies at 45-day intervals to monitor the healing process.

We are happy to report that this horse is now back to showing and winning in the ring. Working closely with the owner and trainer, we developed a maintenance program that includes a dose of Gastrogard (omeprazole) prior to and during show weeks, sucralfate administration, and consistently providing soaked alfalfa pellets before every ride. This careful management has helped keep the horse comfortable, healthy, and performing at its best.

 Ulceration of the Pylorus Exhibit A

 Ulceration of the Pylorus Exhibit B

 Ulceration of the Pylorus Exhibit C

 Ulceration of the Pylorus Exhibit D