Many domestic horses, donkeys, and mules develop painful stomach conditions such as equine gastric ulcer syndrome (EGUS). Although gastric ulcers are common in sport and leisure horses, confirming a diagnosis requires gastroscopy—and not every veterinarian has immediate access to the equipment—so treatment might be delayed.

Researchers on new study suggest horse owners and caretakers could be able to reliably recognize specific behavioral patterns—called signature behaviors—in horses with gastric disease. Early recognition and prompt care could lead to improved welfare and performance.

Studying Common Signs of Equine Gastric Ulcers

“In our study, we retrospectively evaluated our clinical records to blindly evaluate whether our long-held impression that a certain cluster of behaviors was associated with gastric disease,” said Sue McDonnell, PhD, Certified AAB, founding head of the equine behavior program at the University of Pennsylvania’s School of Veterinary Medicine, in Kennett Square.

Researchers at the school’s Havemeyer Equine Behavior Laboratory reviewed clinical reports of 30 horses, each of which underwent a 24-hour hospital video evaluation and gastroscopy to assess gastric health.

Of those horses, 24 showed behaviors typically linked to gastric discomfort such as frequent deep abdominal stretches (nuzzling, swatting, nipping, and gazing focused on the abdomen just behind the elbow). Veterinarians later diagnosed all 24 horses with gastric disease, including ulcers or impaction.

The six remaining horses showed no signature behaviors. Four had no signs of gastric disease on gastroscopic examination, and two had only mild gastric lesions. These results support the idea that these specific behaviors serve as reliable indicators of gastric discomfort.

Owner Interpretation of Equine Gastric Ulcer Behaviors

Still, horse owners or others who work around equids often misinterpret behaviors associated with gastric discomfort. “When equestrians notice these behaviors, they mostly just don’t realize the association with gastric discomfort, and there is a lot of misinformation offering alternate explanations for some of these behaviors,” McDonnell said.

This misunderstanding poses a significant welfare concern. Horses rarely show discomfort with people present, she added. Recognizing these signature behaviors can help owners and caretakers identify horses in need of further evaluation. She also noted the potential for artificial-intelligence-assisted technologies to help detect pain-related behaviors in horses—an advancement that could improve early detection and support better welfare outcomes. Currently, gastroscopy remains the gold standard for diagnosing gastric ulcers accurately and guiding treatment.

“Sadly, horses with gastric discomfort often develop problematic avoidance behaviors,” said McDonnell. “These attitude changes and undesired behaviors, as well as poor performance, are typically first misattributed to misbehavior or all sorts of other explanations, and all too often punished, which is detrimental to horse welfare.” She emphasized the importance of first ruling out pain or discomfort when a horse begins to act out.

Take-Home Message

Recognizing common signs of gastric discomfort in horses is crucial to improving horse health and welfare. “Hopefully, more people will learn to recognize gastric and other pain-associated behaviors and subsequently get a veterinary diagnosis so that appropriate treatment can be started as soon as possible without unnecessary and prolonged suffering,” McDonnell said.The study, “Behavioral Signature of Equine Gastric Discomfort? Preliminary Retrospective Clinical Observations,” appeared in Animals in January 2025.