Gastric ulcers affect up to 90% of performance horses and many leisure horses; management practices including feeding frequency and turnout access significantly affect ulcer prevalence and severity.
Gastric ulcers cause persistent pain that affects behaviour, appetite, and performance — horses may present with vague performance decline, reluctance to work, or changes in temperament rather than obvious pain signs. The primary cause is management mismatch with the horse's evolved digestive physiology: horses evolved for continuous forage consumption, not twice-daily concentrate meals with long gaps. Management that provides continuous forage access and maximises turnout time prevents most ulcer development without pharmaceutical intervention.