Prolonged exposure of the stomach to gastric acid can cause damage to the stomach lining, resulting in a painful condition for the horse.Research has shown that as many as 90% of horses in training have some level of stomach damage.Gastrointestinal upsets are common amongst many horses. Symptoms may include:Gastric sensitivityLoose manureWindsuckingLoss of appetiteWeight lossStable vicesPoor coat conditionUnsettled behaviour..