Gastric Ulcer Essay

Highly prevalent in the equine industry, gastric ulcers appear in sixty to ninety percent of horses depending on athletic demand, lifestyle, and age (Bell et al., 2007, Nadeau et al., 2003). While gastric ulcers primarily effect the un-protected, non-glandular region of the stomach, above the margo plicatus, they can appear in any area of the stomach (Nadeau et al., 2003; Videla and Andrews, 2009). An overall decrease in performance, weight loss, and colic are typical indications of gastric ulcer presence, although symptoms are often vague and may never manifest (Bell et al., 2007; Videla and Andrews, 2009). Gastric endoscopy is the only way to clinically diagnose gastric ulcers; however, veterinarians will also assess the horse’s history
and clinical signs (Bell et al., 2007; Videla and Andrews, 2009). Treatment is often an inhibitor of acid secretion, such as omeprazole, which increases the pH of the stomach, making it less susceptible to ulceration (Andrews et al., 1999). There is still much needed research concerning gastric ulcers; although, recent studies have highlighted the numerous roles nutrition has in the causation, treatment, and prevent/management in this field. Management of the average performance horse in today’s society provides an unnatural environment for the horse, with stall confinement, solitary housing, increased exercise, and large, infrequent meals consisting of concentrates.
All of these aspects are risk factors for gastric ulcers through both physiological and emotional stress (Videla and Andrews, 2009). Due to the prevalence of gastric ulcers in the horse, extensive research concerning which aspect of equine nutrition has the most impact on this condition has been conducted. Of the above listed predisposing factors, intermittent feeding patterns are a common theme. The horse has evolved to eat several small meals throughout the day and continuously secrete hydrochloric acid into the stomach (Bell et al., 2007; Berschneider et al., 1999). Mastication stimulates saliva production, which acts as an acid buffer in the equine stomach. Food withdrawal results in a decrease of gastric pH via lack of saliva entering the stomach. It is hypothesized reduced digesta volume causes an excess splashing of gastric juice on the non-glandular region of the stomach. Subsequently, there is an increased likelihood of acid reaching the non-glandular region of the stomach and ulcer formation (Bell et al., 2007). Similarly, exercise is shown to induce ulcers in both feed and fasted horses (Lorenzo-Figueras and Merritt,
2002).
In a study conducted by Lorenzo-Figueras and Merritt (2002) exercise resulted in a drastic drop in gastric pH and a decrease in volume of the non-glandular region of the stomach. Both physiological responses occurred in fasted and fed horses, with the change appearing at the trot and gallop. Authors believe the response appeared at the trot and gallop as horses do not elect to stay in these gaits for extended periods of time. Decreased stomach volume is a result of pressure exerted on the stomach, not the tightening of the stomach wall during exercise. Authors claim the decrease is gastric pH is related to the decrease in stomach volume, it is this decrease in pH that results in gastric ulcers and explains the frequent, severe ulcers found in racehorses (Lorenzo-Figueras and Merritt, 2002). Below is a graph representing the change in pH and stomach volume during exercise