A sustained increase in gastric pH is central to the successful treatment of upper gastrointestinal (GI) erosion/ulceration and esophagitis in cats. Thus, acid suppressant drugs, such as proton pump inhibitors (PPI; e.g. omeprazole) and histamine-2 receptor antagonists (e.g. famotidine), are commonly prescribed. Famotidine is a weak acid suppressant and leads to a diminished effect with repeated administration. For this reason, famotidine administration is not advised. Omeprazole, which must be administered twice-daily, is more effective than famotidine but still does not reach pH goals for treatment of GI ulcerative disease even when administered twice-daily. Moreover, omeprazole must be given on an empty stomach 30 minutes prior to the main meal. The requirement for twice-daily administration and the need to administer omeprazole without food in cats likely leads to disruption of the human-animal bond, poor owner adherence, and treatment failure. Thus, veterinarians are increasingly prescribing newer PPIs that are longer acting and can be given with food. The efficacy of these novel gastroprotectants have not been evaluated. Although we believe that some of these drugs will be more effective than omeprazole, we have concerns that some will be no better than placebo in cats. This study would be the first to investigate the efficacy of these novel gastroprotectants in cats. In a randomized, crossover study, cats will receive lansoprazole, dexlansoprazole, or esomeprazole orally twice-daily for 4 days. Intragastric pH will be compared among treatments. The study objective is to evaluate the efficacy of these specific drugs and, ultimately, improve treatment outcomes.