Cobblestone-like Gastric Mucosal Changes on Endoscopy in Dogs with a History of Prolonged Proton Pump Inhibitor Therapy.

This study describes the clinicopathological features of seven canine cases showing a diffuse cobblestone-like gastric mucosal pattern on endoscopy. Cases were retrospectively retrieved from endoscopic databases (2017-2025). Clinical data, treatment history, endoscopic findings, and histology were reviewed. Endoscopically, all dogs exhibited thickened, irregular, and poorly distensible gastric folds. Histopathologic examination showed mild-to-moderate foveolar hyperplasia, variable cystic dilation of the fundic glands, mild chronic lymphoplasmacytic inflammation, and interstitial fibrosis. Parietal-cell population was variably increased and predominant (hyperplasia). Because these features can overlap widely among reactive and hyperplastic gastropathies, interpretation required correlation with clinical and endoscopic findings in addition to histopathology. All dogs had a history of prolonged omeprazole administration, and most showed clinical improvement after dose reduction or treatment withdrawal. Follow-up endoscopy in two dogs documented divergent outcomes, with marked improvement in one dog and only minimal changes in the other. These findings suggest that this cobblestone-like pattern represents a benign, reactive, and potentially regressive gastropathy, possibly associated with chronic acid suppression. Recognition of this appearance may assist clinicians in differentiating reactive gastropathy from proliferative or neoplastic conditions and supports prudent use of long-term proton pump inhibitors in dogs with chronic gastrointestinal disease.