Nonsteroidal anti-inflammatory drugs are widely used for treatment of animals. Their use is limited by frequent side effects commonly involving the gastrointestinal tract, most important of which is development of ulcerating lesions principally In the stomach. Unfortunately, presence of such lesions is often unsuspected because clinical signs may be overlooked until a complication develops. A 5-year-old, female mongrel dog was referred to Veterinary Teaching Hospital in Chungbuk National University. She was showed vomiting, anorexia and lethargy after administration of ibuprofen (400 mg/body, qid, oral) for 5 days. General examination and plain radiography were performed in the patient. Physical examination, hematologic values, chemical profiles, urinalysis and radiographs were normal. Therefore, endoscopic examination was performed in this patient and confirmed to show the gastric ulcer in pyloric region of the stomach. Drug therapy was performed successfully in this case. This article reports the development of a gastric ulcer associated with orthopedic disease treated by ibuprofen.