RESUMEN
A 9-year-old male Malinois was presented for further workup of acute melena, hematemesis and chronic weight loss for a duration of one month. Clinically, the patient presented with a mildly reduced general condition. Blood tests revealed mild non-regenerative anemia as well as a mild elevation of alanine aminotransferase (ALT). Ultrasonography showed signs of an early mucocele. Treatment with gastroprotectants failed to lead to clinical improvement and the dog developed progressive anemia. Gastroduodenoscopy was unremarkable. Due to persistent clinical signs, exploratory laparotomy was performed. An ulcerated bleeding mass was detected at the gallbladder neck. Histopathological examination led to the diagnosis of a neuroendocrine carcinoma. There was no evidence of a mucocele on histopathology. Melena and hematemesis subsided postoperatively and 13 months after cholecystectomy, the dog remains without clinical signs. Neuroendocrine carcinomas of the gallbladder should be considered as a rare cause of melena and hematemesis in dogs.