Large duodenal hyperplastic polyp causing haematemesis and melena in a dog.

A 5‐year‐8‐month‐old, female, neutered Cavalier King Charles Spaniel presented with a 7‐day history of melena, intermittent haematemesis, mild lethargy and normal appetite. Following hospitalisation and supportive treatment with intravenous fluid therapy and medications, the clinical signs improved. On abdominal ultrasound, a proximal duodenal mass was seen. Gastrointestinal endoscopy identified an intraluminal duodenal mass lesion and endoscopic biopsies were obtained. Cytology from ultrasound‐guided fine‐needle aspirates and histology from endoscopic biopsies were suggestive of an epithelial duodenal polyp. Surgical resection via duodenotomy was performed, and the dog was discharged the following day with complete resolution of the clinical signs. The histological diagnosis was compatible with a hyperplastic polyp, not previously reported in this location. Little is known in terms of clinical signs, diagnostic options and prognosis following resection. In a follow‐up consult and abdominal ultrasound 351 days later, there was no polyp regrowth or recurrence of clinical signs. [ABSTRACT FROM AUTHOR]