Surgical removal of a perirectal melanoma through sphincterotomy and rectal wall resection in a horse

Case Report Melanomas are among the most frequent neoplasms in grey horses. Deep perirectal melanomas, however, are uncommon and challenging to excise due to their proximity to the peritoneal reflection. This report describes the successful standing removal of a large (16 × 8 × 6 cm) perirectal melanoma firmly adherent to the dorsal rectal wall in a 19‐year‐old Lusitano gelding. Surgical access was achieved via a full‐thickness anal sphincterotomy at the 12 o'clock position, followed by en bloc resection of the tumour and adherent rectal wall using a vessel‐sealing device and a Gigli‐like suture snare. Postoperative management included intensive analgesia, laxatives and repeated manual evacuation until spontaneous defecation resumed. Despite transient impaction and complete wound dehiscence, healing progressed without major complications. At 3‐year follow‐up, the horse exhibited mild and only occasional faecal incontinence, no tumour recurrence and absence of colic episodes. This case demonstrates that complete standing resection of large, adherent perirectal melanomas is feasible and can result in excellent long‐term outcomes when combined with diligent postoperative care and gradual dietary adaptation.