Surgical excision of melanomas in the anal region and reconstruction of the anus in 11 horses

Summary This case report describes the surgical excision of large perianal and perineal melanomas, and reconstruction of the anus in 11 grey horses. Four horses had a history of painful defaecation or urination due to extensive tumours. Seven horses had no clinical signs at the time of admission but had rapidly growing nodules around the anus with infiltration of the surrounding musculature. All horses had melanomas in remote parts of the body. The surgical procedure involving removal of the external anal sphincter followed by reconstruction of the anus, and the pre‐ and postoperative surgical considerations for performing the operations in standing horses were described. In six cases, reconstruction of the vulva and perineal region was also performed, and large perirectal melanomas were removed in five cases. All horses had a good outcome characterised by resolution of clinical signs, marked improvement in quality of life and a high owner satisfaction level. Our results show that, while early intervention is crucial in treating equine melanoma, a good outcome can be achieved even in seemingly hopeless situations.