Tumors of the female urogenital tract can involve the external genital area or internal structures. Melanoma involving the vaginal labia is the most common tumor. It often presents as an extension of tumor tissue from adjacent structures but can alsobe a primary site on the labia. Melanomas have been reported, in a retrospective study, to represent 3.8% of all neoplasms seen in the horse, and they represent 15% of all skin tumors of the horse.1 When present, there is almost always additional melanosis in the perianal tissue or on the ventral tail. This is seen predominantly in grey horses and 80% will go on to develop them. Melanomas can be diagnosed without histology and approximately one third will become malignant later in life.2,3 Melanoma canbecome unsightly, infected, or interfere with breeding and/or parturition. Conventional surgical resection using heavy sedation, local anesthesia or epidural anesthesia is a very acceptable means of treatment. The CO_2 laser has also been used to assistwith resection and control hemorrhage. Wounds are frequently left to heal by second intention. Alternative treatments include medical or immunologic therapy (Oncept, ImmuneFX, Uni.Fla. vaccine) or growth/size suppression by oral administration of Cimetidine.
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