Case description: A 2 yr old intact male donkey (Equus asinus) was presented to Hospital of Veterinary Medicine, Mansoura University with subcutaneous masses under the tail.
Clinical findings: Physical examination revealed the presence of 2 separate 5 × 10 and 5 × 8 cm diameter, round and firm subcutaneous masses.
Treatment and outcomes: Surgical removal of the masses applied under epidural anesthesia was performed. The masses were firm and pigmented. Multiple biopsies of the masses were collected and fixed in 10% neutral buffered formalin. Histopathologic evaluation of the biopsies revealed malignant dermal melanoma involving deep dermis, muscles, adipose tissue, lymph node and blood vessels. Multifocal areas of necrosis and dystrophic calcification were recognized. Hematologic and plasma biochemical parameters were within normal reference ranges. Two months post- surgery, hematologic and plasma biochemical parameters remained within normal limits. The animal did not show any clinical signs of disease or evidence of recurrence until five months follow-up post-surgery. To the author’s knowledge, this is the first report of successful surgical excision of a malignant dermal melanoma in a donkey.