Malignant melanoma in a Dutch Lop rabbit

Abstract

Malignant melanoma was diagnosed via complete excisional biopsy of a 6mm pigmented nodule on the maxilla of a 7-year old intact male Dutch Lop rabbit. The mass was noted three weeks prior to presentation. Treatment with the canine melanoma vaccine began 1 month post-operatively following a standard canine protocol (1 vaccine q2 weeks for 8 weeks). Local recurrence was noted 6 weeks after excisional biopsy. This time advanced imaging (MRI,CT) indicated the mass had spread to local lymph nodes and was nonresectable. Palliative radiation therapy was added to the patient's treatment regimen, though the mass continued to grow. The patient died 20 weeks after initial presentation. Necropsy revealed extensive metastasis throughout the body. Although malignant melanomas have been described in rabbits, studies of neoplasia in lagomorphs are largely confined to spontaneous or induced states in laboratory animals. Despite aggressive treatment this case is consistent with previous descriptions of aggressive and metastatis melanomas in lagomorphs.