Malignant melanoma involving the aorta in a dog.

A four year old female Siberian husky presented with shifting hind limb lameness was euthanized and found to have disseminated malignant melanoma without oral, cutaneous or ocular involvement. The largest and possibly primary mass involved the aorta and sublumbar muscles and occluded as well as penetrated the aorta. Numerous smaller tumors were present in skeletal and soft tissues of both hind limbs, suggesting hematogenous spread from the aortic lesion.