Melanocytes are cells in the skin or gums that produce pigment or melanin. A melanocytic tumor of the skin or toes is a tumor that arises from melanin-producing cells in these locations. These tumors are also known as melanomas. They can be benign or malignant. Benign tumors can invade the local area around the tumor. Malignant melanoma can spread (metastasize) to bone, lymph nodes, lungs, and abdominal organs. The tumor can develop anywhere on the body. Most commonly, it occurs on face, trunk, feet and scrotum. The tumor can be pigmented or non-pigmented, depending on its location but this does not affect the prognosis.
Melanocytic tumors of the skin and digits are fairly common in dogs. Scottish terriers, Boston terriers, Airedale terriers, cocker spaniels, boxers, English springer spaniels, Irish setters, Irish terriers, chow chows, Chihuahuas, and Doberman pinschers are the more commonly affected breeds. The tumors may be more common in male dogs than in female dogs.
Symptoms in dogs of oral melanomas include increased salivation and saliva streaked with blood, bad mouth odor, and difficulty eating with weight loss. Oral melanomas can affect surrounding tissue and commonly spread to lymph nodes and lungs at the time of initial diagnosis. If a toe is involved the dog may limp.