Melanoma

Melanoma occurs commonly in dogs with pigmented (dark) skin. Melanomas arise from pigment producing cells called melanocytes, which are responsible for coloring the skin. Any dog can be affected, but Gordon Setters, Standard and Miniature Schnauzers, Doberman Pinschers, and Scottish terriers, among others, are at increased risk to develop melanoma, suggesting that this disease may have a hereditary component. Melanomas can occur in areas of haired skin, where they usually form small, dark (brown to black) lumps, but can also appear as large, flat, wrinkled masses. Melanoma of the haired skin in dogs is usually a benign tumor, although it can cause severe discomfort. In contrast, malignant melanoma, which develops in the mouth or in the distal limbs (usually the toenail beds), is an incurable disease. These tumors have very often spread to distant parts of the body (metastasized) by the time they are first noticed, making complete surgical removal impossible.

Radiation therapy can help extend the lives of affected dogs, but also is ineffective against tumor cells that have metastasized. Chemotherapy is also not considered capable of adequately controlling canine malignant melanoma.

Melanoma seems to be uniquely responsive to immune-based therapies, and various novel approaches are under development to treat this disease.