Definition of Melanoma
Melanoma, sometimes called “skin cancer,” is a common, locally invasive and frequently malignant type of cancer that can affect dogs, especially older ones. The different forms of melanoma are classified by location: skin (cutaneous melanoma), eyelids (ocular melanoma), nail bed (subungual melanoma) and oral cavity (oral melanoma). What causes melanoma isn’t well-understood. We do know that melanomas arise from uncontrolled growth of cells that produce melanin, a dark pigment that is found in hair, skin, eyes and certain nerves. Unlike in people, melanoma in dogs doesn’t seem to be accelerated by sun exposure. In fact, dark brown and black dogs get melanoma more often than lighter animals. The fact that certain breeds get melanoma more commonly than others suggests that the disease has a genetic component. Most affected dogs show no signs of illness, unless and until the disease has spread to vital organs.