Melanomas are tumors that arise from melanocytes (skin cells that are responsible for the pigmentation or coloration of the skin), skin cells of the basal skin layer. A common form of skin cancer in dogs, melanomas usually appear as small brownish black lumps just under the skin. Melanomas may also be seen in the mouth, toes and under the eyes, and are usually characterized by the dark-toned pigment. They are generally benign when they are seen in the skin, but in mouth, toe and eyes, they tend to be malignant and capable of metastasizing to other organs.
Skin tumors, both benign and malignant, are common in dogs. A tumor is actually a new mass of tissue that serves no purpose. However, cancerous tumors are capable of spreading to other parts of the body. Sometimes changes occur in the genetic structure (mutations) of the genes that control cell growth (the process of multiplication by division). This leads to the formation of tumors. These changes are very rare and silent, meaning that they do not interfere in the cell’s ability to function. But in certain cases, the tumor suppression genes are disabled or the oncogenes (genes that change normal cells to cancerous cells) are activated.
The risk factors for melanoma in dogs are not well defined. In humans, excessive exposure to the sun is often specified as the cause of melanomas, but most dog breeds are adequately protected by their coat. However, skin injuries or constant trauma due to excessive scratching or licking causes skin cells to divide and multiply frequently. As changes in genetic structures are due to cell division, the most common cancers occur in cells that depend upon multiplication to be able to function properly.
The hereditary component in the development of cancer is important in the development and progress of melanoma in dogs. An inherited mutation that is responsible for cell division can increase the risk of cancer. The genes responsible for hereditary melanoma in humans and mice have been identified. However, certain dog breeds are more prone to this type of cancer and the issue may run in families, too.
To date, neither the causes of cancer have been established nor are metastatic cancers satisfactorily treatable. Cancer is still the most common cause of death in dogs. However, a healthy dog has reliable built-in abilities to destroy abnormal cells. This means that for cancer to get a foothold, a malignant cell must either bypass these or eliminate them. The best strategy to avoid dog cancer, including melanoma, is thus to boost in-built safeguards and strengthen the immune system.