Dark pigmented areas or moles on dog skin can be normal or melanomas. It is common for dogs and cats to have dark pigmented areas of the skin, typically in the tongue, gum and eyelid tissue. These pigmented areas are not necessarily cause for concern as they are normal for some dogs.
Canine melanoma is a type of cancer that occurs in the skin, mouth, nail bed, foot pad and eyes. It can appear as dark brown to black lumps or large, rapidly growing masses. However, some melanomas do not have the dark pigment colour of most melanomas. Any noticeable sign of swelling or increase in size of lymph node could indicate metastasis (spread) of melanoma.
Canine melanomas can be benign or malignant. Skin melanoma is usually benign while other melanomas in the mouth, toes and eyes are more likely to be malignant. Nevertheless, benign melanomas must be monitored as they can potentially become malignant. A proper diagnosis of melanoma is done through a biopsy, where a small bit of the tumor is removed for analysis. This determines the stage of the cancer and rate of metastasis.
The best treatment for melanoma is surgical removal of the tumor and surrounding tissue, and radiation. If malignant melanoma has spread to other parts of the body, the dog’s chances of surviving is low. The prognosis is poor if the dog already has melanoma metastases or oral melanomas. Benign melanoma that has been surgically removed has better prognosis.
Consult your vet if you notice dark pigmented areas or moles on your dog skin becoming bigger and/or bleeding.