1. Skin changes: melanoma often appears on the skin of the dog, and in the early stages black or dark lumps or spots may be observed on the skin.
2. Lump growth: melanoma is usually a fast-growing lump, and early on an enlargement of the lump may be felt or observed.
3. Signs of malignancy: In the early stages of melanoma, the lesion may be localized, but as the disease progresses, the melanoma may undergo malignant changes, which are manifested by the borders becoming blurred, the lesion becoming localized to vesicles or ulcers, or even ulcers.
4. Pain or discomfort: The dog may feel pain or discomfort in the area of the melanoma or exhibit licking and biting behavior of the lump.