One of the most common signs of melanoma in dogs is a visible swelling of the mouth or toes, according to the Veterinary Cancer Center. However, these can also be signs of less serious illnesses.
Melanomas typically develop in dogs' mouths or on their toes. Oral melanomas often have symptoms similar to gum disease or other dental problems, including drooling due to increased salivation, loose teeth and discolored gums. Dogs with oral melanomas may lose weight and be unwilling to eat. If they do eat, they may drop food as they try to chew. Inspection of the mouth may reveal a visible mass that can be black, white or pinkish. The dog's face may appear swollen, reports PetMD.
Digit melanoma symptoms can be confused with toe infections or injuries. Although swelling is often the only noticeable symptom, some dogs may lose the nail on the affected digit. The dog may limp or show signs of sensitivity when its feet are handled. A tumor may be visible, and is usually black in color. Some dogs also develop benign melanomas. These are often located on the back, head or limbs, according to PetMD. These usually present as a firm, raised mass. They are usually round and dark. Although benign melanomas are not immediately harmful, they are often removed to be safe.