Canine skin cancer may appear in photographs as scaly or crusty lesions, discoloration under the tail or mouth tissue that appears different than other areas of the mouth. Other skin cancer signs include new growths or skin that does not heal, adds CanineCancer.com.
The most common types of canine skin cancer include malignant melanoma, squamous cell carcinoma and mast cell tumors, according to WebMD. Malignant melanoma affects the pigmented skin cells called melanocytes. Dogs can develop these tumors anywhere they have hair, and these tumors may be genetic. Squamous cell carcinomas are firm and may look like a wart. Sun exposure may cause this type of tumor, and most dogs develop them on their abdomens or around their genitals. Mast cell tumors have a rubber-like texture and may ulcerate in aggressive cases. These tumors develop on dogs' legs 25 percent of the time, and typically occur on the body's trunk.
Systemic symptoms of canine skin cancer may include vomiting, diarrhea, lethargy, appetite loss and coughing,notes CanineCancer.com. Dogs may also have enlarged lymph nodes. Owners should contact a veterinarian if they see skin color change, discharge from a nipple or tumors that bleed easily. Treatment options include surgery, radiation, chemotherapy, cryosurgery or photodynamic therapy.