Melanoma is a cancer that comes from cells on the body that produce a dark brown pigment. That dark brown color is called melanin in scientific terminology. Dogs can get melanoma on the toenail, skin and, most commonly, the mouth (oral melanoma). While oral melanoma is not common in cats, it is one of the most common oral cancers in dogs.
No direct cause of oral melanoma has been found. Dogs with black or dark brown gums and black hair coats may be at a higher risk. This cancer can be found in any breed, but it is more common in the cocker spaniel, German shepherd, poodle, dachshund and golden retriever. Middle-age or older dogs (average age 10-12) are at a greater risk.
With oral melanoma, the main finding is a tumor inside the mouth. The tumor may be black or pink. Bad breath, bleeding from the mouth, face rubbing, lack of appetite and trouble chewing or swallowing are the most common signs.
Metastasis (spread) of the cancer to a nearby lymph node (gland) is possible. Some oral melanomas can be diagnosed by using a needle to remove very small pieces of the tumor and examining the tumor cells under a microscope (cytology). The process of finding
where the melanoma has spread is called staging the cancer. In some cases, X-rays, a CT scan or an MRI is done to establish the extent of tumor growth and spread.
Surgery to remove the tumor is the main treatment. If any tumor cells are left, they have the ability to spread to lymph nodes, lungs and bones. Following surgery, radiation therapy, which blasts the tumor with intense energy to kill tumor cells, may be recommended. A vaccine that causes the dog’s own immune system to kill melanoma cells has been used as an additional treatment after surgery to remove the tumor.
Prognosis for oral melanoma is poor. Even with aggressive treatment of surgery, radiation and vaccine, many dogs do not make a full recovery.
Dr. Allani Delis is a veterinarian at St. Francis Pet Clinic.