Treatment and Prognosis for Melanoma in Dogs
Goals of Treating Melanoma
The primary goal of treating melanoma is to relieve the symptoms that accompany the disorder, thereby restoring the affected dog’s quality of life. Good nursing care, surgical removal, chemotherapy, radiation therapy and other medical and supportive techniques are available to treat melanoma in domestic dogs.
Melanomas of the skin usually begin and remain benign, but they can become malignant. If the affected areas of skin are bothersome to the dog, or if a veterinarian feels that a mass is suspicious, it probably should be removed by simple surgical excision. The surgeon will try to take wide surgical margins, to minimize the chance of future regrowth or spreading. This means that she will attempt to remove not only the tumor, but also an area of healthy, normal tissue all the way around and beneath the tumor. The pathologist who examines the mass and attached tissue will be able to determine microscopically whether the entire tumor was successfully removed. In most cases, the results of surgery and the prognosis for the dog are excellent, if the melanoma is benign.
Dogs with malignant melanoma need immediate treatment. Malignant melanoma is extremely aggressive and requires complete surgical removal of the affected area and much of the surrounding tissue (including underlying bone) as well, if possible given the location of the particular mass. In cases of oral melanoma, the entire jaw and maybe other areas of the mouth may need to be removed. Fortunately, reconstructive surgery can help to repair and rebuild those areas. Nearby lymph nodes may also need to be removed. If the cancer is in the nail bed, surgical excision usually includes amputation of the affected digit (toe). If sufficiently wide surgical margins cannot be achieved, the lower part of the leg may need to be amputated.
Surgical removal of melanoma is commonly followed by radiation therapy. In some cases, radiation therapy may be recommended even without surgical treatment. Chemotherapy is also recommended in many melanoma cases – with or without surgery or radiation treatment- because of the highly metastatic nature of many forms of melanoma.
In 2007, the United States Drug Administration (the USDA) conditionally licensed a vaccine for the treatment (not for the prevention) of canine malignant melanoma. This vaccine has been shown to produce immune reactions in dogs, resulting in tumor rejection and prolonged survival times. Studies about this vaccine and other potential treatment protocols for canine melanoma continue to be conducted.
The prognosis for dogs with benign skin tumors removed surgically is very good. Unfortunately, the outlook for dogs with malignant melanoma is guarded to poor. The prognosis is particularly grave for dogs with malignant oral melanoma that returns after initial surgical removal.