Dear Dr. Thompson: We took our 8-year-old dog in for his annual check-up and our vet found a bump on his gums. She recommended we have it biopsied to make sure it is not cancerous. What options do we have if the biopsy does come back as cancerous?
Unfortunately, many oral growths in dogs can be difficult to evaluate without the help of a biopsy. What may appear to be a relatively minor lump could be potentially very serious. Most often taking a small section of tissue and sending it to a veterinary pathologist will give you an accurate diagnosis that will determine the next step in treatment.
A group of gum tumors loosely classified as epulis can range from completely benign to locally aggressive. These growths arise from the periodontal ligament, which attaches the tooth root to the jaw. Fortunately this class of tumors does not have the potential to spread or metastasize. One variant frequently involves the underlying bone of the jaw and surgery is needed to remove the affected tooth and surrounding tissue, which generally is curative. The more benign variants do not need aggressive surgical treatment unless they grow over the tooth and result in an abscess.
The most serious growths can have the potential to spread to other parts of the body, which may be life threatening, and early diagnosis is crucial. Oral melanoma and squamous cell carcinoma are the two most common malignancies of the oral cavity. Oral melanoma in dogs does not always have the classic darkly pigmented appearance that people associate with the skin cancer in people and can be easily mistaken for a benign epulis. Unfortunately, by the time of diagnosis in many dogs the cancer has spread to the surrounding lymph nodes.
Complete surgical removal is the first step in treatment. There is a new therapy for malignant melanoma in which a vaccine is given that stimulates the immune system to attack the cancerous cells, and more than 70 percent of dogs respond well to the therapy. If the diagnosis is a squamous cell carcinoma, the prognosis can be much worse. If there is no evidence of the cancer having spread, surgical removal is the best choice. Radiation therapy can be an option as well but would require a trip to a specialty center.
I hope the diagnosis is the best-case scenario and no further treatment will be needed. However, you are right to get a diagnosis so if it is more aggressive you will catch it early and have the best chance at a favorable outcome.
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