The most common types of cancer to occur in the canine oral cavity are melanoma, fibrosarcoma and squamous cell carcinoma. These cancers can occur in any area of the mouth, but squamous cell carcinoma is the most common mandibular cancer. The mandible (lower jaw) includes the lower jaw bone, the teeth it holds in place and the surrounding tissues. Seven to ten percent of all cancers in dogs occur in the oral area, and about 28 percent of all oral cancers are squamous cell carcinoma.
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Melanoma
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Melanoma is the most common type of oral cancer in dogs, accounting for 30 to 40 percent of all cases. This occurs in older dogs, typically 12 years or older. In the mouth, tumors tend to grow on the gums, palate and tongue. They are very aggressive and tend to metastasize, meaning that the cancer spreads to other areas. Dogs with higher pigmentation in the oral cavity are more likely to develop melanoma. They arise from melanocytes, which are the cells that produce pigment. If they are caught early, they can be surgically removed but metastasis must be evaluated and treated.
Fibrosarcoma
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Fibrosarcoma, a cancer of connective tissue, affects 10 to 20 percent of dogs with oral cancer and occurs in dogs 7 to 9 years old. It is locally invasive but does metastasize in 10 to 20 percent of all cases, so radiation is recommended following surgery. It occurs most often in the maxilla (upper portion of mouth, or palate) but can occur in the mandible.
Squamous Cell Carcinoma
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Squamous cell carcinoma in the dog's mouth occurs most often rostral to the canines, or "in front" of the teeth on the gingiva (gums) on either the mandible or maxilla. It occurs in 28 percent of all cases of canine oral cancer and usually affects large breed dogs around the age of ten. Surgery is usually a safe option as metastasis is not as common for this type of cancer, but still needs to be addressed as metastasis is possible.
Diagnosis and Treatment
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Diagnosis is dependent upon the location and type of tumor in the dog's mouth. An aspirate or biopsy is needed for diagnosis, which is required for full treatment. Excisional biopsy, which requires removing as much of the mass as possible, is a way to remove the mass while evaluating the specific type of cancer. Once identified, further treatment can be approached to address metastasis. Treatment depends entirely upon the type and location of the cancer.
Other Cancers
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Other cancers that occur in the mouth and mandible include osteosarcoma (occurs in the bone), mast cell tumor (aggressive and typically metastasize), hemangiosarcoma (malignant cancer arising from blood vessels), lymphoma (involves lymph nodes), plasma cell tumor, and multilobular tumor of bone. Other tumors can be benign, such as infectious masses or gingival hyperplasia. The types of cancer are numerous, and diagnosis and treatment must always be performed by your veterinarian.
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