Mouth Cancer (Melanocytic) in Dogs

Mouth cancer in canines is not uncommon. Melanoma is the tumor type that is seen most often. Melanoma in the mouth refers to the abnormal growth of tissue in the mucosa of the oral cavity. If your dog has melanocytic mouth cancer, there will be a growth typically seen on the lips and gums. The rate of growth is often rapid. Tissue death is always a concern, as is the chance of metastasis (often to the bone in the jaw). Melanocytic cancers can be benign or malignant; when found in the mouth they are most often found to be malignant.

Melanocytes are pigment-producing cells. Mouth cancer of the melanocytic type is a neoplasm of the thin tissue which lines the oral cavity; melanocytic cells are typically mucus producing.

Symptoms of a melanocytic cancer in your dog may not appear until the tissue growth has become quite advanced. Signs of a problem may be seen with some or all of the following symptoms.

• Drooling
• Loose teeth
• Reluctance to partake in food
• Bad breath (halitosis)
• Bleeding from the mouth
• Discharge from the nose
• Swollen face
• Swollen lymph nodes
• Swallowing may be an issue in some cases
• You may see a mass on the tongue, hard palate, or gums, or a pigmented growth on the lips

As in human cancer diagnosis, the underlying reason as to why tissues and cells grow abnormally is not fully known. Mouth cancer is documented to be predisposed in Dachshunds, Golden Retrievers, Poodles, and Scottish Terriers, and is known to be mostly an affliction of older dogs (though younger canines are not immune to oral melanomas).

The veterinarian will begin with a physical examination of your canine companion which will include looking at the oral cavity, including the teeth, tongue, palate, and gums. Your pet’s lymph nodes will be checked as well; the training and experience that the veterinary caregiver has may enable them to feel the swelling that could be present.

Blood analysis is a standard diagnostic procedure, done to evaluate the general health outlook of your pet. Further testing related to verifying mouth cancer are biopsy of tissue, and fine needle aspirate (most likely of both the lymph nodes and the growth). Imaging tests may include skull radiograph, CT scan or MRI (to identify exact mass location and spread), and chest radiograph to see if the cancer has spread to the lungs.

The therapy that your veterinarian chooses to use will be based on evidence such as tumor location, the age of your pet, the stage of the cancer, and whether there has been a large amount of spread. Because mouth cancer can be highly invasive and the tumor may be hard to reach and excise completely, full resolution of the cancer may not be possible.

Options could include surgery (which may involve removing some of the jawbone if the cancer has invaded there as well), radiation, chemotherapy, cryosurgery (application of extreme cold to the point of freezing in hopes of destroying cancerous tissue), or a combination of therapies. Palliative care may be the best option for some pets. No matter which treatment you and your veterinarian discuss, the fact that recurrence is common should be carefully considered.

The prognosis for your pet will highly depend on at what stage the tumor was discovered and whether there was a spread of cancerous growth elsewhere in the body.

If your pet had surgery to excise the melanocytic growth, he will need to rest in a quiet area after he returns home. Exercise will be limited, and soft food will be necessary for a few weeks until the veterinarian gives the okay for a return to your dog’s normal diet. You must carefully monitor your pet’s condition, watching for excessive bleeding and swelling. Alert the clinic immediately if you have concerns or feel that your pet’s behavior indicates that he is not recovering as he should. If the veterinarian found the tissue growth to be malignant, your pet’s recovery in the long-term will include checking for a recurrence of the mass, especially if the abnormal tissue was in an area that was hard to reach. It should be noted that benign tissue changes are also known to recur.