Opening statement for Oral Tumors:
Oral tumors constitute about 6% of the overall incidence of cancer in dogs and cats. Early detection is vital to the successful treatment of oral tumors. This is why regular oral examinations are so important, especially as your dog or cat ages.
Signs of Oral Tumors:
Unfortunately, you are unlikely to see any obvious signs that your dog or cat has an oral tumor until the tumor is large. However, if your dog or cat shows any of the signs below, a complete oral examination by your veterinarian is needed:
- Drooling or increased salivation
- Facial swelling
- Bleeding from the nose or mouth
- Weight loss
- Bad breath
- Difficulty eating or swallowing
- Pain on opening of the mouth
- Loss of teeth in an otherwise healthy mouth
When an oral tumor is identified, typically the first step is to determine the type of tumor with a surgical biopsy. Generally, a biopsy can be performed under a short, heavy sedation or anesthesia. Removal of a large section of tissue is recommended in order to achieve a proper diagnosis. Oral tumors often have a large amount of associated inflammation, ulceration and necrosis, so small samples or fine needle aspirates (needle biopsies) rarely provide enough tissue for diagnosis. One can attempt to remove the tumor during the course of the biopsy (called curative intent biopsy) if the tumor has a general benign appearance or if there is little-to-no underlying tissue or bone destruction.
Imaging of any oral tumor is necessary to determine both how extensive the local tumor is and if there is any underlying bone invasion. Dental X-rays (radiographs) and CT scans can both provide information, but radiographs (the more common and less expensive option) will not detect bone loss until 40% or more of the dense outer surface of the bone (the cortex) has been destroyed. For that reason, we prefer to rely on our Cone Beam CT scanner for diagnosis and surgical planning as the sensitivity to bone loss is much higher.
The term staging refers to the process of determining if the cancer has spread to other parts of the body (or metastasized). This is more likely with some oral tumors than others, so staging will likely only be recommended for those tumors that are likely to metastasize, such as oral malignant melanoma. The most common place for oral tumors to spread is the lymph nodes and the lungs. Three-view chest radiographs or a chest CT scan are recommended to evaluate the lungs, CT again being more sensitive than radiography.
Lungs are relatively straightforward to evaluate but lymph nodes are much trickier. There are many different interconnected lymph nodes in the head and neck and cancer can spread to them in unpredictable ways. For example, although a tumor might be present on the right side of the mouth, it might drain to the lymph nodes on the left side of the head and neck. While it is still relatively common to simply test or remove the mandibular lymph node or all the lymph nodes on the same side as the tumor, this method is likely to miss metastasis in a large number of patients and subject patients to unnecessary surgery. A newer and more accurate method of determining spread to local lymph nodes involves identifying the sentinel lymph node (SLN) which is the first draining lymph node of the tumor. This method involves the use of contrast agents, dyes, and imaging and determines the status of all the other lymph nodes in the chain.
Surgery and radiation therapy are the two most commonly utilized methods to treat oral tumors and prevent their growth and spread. Of these two, we always recommend surgery over radiation therapy when possible as surgery is generally less expensive, quicker, and more curative than radiation. Additionally, large oral tumor removals such as maxillectomy and mandibulectomy (removal of portions of the upper or lower jaw bones) are generally very well-tolerated in dogs. Cats can also tolerate surgery well, but larger surgeries have more risk of post-operative complications such as difficulty eating, excessive salivation, and inability to groom.
Radiation therapy can be used as a primary curative intent treatment for oral tumors that are too large for surgical removal, and for those that don’t respond as well to radiation, it can be used for palliative care. An oncologist should be consulted in order to discuss the long-term benefits and the possible side-effects of radiation when considering this treatment option.
Chemotherapy is rarely used for the treatment of oral tumors, but for those tumors that have a high chance of spreading to other parts of the body, your dog’s or cat’s oncologist might discuss chemotherapeutic options with you. Oral tumors that are considered to be very aggressive in dogs are malignant melanoma, squamous cell carcinoma of the tonsils, and osteosarcoma.
Animal Dentistry & Oral Surgery has the experience and equipment needed to quickly diagnose and properly treat any type of oral tumor. We are always happy to work with your oncologist and primary practitioner to develop an optimal plan for your dog or cat. Rest assured, we are here for you and your loved fuzzy family member!
Reference: Liptak, J.M. Cancer of the Gastrointestinal tract. In: Withrow and MacEwen’s Small Animal Clinical Oncology, 6th Edition; 2019.