Acanthomatous Ameloblastoma in Dogs: Diagnosis, Treatment & Prognosis

Canine acanthomatous ameloblastoma (CAA) is a type of benign oral tumor that affects dogs. CAA can affect any dog, but it is more frequently observed in dogs aged 6-10 years old. Additionally, breeds like cocker spaniels, golden retrievers, and shelties appear to be more susceptible to developing this condition. This tumor growth was previously referred to as an acanthomatous epulis. In this article, we will explore the various aspects of acanthomatous ameloblastoma in dogs, including its types, signs and symptoms, diagnosis and staging, treatment options, and prognosis for affected dogs.

 

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Types of Acanthomatous Ameloblastoma in Dogs

Canine acanthomatous ameloblastoma (CAA) is divided into two types: solid and multicystic.

• The solid type is the most common form of acanthomatous ameloblastoma, and it is characterized by solid masses composed of neoplastic cells within the jawbone. Neoplasms are growths that occur when cells divide abnormally quickly and can be either cancerous or benign.
• The multicystic form of acanthomatous ameloblastoma is much less common, and it consists of cystic spaces that are filled with neoplastic cells.

Acanthomatous Ameloblastoma is a gingival tumor that originates from the odontogenic epithelium, the tissue cells that form teeth. It primarily affects the jawbones of dogs, particularly the mandible (lower jaw) and occasionally the maxilla (upper jaw). This tumor is considered benign because it rarely metastasizes to other parts of the body. However, it can be locally invasive, leading to significant damage to the mouth including teeth and jawbones if left untreated.

Signs & Symptoms of Acanthomatous Ameloblastoma in Dogs

While there are no specific subtypes of acanthomatous ameloblastoma recognized in dogs, the tumor can present with some variation in appearance. Some tumors may be nodular or multilobulated (having several lobes), while others appear as a diffuse, infiltrative mass. Despite the variation in appearance, the underlying biological behavior remains similar.

The signs and symptoms of acanthomatous ameloblastoma can vary depending on the location in the mouth/head and the extent of the tumor within the oral cavity. Common signs include:

• Red, “angry” gingiva (gums)
• Facial swelling: One of the earliest and most noticeable symptoms, often affecting the mandible (lower jaw)
• Oral bleeding: Blood may be observed in the saliva or on chew toys. As this mass is very friable, it can bleed easily. Trauma from chewing on toys will often result in minor blood loss.
• Difficulty eating: If the mass is large or in the path of the chewing process, dogs may experience pain or discomfort while chewing or swallowing food
• Loose or missing teeth: The tumor’s invasive nature can cause teeth to become loose or fall out
• Excessive drooling: Increased saliva production may occur due to the mass effect or from discomfort in the mouth
• Bad breath: Foul odor may be present due to secondary infection or necrotic (dead or dying) tissue
• Sometimes, these tumors are found incidentally when you or your veterinarian examine your dog’s mouth.  In these cases, your dog may show no clinical signs.

 

Diagnosis & Staging of Acanthomatous Ameloblastoma

To diagnose canine acanthomatous ameloblastoma, a veterinarian will perform a comprehensive examination. As it is important to rule out other oral tumor types, the following diagnostic procedures that typically are recommended include one or more of the following:

• Physical examination and routine bloodwork including complete blood count (CBC) and a chemistry profile.
• Biopsy and/or fine needle aspirate (FNA) of enlarged lymph nodes. These samples will be examined microscopically to identify if any cancer cells are present.
• Urinalysis
• CT scan of the oral cavity, head, and neck
• Chest radiographs to assess the lungs and heart if anesthesia and surgery are necessary or to assess for metastatic disease in the event that this is a different, malignant form of oral cancer. Thankfully, CAA doesn’t usually spread.

Other oral masses that should be considered include: amelanotic melanoma, fibrosarcoma, squamous cell carcinoma, adenocarcinoma, osteosarcoma, infection, carnassial tooth abscess, bone cyst, lymphoma, plasmacytoma to name a few.

If malignant cancer cells are found, the next step is staging the cancer to determine how invasive it is and where it has spread. Again, CAA doesn’t usually spread to other parts of the body but left untreated it can be quite invasive locally and cause your canine issues.

Treatment Options for Canine Acanthomatous Ameloblastoma

The treatment approach for acanthomatous ameloblastoma depends on several factors, including the tumor’s location, size, invasiveness, and the overall health of the dog. Primary treatment options include:

1. Surgery: Surgical removal of the tumor is the primary treatment modality. For surgery to be successful, all of the CAA cells need to be removed. As this tumor can be deep within the bone, depending on the tumor’s extent, this may involve partial mandibulectomy (removal of a portion of the lower jaw) or maxillectomy (removal of a portion of the upper jaw). In some cases, reconstructive surgery may be needed to restore normal function of the jaw and appearance. Dogs do well despite this big surgery. At times, the surgeon may choose to only debulk the mass – remove the main part of it, knowingly leaving cells behind, in an attempt to preserve the integrity of the jawbone.
2. SRT/Radiation therapy: In cases where complete surgical removal is challenging or impossible or is not elected, radiation therapy may be used as the primary treatment. It can also be used in combination with surgery to achieve tumor control. After a debulking surgery, radiation therapy can treat the affected bone to target the cancer cells that were left behind thereby reducing any chance of recurrence while preserving the jawbone. Today, liquid fiducial markers can be used in areas where surgery has taken place to help target radiation therapy to the precise location of the removed tumor to improve the chances that all residual cancer cells are destroyed. A patient may need 1-3 treatments of SRT/SRS or 16-18 treatments of conventional RT (CFRT).
3. Chemotherapy: There have been some studies on intralesional chemotherapy (bleomycin) for canines with CAA. Response rate, side effects and recurrence should be discussed with your medical oncologist.
4. Palliative care: In cases where surgery or radiation therapy is not feasible due to the tumor’s advanced stage or the dog’s overall health, palliative care focuses on alleviating pain, managing symptoms, and maintaining a good quality of life.

The Prognosis for Dogs with Acanthomatous Ameloblastoma

The prognosis for dogs with acanthomatous ameloblastoma can vary depending on several factors, including the tumor’s size, location, invasiveness, and the choice of treatment. Generally, if diagnosed and treated early, the prognosis is more favorable. Dogs that undergo complete surgical excision with clean margins often have a great long-term prognosis. The same holds true for dogs receiving radiation therapy. However, recurrence happens in some cases which is why regular monitoring and follow-up visits are extremely important. For those who decline therapy, the mass will continue to grow, at times causing the roots of teeth to loosen, teeth fall out as well as causing difficult eating, bad breath and possible discomfort.  Thankfully, some of these tumors will grow very slowly.

To sum up, acanthomatous ameloblastoma is a type of benign oral tumor that tends to grow aggressively in the jawbones of dogs. Early recognition of the signs and symptoms, prompt diagnosis, and appropriate treatment are essential for the best possible outcome. If your dog has recently been diagnosed with acanthomatous ameloblastoma, please don’t hesitate to reach out to our Pet Advocate Team at 833-738-4376 – it’s a free and valuable resource for any pet parent who is trying to learn more about their pet’s cancer. We wish you and your pet all the best for a quick and healthy recovery.