Canine Oral Cancer

At Animal Cancer Care Clinic (ACCC), we understand that discovering a lump in your beloved dog’s mouth can be deeply concerning. Receiving a diagnosis of oral cancer can be particularly distressing. Please know that our dedicated and compassionate team is here to support you and your furry companion every step of the way. Oral cancers in dogs vary significantly in their behavior, but we have advanced diagnostic and treatment options available at ACCC aimed at effectively managing the condition, alleviating pain, and maximizing your dog’s quality of life.

What is Canine Oral Cancer?

Oral cancer refers to malignant (cancerous) tumors that originate in the mouth, including the gums, tongue, lips, tonsils, hard or soft palate, or jawbones. It is important to understand that “oral cancer” is not a single disease; several different types of malignant tumors can occur, and their behavior and prognosis vary significantly.

The most common malignant oral tumors in dogs include:

Malignant Melanoma: This is the most common malignant oral tumor in dogs. It arises from pigment-producing cells. Oral melanomas are typically highly aggressive, grow rapidly, and have a very high tendency to spread (metastasize) early to regional lymph nodes (under the jaw) and distant organs like the lungs, liver, and bone. They often appear dark but can sometimes be non-pigmented (amelanotic).
Squamous Cell Carcinoma (SCC): This is the second most common malignant oral tumor. It arises from the flat cells that line the mouth. Oral SCCs are typically locally invasive, meaning they grow aggressively into surrounding tissues and bone (especially the jaw). Their potential to spread to regional lymph nodes or distant organs is variable but generally lower than melanoma. They often appear red, inflamed, ulcerated, or cauliflower-like.
Fibrosarcoma: This is another common malignant oral tumor, arising from connective tissue cells. Oral fibrosarcomas are primarily locally invasive and destructive, often involving bone. They have a lower metastatic rate compared to melanoma but can still spread, though typically later in the disease course. They often appear as a firm, fleshy mass.
Other Rare Malignant Tumors: Less common malignant tumors include osteosarcoma (bone cancer starting in the jaw), lymphoma, and mast cell tumors.
Benign Tumors: It’s important to differentiate malignant tumors from benign oral growths, such as epulides (which are common non-cancerous growths on the gums, like fibromatous epulis or peripheral odontogenic fibroma) or gingival hyperplasia (overgrowth of gum tissue). A definitive diagnosis always requires a biopsy.

What Causes Canine Oral Cancer?

The exact cause of most oral cancers in dogs is not fully understood. However, some factors are believed to play a role:

Age: Oral cancers are generally more common in middle-aged to older dogs.
Breed Predisposition: Certain breeds appear to have a higher incidence for specific types:
- Malignant Melanoma: Cocker Spaniels, Poodles, Golden Retrievers, German Shepherds, Dachshunds.
- Squamous Cell Carcinoma: Shetland Sheepdogs, Collies, German Shepherds.
- Fibrosarcoma: Golden Retrievers.
Chronic Irritation/Inflammation: Some theories suggest chronic irritation (e.g. from chewing on certain objects, or chronic dental disease) may contribute to the risk of SCC.
Genetic Factors: May play a role in some cases.

Canine oral cancer is not contagious to other pets or humans.

Signs and Symptoms of Canine Oral Cancer:

The signs and symptoms of oral cancer in dogs can be subtle initially and often progress as the tumor grows. Many signs mimic common dental disease, making prompt veterinary evaluation important:

Bad Breath (Halitosis): A persistent, often foul odor from the mouth is a very common early sign.
Difficulty Eating (Dysphagia) or Anorexia: Your dog may show reluctance to eat, drop food, chew on one side of their mouth, or stop eating altogether due to pain or discomfort.
Drooling (Ptyalism): Excessive drooling, which may sometimes be blood-tinged or contain pus.
Bleeding from the Mouth: You may notice blood in their food or water bowl, on toys, or directly from their mouth.
Visible Mass or Swelling: A lump, ulcer, red or inflamed area, or abnormal growth in the mouth (on the gums, tongue, palate, or lips).
Loose Teeth: If the tumor invades the jawbone, teeth in the affected area may become loose, fall out, or appear displaced.
Facial Swelling or Deformity: If the tumor grows large or invades the jawbone.
Pain or Discomfort: Your dog may paw at its mouth, rub its face, become head-shy, or vocalize when yawning or eating.
Weight Loss: Due to difficulty eating or the presence of cancer.
Enlarged Lymph Nodes: You may be able to feel enlarged, firm lymph nodes under your dog’s jaw (mandibular lymph nodes).

If your dog exhibits any of these persistent oral signs, especially bad breath, difficulty eating, or a visible mass, it’s important to seek veterinary attention promptly. Early diagnosis and aggressive intervention significantly improve the prognosis for many oral cancers.

How is Canine Oral Cancer Diagnosed?

Diagnosing canine oral cancer at Animal Cancer Care Clinic (ACCC) requires a thorough approach, often under sedation or general anesthesia, to allow for a complete examination and tissue sampling:

Comprehensive Oral Examination: Our veterinarians will perform a detailed examination of your dog’s entire mouth, including all tooth surfaces, gums, tongue, palate, and tonsils. This often requires sedation or anesthesia. We will also palpate the regional lymph nodes (mandibular lymph nodes).
Biopsy (Incisional or Excisional) and Histopathology: A biopsy is essential for a definitive diagnosis of oral cancer and to determine the specific type of tumor and its grade.
- Incisional Biopsy: A small piece of the suspicious mass is removed for microscopic examination by a specialized pathologist. This is often done if the mass is large or its complete removal is not initially feasible.
- Excisional Biopsy: For smaller masses, the entire tumor may be surgically removed and submitted for histopathology, serving as both diagnosis and treatment.
Imaging of the Head (Dental Radiographs, CT Scan, MRI): These imaging studies are helpful for assessing the local extent of the tumor, particularly its invasion into the underlying jawbone (mandible or maxilla). A CT scan of the head is often a valuable tool for detailed assessment of bone invasion and for precise surgical planning. Dental x-rays may be used for specific tooth-related areas.
Regional Lymph Node Evaluation: Evaluation of the lymph nodes under the jaw (mandibular lymph nodes) is critical for checking for metastasis. This often involves palpation, and if suspicious, a fine needle aspirate (FNA) or biopsy of the lymph node.
Blood Work: A complete blood count (CBC) and serum chemistry panel are performed to assess your dog’s overall health before anesthesia and treatment.
Staging: For all malignant oral tumors, further staging tests are highly recommended to check for distant metastasis:
- Thoracic Radiographs (X-rays) or CT Scan of the Chest: To check for spread to the lungs, a common metastatic site. A CT scan is more sensitive for detecting small lung nodules.
- Abdominal Ultrasound: To check for spread to abdominal organs (e.g. liver, spleen, abdominal lymph nodes), particularly for more aggressive tumor types.

Treatment Options for Canine Oral Cancer:

At Animal Cancer Care Clinic (ACCC), our treatment approach for canine oral cancer is often aggressive and multi-modal, aiming to achieve local control of the tumor, manage pain, preserve function, and address any metastasis. The specific plan depends heavily on the tumor type, size, location, and stage.

Surgery: Surgical removal of the tumor is the primary and often most effective treatment for local control. Due to the invasive nature of many oral cancers, this can involve removing a portion of the jawbone (mandibulectomy or maxillectomy) to achieve adequate surgical margins and remove all cancerous tissue. While daunting, dogs can often adapt remarkably well to these surgeries. Our skilled surgeons at ACCC are experienced in performing these complex procedures.
Radiation Therapy: Radiation therapy is an important treatment modality for oral cancers. It may be used:
- Adjuvant: After surgery, to treat any microscopic tumor cells that might remain, reducing the risk of local recurrence.
- Primary Therapy: For tumors that are not surgically resectable, or in cases where extensive surgery is not desired.
- Palliative: To control tumor growth and significantly alleviate pain, improving quality of life. We can discuss if radiation therapy is a suitable option for your dog and coordinate with a radiation center.
Chemotherapy: The effectiveness of traditional cytotoxic chemotherapy varies significantly by tumor type:
- Malignant Melanoma: Generally considered less effective as a sole agent but may be used in combination with immunotherapy or for metastatic disease.
- Squamous Cell Carcinoma & Fibrosarcoma: Response to traditional chemotherapy is generally poor, and it is usually not a primary treatment, but may be considered for microscopic disease or metastatic disease.
- Lymphoma: If the oral tumor is lymphoma, then systemic chemotherapy is the primary treatment. Our veterinary oncologists at ACCC will discuss whether chemotherapy is recommended for your dog’s specific tumor type and stage.
Immunotherapy (Melanoma Vaccine): For oral malignant melanoma, a canine melanoma vaccine (Oncept®) is available. This is not a traditional, preventative vaccine but rather a therapeutic immunotherapy designed to stimulate the dog’s immune system to recognize and fight against the cancer cells. It is typically used as an adjuvant therapy after surgery or radiation to try and prevent or slow metastasis.
Palliative Care: For dogs with advanced disease where aggressive treatment is not feasible, palliative care focuses on managing pain, supporting nutrition (e.g. through a feeding tube if eating is difficult), and maintaining the best possible quality of life.

What to Expect During and After Treatment:

If your dog undergoes treatment for oral cancer at Animal Cancer Care Clinic (ACCC), you can expect:

Intensive Post-Surgical Care: This includes pain management, careful monitoring of the surgical site, and potentially managing a feeding tube if extensive oral surgery was performed.
Close Monitoring: Our team will closely monitor your dog’s comfort level, ability to eat, and overall recovery.
Management of Potential Side Effects: We will proactively manage any potential side effects from radiation therapy, chemotherapy, or immunotherapy.
Regular Follow-Up Appointments: These appointments will involve oral examinations, palpation of regional lymph nodes, and potentially repeat imaging studies (chest radiographs/CT scans) to monitor for local recurrence or metastasis.

Prognosis for Canine Oral Cancer:

The prognosis for dogs with oral cancer varies significantly and is highly dependent on several critical factors:

Tumor Type: This is the most important factor.
- Malignant Melanoma: Generally, has a guarded to poor prognosis due to high metastatic potential, but prognosis can be improved with aggressive local therapy (surgery/radiation) combined with immunotherapy.
- Squamous Cell Carcinoma (SCC) & Fibrosarcoma: Prognosis depends heavily on the ability to achieve complete surgical removal. If completely resected, survival can be good; if incomplete, local recurrence is common. SCC in the tonsils has a higher metastatic rate and worse prognosis than SCC on the gums.
Size and Location of the Tumor: Smaller tumors that are more easily accessible and do not involve bone generally have a better prognosis. Tumors involving the tongue base or tonsils often have a worse prognosis.
Bone Invasion: If the tumor has invaded the underlying jawbone, it significantly impacts prognosis and requires more aggressive surgery.
Presence of Metastasis: If the cancer has spread to regional lymph nodes or distant organs (especially the lungs), the prognosis is significantly shortened.
Completeness of Surgical Removal: Achieving wide, clean surgical margins is crucial for local control and improved survival for all types.
Overall Health of the Dog: A dog’s general health, nutritional status, and presence of other medical conditions can impact treatment tolerance and prognosis.

Early diagnosis and aggressive multi-modal treatment (often surgery + adjuvant therapy) offer the best chance for extending survival and maintaining a good quality of life.

We will discuss the potential prognosis for your dog based on their individual diagnosis and the chosen treatment plan at ACCC. Our goal is to provide realistic expectations while focusing on maximizing their comfort and quality of life for as long as possible.

Coping with an Oral Cancer Diagnosis:

Receiving a diagnosis of oral cancer for your dog can be incredibly difficult, as it often impacts his or her ability to eat, a fundamental part of enjoying life. Please know that the team at Animal Cancer Care Clinic is here to offer not only the best possible medical care for your dog but also compassionate support for you and your family during this difficult time.

We encourage you to ask us any questions you have and to share your feelings and concerns openly. We want you to feel informed and supported as you make important decisions about your dog’s care and how to best support their comfort and well-being. We can also provide information about resources that may be helpful for pet owners facing a cancer diagnosis.

Our commitment is to work with you to develop a treatment plan that is tailored to your dog’s needs and your wishes, while always prioritizing their comfort, quality of life, and your shared bond.

Questions to Ask Your Veterinarian:

To help you better understand your dog’s condition and the treatment options available, here are some questions you may find helpful to ask us:

What specific type of oral cancer does my dog have (melanoma, SCC, fibrosarcoma, etc.)?
What is the size and exact location of the tumor? Has it invaded bone?
Has the cancer spread to regional lymph nodes or other parts of the body (e.g. lungs, liver)?
What are the recommended treatment options for my dog’s oral cancer?
What are the potential risks and complications of surgery (including jaw resection)?
Is radiation therapy, chemotherapy, or immunotherapy (melanoma vaccine) recommended? What are its goals and potential side effects?
What is the expected prognosis for my dog with the recommended treatment?
How will my dog’s pain and ability to eat be managed throughout treatment and beyond?
Will my dog need a feeding tube? How will I care for it at home?
What is the estimated cost of the recommended treatment plan and ongoing care?
What can I do at home to best support my dog during this time?

Conclusion:

At Animal Cancer Care Clinic, we are dedicated to providing compassionate and comprehensive care for dogs with oral cancer. Our experienced team will work closely with you to develop a personalized treatment plan focused on managing the disease and maximizing your dog’s quality of life. Please do not hesitate to reach out to us with any questions or concerns you may have. We are here to support you and your cherished canine companion through this challenging journey.