October 2025
In this VETgirl online veterinary continuing education blog, Dr. Michael Balke, DAVDC, F-OMFS continues his 2-part series on oral tumors in dogs and cats. In Part 1, we explored how to approach these cases for diagnostic success. In this follow-up installment, Dr. Balke reviews the most common oral tumors in canine and feline patients, highlighting treatment strategies, prognostic factors, and referral considerations. Whether you’re aiming for a cure or managing comfort, the right plan, at the right time, can make all the difference. Missed Part 1? Check it out HERE.

Oral Tumors in Dogs and Cats (Part 2 of 2) – Treatment Options and Prognosis for Common Oral Tumors

by Dr. Michael Balke, DAVDC, F-OMFS

Oral tumors are a significant clinical concern in dogs and cats. Early detection and appropriate intervention are critical in improving outcomes and maintaining quality of life. The first article in this series discussed how to diagnostically approach oral tumors in dogs and cats. In this second article of a two-part series, we are discussing treatment options and prognosis for common oral tumors.

Malignant oral melanoma is the most common malignant oral tumor found in dogs, but is rarely diagnosed in cats.1  These tumors are highly invasive and have a high metastatic potential, mostly to the regional lymph nodes and lungs.  Wide surgical removal is the treatment of choice to obtain local control.  Radiation therapy can be used in addition to surgery if clean margins are not achieved or as a primary mode of treatment if surgery is not an option.  When combined with surgery or radiation therapy, a melanoma vaccine has been shown to increase the median survival time in some studies.  Chemotherapy has not been shown to offer a significant survival benefit.2   Cases in which the melanoma is identified and treated early, while the tumor is relatively small in size and prior to metastasis, can have a favorable prognosis (Figure 1).3

Figure 1. Canine oral malignant melanoma on the left mandibular gingiva that was able to be successfully treated with wide surgical removal of the tumor. (A: Pre op, B: Post op). Photos courtesy of Dr. Michael Balke, DAVDC, F-OMFS

Unfortunately, melanomas that are not discovered until they are larger in size make local control more difficult and the chance of metastasis much higher, giving them a guarded to poor prognosis (Figure 2).

Figure 2. Canine oral malignant melanoma attached to the buccal mucosa. This tumor was surgically resected with clean margins, but the dog eventually developed metastasis to the lungs 8 months after surgery. Photo courtesy of Dr. Michael Balke, DAVDC, F-OMFS

Squamous cell carcinoma (SCC) is the second most common malignant oral tumor found in dogs4 and the most common in cats5.  There are various subtypes of oral squamous cell carcinomas, but broadly speaking, we will discuss tonsillar vs non tonsillar.  Non tonsillar squamous cell carcinoma is often locally invasive but has a lower metastatic potential than oral melanoma.  In dogs, aggressive surgical resection of the tumor can be curative if clean margins can be achieved (Figure 3).6

Figure 3. Very large and invasive mandibular squamous cell carcinoma on a dog that had been present for 9 months prior to surgical removal. The tumor was able to be completely removed with clean margins. The owners reported an increase in overall quality of life after tumor removal. (A: Pre op, B: Post op). Photo courtesy of Dr. Michael Balke, DAVDC, F-OMFS

Similar to oral melanoma, if surgery is not an option or clean margins were not achieved, radiation therapy can be used to attempt local control.  Chemotherapy has not been shown to be an effective treatment modality, but can be used for palliative care in dogs with SCC.7 Prognosis is fair to good.  Like dogs, aggressive surgical resection can be curative in cats. Unfortunately, it is often not an option as these tumors are typically too large and invasive at the time of diagnosis (Figure 4).

Figure 4. Picture (A) and intraoral radiograph (B) of a 12-year-old cat diagnosed with squamous cell carcinoma of the left mandible. The mass was occupying most of the left mandible resulting in diffuse bony destruction and soft tissue swelling. Unfortunately, due to the advanced nature of the tumor and the cat’s declining condition, humane euthanasia was elected shortly after diagnosis. Photo courtesy of Dr. Michael Balke, DAVDC, F-OMFS

Treatment is often palliative and can include radiation therapy, non-steroidal anti-inflammatory drugs (NSAIDs) and opioids.  Prognosis is poor with median typical survival times of less than three months.8   Tonsillar squamous cell carcinoma is primarily diagnosed in dogs and is a very aggressive tumor with a high metastatic potential.  Unless diagnosed and treated early, multimodal treatment with surgery, radiation therapy and chemotherapy may extend life but is rarely curative. Prognosis is considered poor to guarded, with median survival often less than one year.9

Fibrosarcoma is the third most common malignant oral tumor in dogs and is less common in cats.  They are a highly aggressive tumor locally that rarely metastasize.  Early detection and wide surgical management can improve outcome and possibly be curative.  If complete wide removal is not achieved or surgery is not a possibility, radiation therapy can be used to help with local control.  Chemotherapy has not been shown to be effective against fibrosarcoma.  Because of the tumor’s invasive nature and high recurrence rate, it is considered to have a guarded to poor prognosis.10

The best opportunity for a successful outcome of oral tumors in dogs and cats typically occurs with early detection, accurate diagnosis and collaboration with oral surgical and oncological specialists.  When possible, a combination of surgery, radiation and adjunctive therapies offers the best chance for long-term control.  For animals that are not able to undergo curative treatment, supportive and palliative care with pain management and nutritional support should be provided.

References:

  1. Murphy BG, Bell CM, Soukup JW. Veterinary oral and maxillofacial pathology. Wiley-Blackwell, 2020, p. 130.
  2. Pazzi P, Steenkamp G, Rixon AJ. Treatment of Canine Oral Melanomas: A Critical Review of the Literature. Vet Sci. 2022;9(5):196.
  3. Carroll KA, Kuntz CA, Heller J, et. al. Tumor size as a predictor of lymphatic invasion in oral melanomas of dogs. J Am Vet Med Assoc. 2020;256(10):1123-1128.
  4. Evans SM, Shofer F. Canine oral nontonsillar squamous cell carcinoma: prognostic factors for recurrence and survival following orthovoltage radiation therapy. Vet Rad. 1988;29(3):133-137.
  5. Murphy BG, Bell CM, Soukup JW. Veterinary oral and maxillofacial pathology. Wiley-Blackwell, 2020, p.143.
  6. Fulton AJ, Nemec A, Murphy BG, et. al. Risk factors associated with survival in dogs with nontonsillar oral squamous cell carcinoma 31 cases (1990-2010). J Am Vet Med Assoc. 2013;243(5):696-702.
  7. Boria PA, Murry DJ, Bennett PF, et. al. Evaluation of cisplatin combined with piroxicam for the treatment of oral malignant melanoma and oral squamous cell carcinoma in dogs. J Am Vet Med Assoc. 2004;224(3):388-94.
  8. Bilgic O, Duda L, Sánchez MD, et. al. Feline Oral Squamous Cell Carcinoma: Clinical Manifestations and Literature Review. J Vet Dent. 2015;32(1):30-40.
  9. Mas A, Blackwood L, Cripps P, et.al. Canine tonsillar squamous cell carcinoma — a multi-centre retrospective review of 44 clinical cases. J Small Anim Pract. 2011;52(7):359-64.
  10. Martano M, Iussich S, Morello E, et. al. Canine oral fibrosarcoma: Changes in prognosis over the last 30 years?. Vet J. 2018;241:1-7.

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