Common Oral Tumors in Dogs

Oral tumors account for 6% of all tumors in the dog.  Approximately 45% of oral tumors in dogs are malignant, with a concern for spread to additional body systems.  A major challenge with oral tumors is simply knowing if one is present. Unless daily toothbrushing is a habit, detection may not be as obvious as a tumor on the outside of the body. 

Oral tumors are classified as benign or malignant. They may affect the gums, teeth, tongue, and oral mucosa, as well as maxillofacial bone.  The occurrence of an oral tumor becomes more frequent with age.  If an oral mass is detected, the following information should be gathered:

• Determining tumor cell type by incisional biopsy
• Obtain full mouth intraoral dental radiographs. 

This information will aid in determining whether the oral tumor has the potential for metastasis. 

Symptoms associated with oral tumors typically include but are not limited to the following:

1. Facial swelling
2. Oral malodor
3. Mobile teeth
4. Decreased appetite
5. Oral bleeding
6. Oral pain
7. Weight loss
8. Non-healing recent dental extraction site

It is important to note that the above clinical signs may be representative of chronic and acute or chronic periodontal disease. Below is an overview of types, symptoms, diagnosis, treatment options, and prognosis for oral tumors in dogs.

Types of Oral Tumors in Dogs

Oral tumors in dogs are divided into two categories: benign and malignant. Benign tumors may be inflammatory or odontogenic in nature. Odontogenic refers to arising from tooth structure. 

1. Benign Oral Tumors

• Gingival hyperplasia. Gingival hyperplasia manifests as gingival overgrowth and is composed of fibrous tissue. They are seen more commonly in brachycephalic breeds such as bulldogs, pugs, and boxers. The rostral or front part of the oral cavity is most affected. Gingival hyperplasia occurs in humans who are open mouth breathers. The chronic exposure of air to the oral cavity may predispose the oral tissues closest to the mouth opening to forming reactive tissue as a protective barrier. In dogs with shorter muzzles, i.e., brachycephalic, a shorter nasal passage, will trigger respiration through the mouth as a compensatory measure. Certain medications, such as cyclosporine and amlodipine, may incite gingival hyperplasia. Treatment involves the surgical removal of the exuberant tissue, which is called a gingivectomy. Surgical treatment is followed up by routine tooth brushing to minimize reoccurrence. 

 

 

 

 

 

 

 

• Focal fibrous hyperplasia. Reactive gum tissue may occur in response to chronic periodontal disease.  Surgical treatment is successful. This may affect a single or multiple teeth. Routine dental care and oral home care are beneficial in preventing reoccurrence. 

 

 

 

 

 

 

 

• Peripheral Odontogenic Fibromas (POF): These tumors originate from the tissues around the teeth and usually affect one tooth. They are slow-growing, and excision is curative. In some cases, the tooth associated with the mass tends to be removed to avoid recurrence. 

 

 

 

 

 

 

 

• Papillomas: These are wart-like growths caused by a virus (canine papillomavirus) and are more common in young dogs. They often resolve on their own but may require treatment if they grow large or cause discomfort. They may manifest if the immune system is taxed with any concurrent health imbalance. Common sites of occurrence are the tongue and oral mucosa. 
• Canine acanthomatous ameloblastoma (CAA) This is a slow-growing, expansile tumor that occurs more frequently in medium to large breed dogs. It is locally invasive and detected commonly near the incisor or canine teeth, although it may also occur affecting cheek teeth. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Treatment involves surgical removal or radiation. The former has a high rate of success with rare reoccurrence. Surgical removal involves the removal of the tumor and an area of surrounding tissue to achieve clean margins. Margins are important to minimize the incidence of reoccurrence. 

2. Malignant Oral Tumors

• Malignant Melanoma. This is the most common malignant oral tumor seen in dogs. It may present pigmented (melanotic) or non-pigmented (amelanotic). It is seen in all breeds but may occur more frequently in cocker spaniels. The site of occurrence is anywhere in the oral cavity but is more often noted in oral mucosa near the back of the mouth.  Malignant melanoma commonly metastasizes to the lungs and regional lymph nodes. Treatment often involves multiple modalities, including surgical excision, radiation, and follow-up chemotherapy. Consultation with an oncologist, in addition to an oral surgeon, is recommended. 

• Squamous Cell Carcinoma (SCC):  This is the second most common malignant oral tumor seen in dogs. It is often ulcerative and proliferative in appearance. It often will rapidly invade bone. Oral bleeding is a common symptom, and it is commonly mistaken for periodontal disease. Treatment involves surgical excision and radiation therapy, among other emerging treatment modalities.  Consultation with an oncologist, in addition to an oral surgeon, is recommended. 

*A papillary variant may occur, which is not considered malignant, and surgical excision is expected to be curative. An oncologist consultation is typically not needed. 

 

 

 

 

 

 

• Fibrosarcoma (FSA). Fibrosarcoma is the third most common malignant oral tumor seen in the canine oral cavity. It is seen more frequently in larger breed dogs such as retrievers. It often presents as a raised, broad-based mass and involves bone as well as oral mucosa. Treatment involves surgical excision with radiation therapy. Biopsy results can be unrewarding, and a repeat biopsy may be needed with cone beam CT or conventional CT imaging for detection.  Reoccurrence may occur despite surgical excision. Consultation with an oncologist, in addition to an oral surgeon, is recommended. 

Conclusion

Oral masses can be challenging to detect and identify. An anesthetized exam with full mouth dental imaging and a biopsy is recommended if an oral mass is present or suspected. Due to the limited amount of tissue in the mouth and frequent involvement of some tumors in the surrounding bone and tissue, a biopsy is recommended first prior to a more significant surgery.  At Montana Pet Dentistry and Oral Surgery, a healthy and comfortable oral cavity is our passion. You can reach us at (406) 599-4789 to schedule a consultation and discuss your canine companion’s oral health concerns.

 

Images used under creative commons license – commercial use (11/22/2024) Image by congerdesign from Pixabay