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Oral Masses in Dogs

What Are Oral Masses in Dogs?

Oral masses refer to noticeable swellings found within your dog’s mouth. It’s crucial to understand that not all instances of oral masses indicate cancer; indeed, most are non-cancerous.

As a responsible pet owner, regularly examining your dog’s mouth is essential, as prompt treatment can significantly improve your dog’s quality of life and lifespan. Biannual checkups play a vital role in early detection and intervention.


Benign tumors in dogs include the following:

Peripheral odontogenic fibromas (POFs) stand out as the most prevalent oral masses in dogs. Typically solitary in occurrence, these tumors exhibit a non-aggressive growth pattern, albeit they can attain considerable size over time.

Acanthomatous ameloblastomas, while benign and non-metastatic, display high local aggressiveness, capable of invading bone structures and displacing adjacent tissues, including teeth.

Odontomas, less frequent compared to other benign tumors, typically originate from dental cell precursors. Characterized by slow growth, they are more commonly observed in younger dogs.

Among malignant tumors are:

Melanoma, often displaying pigmentation, presents high levels of aggression with a propensity for metastasis, frequently spreading to the lungs and lymph nodes upon diagnosis.

Squamous cell carcinoma (SCC), often manifesting as red lesions due to inflammation and ulceration, tends to infiltrate underlying bone tissues.

Fibrosarcoma shares similarities with SCC, characterized by local aggressiveness but a slower rate of metastasis.

Osteosarcoma, primarily affecting long bones rather than the jaw, exhibits aggressive behavior and may metastasize to distant sites such as the lungs.

Other oral masses detected within a dog’s mouth may stem from poor dental hygiene. Periodontal disease, causing inflammation and discomfort, can lead to gingival hyperplasia, mimicking the appearance of a mass. Dentigerous cysts may arise from retained deciduous teeth, while oral papillomatosis, a viral infection commonly transmitted among young dogs, results in wart-like growths within the oral cavity.

Symptoms and Types

Not all oral masses signify cancerous growths. Fortunately, in dogs, the majority of these masses tend to be benign. However, despite their non-metastatic nature, they can still inflict significant discomfort or pain upon your dog.

You might observe a mass inside your dog’s mouth, which could be located near a tooth, attached to the gum, inside the lip, at the back of the throat, or beneath the tongue. Occasionally, the mass may become ulcerated or infected, leading to inflammation and rawness of the surrounding skin.

Additional signs to watch for include:

  • Foul breath
  • Mouth bleeding or presence of bloody saliva
  • Excessive drooling
  • Facial swelling or asymmetry
  • Pawing or rubbing at the face or mouth
  • Jaw chattering
  • Reluctance to open or close the jaw, or resistance to teeth brushing
  • Difficulty in eating, food dropping, and weight loss, particularly in advanced stages where the tumor has grown significantly or become ulcerated or infected.


The underlying causes of most oral masses in dogs remain largely unclear. However, several factors have been linked to specific tumors, including:

  • Age
  • UV damage (or other environmental factors)
  • DNA mutations
  • Genetics

Certain dog breeds demonstrate predisposition to oral masses, such as:

  • Retrievers
  • Dachshunds
  • Boxers
  • German Shepherds
  • Scottish Terriers
  • Poodles

Additionally, other masses like papillomas have been attributed to the canine papillomavirus.


The initial step in diagnosing oral masses involves visual examination of the mass. Following this, your veterinarian typically recommends a biopsy procedure, wherein a tissue core is obtained or sometimes the entire mass is removed. The collected tissue is then subjected to histopathology, enabling identification of the growth type and assessment of its behavior, including the likelihood of recurrence and metastasis.

Since biopsies are usually performed under anesthesia, dental radiographs are often advised and conducted simultaneously. Dental radiographs aid in determining the extent of tumor involvement in the bone, as malignant masses tend to infiltrate the underlying bone and displace adjacent tissues, such as teeth. Moreover, dental radiographs help identify the presence of cysts, which may displace surrounding structures without bone invasion.

Additional diagnostic tests that may be beneficial for staging and treatment purposes include:

  • Blood work
  • Chest radiographs
  • Abdominal ultrasound
  • Aspirates/biopsies of local lymph nodes
  • CT/MRI scans


The treatment approach varies based on the type of tumor, but for most oral masses in dogs, including cases of gingival hyperplasia, surgical intervention is necessary. Complete removal of the mass and sufficient surrounding tissue is crucial to prevent local recurrence. In some instances, this may entail extraction of the affected tooth (or teeth) or even partial removal of the jaw, particularly in cases of malignancy.

Following surgery, radiation therapy or chemotherapy may be administered if the margins are narrow or if surgery poses risks, such as in dogs with underlying health conditions that preclude surgical procedures or those with significant metastasis. Tumors like melanoma may require a combination of surgery, radiation, and chemotherapy for effective treatment.

In cases of oral papillomatosis, therapy may not always be necessary, as many instances resolve spontaneously within a few months. Surgical excision, laser ablation therapy, or specific medications can also induce regression of the papillomas.

Recovery and Management

After the surgical removal of oral masses in dogs, a positive outcome is typically achieved, often leading to a cure. Even if the mass isn’t entirely excised, dogs with malignant tumors can still have a favorable prognosis as removing the mass can alleviate discomfort and reduce the risk of infection. Nevertheless, it’s important to remain vigilant for signs of local recurrence, which is likely to happen.

Upon discharge, your dog will receive pain medication and recommendations for a soft food diet. Additionally, you’ll be advised to prevent your dog from chewing on toys during the healing process.

Unfortunately, melanoma presents the most challenging prognosis as it is highly malignant and tends to have already spread by the time it is diagnosed. In most cases, dogs affected by melanoma will succumb to the disease within a year.


While oral masses cannot be completely prevented in dogs, maintaining routine medical care and scheduling biannual exams can enhance the chances of early detection and appropriate treatment. As a responsible pet owner, you can contribute by implementing daily at-home dental care for your dog, including regular brushing, dental chews, wipes, or sprays and gels. This routine provides an ideal opportunity to examine your dog’s mouth for any indications of inflammation or the development of tumors.

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