Oral & Mouth Cancers

Includes melanoma, squamous cell carcinoma, and fibrosarcoma of the mouth.

What is Oral & Mouth Cancers?

Oral tumours account for roughly 6% of canine cancers. They are often locally invasive into bone and can be advanced before owners notice them, because dogs rarely show mouth pain until eating is affected. Regular home dental checks catch these early.

Common signs and symptoms

Signs vary between dogs and can be subtle at first. Watch for the following, especially if several appear together or persist for more than a few days:

Bad breath (halitosis) that worsens over weeks
Bloody saliva or blood on chew toys
Dropping food or chewing on one side
Loose teeth in an otherwise healthy mouth
Visible mass or swelling on the gum, palate, or jaw
Facial asymmetry

Risk factors

Certain dogs are more predisposed. Understanding risk helps you screen earlier and act sooner.

Medium-to-large breed senior dogs
Heavily pigmented oral mucosa (melanoma)
Chronic dental disease

When to see a vet

Use this as general triage guidance, not a substitute for veterinary advice.

Book a routine appointment if: you notice new bad breath, bloody saliva, or any oral mass on a home dental check.
Seek urgent care if: difficulty eating, facial swelling, or heavy oral bleeding.

Diagnosis and management

Diagnosis includes oral exam under anaesthesia, biopsy, dental X-rays or CT, and staging of local lymph nodes. Treatment often involves wide surgical excision (which may include partial jaw removal — usually well tolerated), radiation therapy, and in the case of oral melanoma, the melanoma vaccine. Data referenced from the Veterinary Society of Surgical Oncology (VSSO).

Oral Melanoma

The most common oral malignancy in dogs. Aggressive, with a high rate of metastasis to lymph nodes and lungs. Treatment combines surgery, radiation, and immunotherapy (melanoma vaccine).

Oral Squamous Cell Carcinoma

Locally invasive into bone but slower to metastasise than melanoma. Tonsillar SCC is a more aggressive subtype. Surgery and/or radiation are mainstays.

Oral Fibrosarcoma

Locally aggressive, often looks less alarming than it behaves ('histologically low-grade, biologically high-grade' variants exist). Wide surgical resection is key.