Oral Tumours In Cats & Dogs

Written by Shula Berg BVSc CertAVP(GSAS) GPAdvCert(SASTS) MRCVS
Clinically reviewed by Elizabeth McLennan-Green BVM&S CertAVP(SAM) MRCVS

Table of Contents

 - Overview
 - Symptoms
 - Diagnosis
 - Treatment
 - Outlook

What are Oral Tumours? 

Oral tumours are seen reasonably commonly in both dogs and cats, but unlike tumours on other parts of the body, they are often difficult to spot until they are quite large. There are many different types of tumour that can affect the oral cavity. Some are benign (not aggressive) while some are malignant (aggressive) and will spread around the body. There are also a number of tumour types that fall in between these two extremes, in which they do not spread but can be very aggressive locally. It is impossible to tell the different types of tumours apart from just appearance alone. Additionally, some masses in the mouth are inflammatory tissue and not a tumour, but can appear very similar. 

Oral tumours most commonly affect middle-aged to older animals, but can affect any breed. 

What are the symptoms of Oral Tumours?

Many oral tumours have few to no symptoms in their early stages, and may be found by chance observation. Some pets may show discomfort or difficulty eating, or excessive drooling, while others may have bleeding or a bad smell from the mouth. Less common symptoms include nose bleeds, facial swelling and weight loss. 

Some oral tumours will cause loosening of the teeth, so loss of multiple teeth in one area is suspicious. Often the tissues around the teeth will look swollen or abnormal, though sometimes this is only detected during a dental procedure. 

Which tests are used to diagnose Oral Tumours? 

The only reliable way to determine what type of oral tumour it is, is with a solid tissue biopsy. This allows the lab to examine the individual cells and how they are structured in relation to each other. This is always performed under anaesthesia, but is not an invasive procedure. 

Since many types of oral tumour will invade the bone of the jaw, it is often advisable to perform x-rays at the same time as the biopsy. This allows a rough assessment of how aggressive the tumour is, and provides valuable information when considering treatment options. It may also be recommended to take a sample of cells from the nearby lymph nodes using a needle. These are sent to the lab with the biopsy, and can help determine if cancerous cells have spread. 

Some types of oral tumour can spread elsewhere in the body. If this is the case, it is often recommended to examine the lungs prior to definitive treatment. However, this is often performed after we have the biopsy results as it will not be necessary for all tumour types. The lungs are examined using chest x-rays or a CT scan. CT is more sensitive to detect cancer spread but is not available at every clinic. Your vet will advise you on the most appropriate option. 

How are Oral Tumours treated?

Treatment of oral tumours depends on the tumour type diagnosed at biopsy. Broadly speaking, oral tumours are classed as either originating from the teeth or surrounding ligaments (odontogenic), or from the soft tissues of the mouth. 

Odontogenic tumours are generally benign, though some can be invasive and cause local bone loss. There are many different classifications of odontogenic tumour, and predicting their behaviour accurately can be challenging. Truly benign tumours (often referred to as epulides) do not need treatment and can just be monitored. Odontogenic tumours that are locally invasive are best treated with surgery. 

Tumours originating from the soft tissues of the mouth are generally more aggressive, and many are malignant. Again, many tumour types are possible but the most commonly seen are Squamous Cell Carcinoma, Melanoma and Fibrosarcoma. These tumours have often spread elsewhere in the body by the time of diagnosis. Surgery may be possible, but there is less likelihood of this achieving a cure, and additional therapy such as radiation may be required. 

Unfortunately, chemotherapy is generally not effective to treat oral tumours, though the latest research suggests that immunotherapy may be suitable to treat malignant Melanoma in the near future. Your vet will be able to advise you on the treatment options for your pet, and can consult with a specialist oncologist if needed. 


Most oral tumours will extend into the jaw bone, so to successfully surgically remove them we must remove the surrounding bone. This generally involves only a part of the bone, not the whole jaw, and is much less dramatic than it initially sounds. The procedure is known as a partial maxillectomy (upper jaw) or partial mandibulectomy (lower jaw). 

Sometimes, pets will stay in hospital for a few days post-operatively, but most will start to eat voluntarily within 48 hours and are much less bothered by the surgery than we may expect! Depending on which part of the jaw is affected, there may be some change to their appearance, however most surgeries have a very good cosmetic and functional outcome. This type of surgery is usually performed by a specialist, or a vet with a particular interest in surgery. 

Radiation therapy 

Radiation therapy is generally used for aggressive tumours that are not suitable for surgical resection, or when the entire tumour cannot be successfully removed due to its location or size. Radiation is applied to the site to eliminate remaining cancer cells. Specialist referral is needed for radiation treatment, and there are a limited number of specialist centres that can provide veterinary radiotherapy in the UK. 

What is the outlook for pets with Oral Tumours?

The prognosis for pets with oral tumours is varied depending on the type of tumour present. Odontogenic tumours are generally benign or curable with surgery, and carry an excellent prognosis. Other tumour types are often malignant and aggressive, and therefore carry a much more guarded prognosis. It is common for these tumours to have spread by the time of diagnosis, so treatment is unfortunately more likely to be palliative than curative. The exact prognosis varies with tumour type, so your vet will be able to give you a better idea of what to expect. 


Please note that the content made available on this webpage is for general information purposes only. Whilst we try to ensure that at the time of writing all material is up to date and reflects industry standards, we make no representation, warranties or guarantees that the information made available is up to date, accurate or complete. Any reliance placed by yourselves is done so at your own risk.

Page last reviewed: 20th February 2024

Next review due: 20th February 2026