Mouth Cancer In Cats: Causes, Symptoms & Treatment

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Mouth cancer in cats

If your cat suddenly begins refusing food and acting uncomfortable around the mouth, there can be several possible causes for this change. In most cases, these signs are caused by treatable dental disease.

In some cases, however, oral pain and reluctance to eat can be caused by an oral tumor. Finding, diagnosing, and treating oral tumors will require partnering with your cat’s veterinarian.

What Is Mouth Cancer In Cats (Feline Oral Squamous Cell Carcinoma)?

Oral cancer accounts for approximately 10% of feline cancer cases and is the third most common site of cancer in cats. Oral cancer leads to the formation of harmful swellings or other lesions within the oral cavity, along the gums, palate (roof the mouth), or within the throat. Squamous cell carcinoma is the most common oral cancer in cats.

Causes Of Mouth Cancer In Cats

Causes of mouth cancer in cats

The most common type of oral cancer is squamous cell carcinoma. These represent about 70% of oral tumors in cats.

There are several different types of tumors that can develop in the mouth of a cat. Not all of these tumors are cancerous. Oral masses in cats may be caused by inflammation, infection, or even trauma.

The most common oral cancer in the cat, by far, is squamous cell carcinoma. Approximately 70% of oral tumors in cats are squamous cell carcinomas.

These tumors grow from the lining of the oral cavity, including the gums, tongue, palate, and tonsils. Squamous cell carcinomas are a significant medical problem, because they tend to be locally invasive. Although they rarely metastasize (spread distantly), they often invade the underlying law bones (mandible and maxilla), making complete removal difficult.

Other common causes of oral tumors in cats are fibrosarcomas, osteosarcomas, and odontogenic tumors. Fibrosarcomas arise from the connective tissues within the mouth, often from the jaw bones. Osteosarcomas arise solely from bony tissues, such as the jaw bones. Odontogenic tumors arise from the tissues making up the teeth.

No one knows why some cats develop oral tumors. It is suspected that environmental contaminants, such as cigarette smoke and chemicals found in flea collars, may play a role; however, this has not been proven.

Symptoms Of Mouth Cancer

Mouth cancer symptoms

While some mouth cancers are visible, other symptoms can indicate mouth cancer, including bad breath and difficulty eating.

Oral tumors are painful, especially during eating. The first sign of an oral tumor is often a reluctance to eat, accompanied by weight loss. Some cats may act painful when chewing, but in many cases, owners attribute the decrease in appetite to nausea, a need to change the food, or other factors. Cats don’t always show the obvious signs of pain that you would expect, such as pawing at their mouth or acting uncomfortable.

In many cases, growing oral tumors begin to bleed. You may notice that your cat is drooling thick, ropey, blood-tinged saliva. You may also notice small drops of blood saliva around your cat’s food and water bowl, on your cat’s bed, or in other places your cat likes to rest. Your cat may have blood on his or her front paws, from attempting to groom away the bloody saliva from the mouth.

As oral tumors continue to grow, you may notice that your cat has bad breath or halitosis. Your cat’s body may also begin to smell unpleasant, as the saliva is spread across the body with grooming.

It’s important to note that all of these symptoms can also be associated with dental disease. Gum inflammation and dental infections can also lead to difficulty eating, oral bleeding, and foul breath. The only way to distinguish dental disease from an oral tumor is a thorough veterinary workup.

Diagnosis Of Mouth Cancer In Cats

Oral tumors can be found in one of two ways. Tumors are often found early, during routine veterinary care. This is the ideal scenario because is more effective when tumors are small. In other cases, however, oral tumors are not detected until the mass is causing significant clinical signs and negatively affecting the cat’s quality of life.

The first step in diagnosing an oral tumor is a thorough physical examination, including an oral exam.

Your veterinarian may be able to get a brief look in the mouth while your cat is awake, but a thorough examination requires sedation or general anesthesia.

In most cases, your veterinarian will recommend general anesthesia, because this will not only allow an examination of the mouth, but also allow your veterinarian to address issues that may be found during that examination (whether they are masses or diseased teeth that require extraction).

Before anesthesia, your veterinarian will perform pre-anesthetic bloodwork. This bloodwork allows your veterinarian to look for underlying diseases that might affect your cat’s anesthesia.

Based on the results of the bloodwork, your veterinarian will develop a detailed treatment plan for your cat. Your cat will receive a combination of injectable anesthetic drugs and inhalant anesthetics, delivered via a breathing tube.

Once your cat is anesthetized, your veterinarian can perform a thorough oral exam, looking for oral tumors or any other abnormalities.

Any time a mass is found in the mouth, even if it is found during a routine dental cleaning, the mass should be biopsied. If the mass is small, excision can be performed at the time of biopsy. If the tumor size is larger, however, oral masses often cannot be completely removed in a single surgery.

Instead, your veterinarian will remove just a small section of the mass for the pathologist to examine and then plan further treatment based on the results of this biopsy.

Biopsy results are typically available approximately one week after surgery.

Your veterinarian will call you with these results and discuss further recommended treatments.

If your cat is diagnosed with an oral squamous cell carcinoma, next steps might include tests to look for metastasis, such as performing fine needle aspirates of your cat’s lymph nodes, radiographs (x-rays), and computed tomography (a CT scan) to assess the bony involvement of your cat’s mass.

Depending on the results of these staging tests, your veterinarian will likely refer you to the oncology department of your local veterinary referral hospital.

Mouth Cancer Treatment And Prognosis

Prognosis of Mouth Cancer

The prognosis for a cat with mouth cancer depends on the type of tumor involved and how advanced it is at the time of diagnosis.

The treatment and prognosis of oral cancer in cats is dependent on two factors: the type of tumor involved and how advanced the tumor is at the time of diagnosis.

Oral squamous cell carcinoma generally is associated with a poor prognosis, regardless of treatment. According to North Carolina State University, cats with oral squamous cell carcinoma survive an average of two to four months with treatments such as surgical removal, radiation therapy, and chemotherapy.

Less than 10% of cats with oral squamous cell carcinoma survive to one year. In general, cats in which the tumor is diagnosed and treated earlier are expected to have better outcomes than cats whose cancer is diagnosed at a later stage.

Other oral tumors, such as fibrosarcoma, osteosarcoma, and odontogenic tumors, are associated with longer anticipated survival times than squamous cell carcinoma. The first step in treating these tumors is typically surgery, which may be followed by radiation and/or chemotherapy.

In some cases, palliative radiation may be used to keep a cat comfortable and extend his or her lifespan, even if the cancer cannot be cured.


If your cat is showing signs of an oral tumor, prompt diagnosis and treatment is essential. While the prognosis for squamous cell carcinoma is not good, other oral tumors can exist and earlier diagnosis will mean that you have a greater likelihood of successful treatment.

Frequently Asked Questions

How long does a cat live with mouth cancer?

There are several different types of oral cancer, each of which has a different prognosis. The most common type of oral cancer in cats, squamous cell carcinoma, has a median survival time of two to four mons with treatment.

What does cancer in a cat's mouth look like?

The appearance of feline oral cancer can vary significantly, depending on the type of cancer and how far advanced the cancer is. In most cases, oral cancer will be visible as a swelling on the gums, law, palate (roof of the mouth), or in the tonsils.

How common is mouth cancer in cats?

Oral tumors are relatively common in cats. While not all oral tumors are cancerous, approximately 10% of feline cancer cases occur as an oral cancer.

What causes oral cancer in cats?

No one has definitively determined the cause of oral cancer in cats. It is suspected that environmental contaminants may play a role, especially given the frequency with which cats lick their coats, but this has not been proven.

About Dr. Cathy Barnette, DVM

Dr. Barnette is a veterinarian and freelance writer based in Florida. Her 14 years of experience in small animal clinical practice have allowed her to witness firsthand the communication gaps that often exist between pet owners and members of the veterinary team. Her goal is to create engaging content that educates owners, empowering them to make the best possible decisions for their pets. Dr. Barnette has two cats of her own, in addition to a dog and a pet dove.

7 thoughts on “Mouth Cancer In Cats: Causes, Symptoms & Treatment

  1. Lesley

    I find the picture of the cat during surgery, with it’s mouth held open with a metal spring/screw quite horrific. It’s well known that holding a cat’s jaw open as wide as this…in fact any more than 2cm is dangerous as can cut the flow of blood to eyes and brain! It can cause blindness in cats.
    There are many studies about this and recommendations to vets.
    Please remove this picture as may give impression that usng such instruments is ok.

    1. Mallory Crusta

      Hi Lesley, thank you for commenting! We have decided to remove the image shown in the article. To clarify, it is not recommended that a mouth gag be used for a long period of time. Since the cat in the image is not intubated, the mouth gag was likely only placed there for a quick minute under light sedation or, sadly, the cat may have already been euthanized when the photo was taken. Again, we have chosen to remove the image. Thank you for your input.

  2. whitney d butler

    I wanted to say Thank you for the article. My cat who is over 18 was diagnosed yesterday with mouth cancer and I took her home. After listening to the dr. and reading this it is time to bring her in. It will kill me inside but it is better than watching her suffer. This came on suddenly so anyone who see the drooling that’s the sign. I wish I knew its been a few weeks with that I thought it was a tooth then said it must be an infection so I brought her in and the dr said her tong is being pushed as it is a fast growing tumor.

  3. Roger Mew

    Hi. we have 7 cats, having lost one the other week however, he was poisoned when about 1 year and the vet reckoned he would only survive for about 2 years, he died in my wife’s arms aged 12! We have another, 14 and she has some moth ulcers, I am hoping that it is not serious eg cancer. She is part of our family and is my little girl, having lost 1 this year, and having this one pull a muscle in her leg we really would like her to be OK. She is on Anti biotic and drugs to remove the problems with the chewing so we hope that that is the curative as they do get mouth problems. So I am praying.

  4. Susan

    My 18 year old cat died this week and my vet said it was most likely oral cancer. About a month ago I spotted heavy drooling and he was clearly unwell, he had had bad breath for a while too. Took him to an emergency clinic but it was my vet who saw the issue and told me that it was either an infection or cancer. When the nasty sore on the roof of his mouth didn’t get better after a full course of antibiotics they said that confirmed cancer. It was heartbreaking but when they told me the surgical options I knew I couldn’t put him through that so chose to keep him comfortable as long as possible.


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