Mouth Cancer in Cats

What Is Mouth Cancer in Cats?

Cancer is unregulated and abnormal cell growth, usually resulting in masses or tumors. When cancer occurs in the tissues of the mouth, it's usually very aggressive.

Mouth tumors occur in approximately five out of every 1,000 cats. Studies estimate that 3–12% of malignant (cancerous) tumors in cats are found orally, making mouth cancer the fourth most common cancer in cats. Up to 85% of oral tumors are malignant.

It’s not unusual for mouth cancer in cats to be advanced before it’s noticed, and many tumors are deeper and larger than they appear. Some oral cancers are slow-growing, and cats may show few symptoms. Other types are aggressive and can quickly spread (metastasize) to your cat’s lungs, jawbone, and lymph nodes, leading to a poorer outcome.

Cats who were diagnosed with the most common type of oral cancer and not given treatment had a median survival time of 1.5 months.

Types of Mouth Cancer in Cats

There are 22 types of mouth cancer in cats. However, some are more common than others. These include:

• Squamous cell carcinoma (SCC)—SCC is the most common mouth cancer in cats and makes up about 65% of oral tumors. Oral SCC can be aggressive and often invades the mandible or maxilla (lower or upper jawbone).

• Fibrosarcoma—Fibrosarcomas develop in connective tissue and are commonly found in the gums. Fibrosarcomas are typically slower growing but can invade nearby healthy tissue.

• Adenocarcinoma—Adenocarcinomas are relatively uncommon in cats. These tumors usually originate in the salivary glands and often spread to the lymph nodes.

• Chondrosarcoma—Chondrosarcomas originate in the cartilage of the oral cavity. These tumors are slow-growing and may appear to be noncancerous, but eventually destroy nearby tissue.

• Ameloblastoma—Ameloblastomas originate from the tissues that form teeth. While rare, these tumors can be highly invasive when they are cancerous. If they can be removed completely, they usually have a good prognosis.

Symptoms of Mouth Cancer in Cats

Symptoms of mouth cancer in cats may include:

• Bad breath

• Drooling

• Panting

• Tooth loss (most associated with SCC)

• Weight loss

• Facial swelling

• Bulging of the eye

• Bleeding from the mouth

Causes of Mouth Cancer in Cats

There is no single known cause of mouth cancer in cats. Several factors—including environment and genetics—likely contribute to a cat’s risk of developing the disease.

One study comparing cats with oral SCC to those without the disease found that cats who wore flea collars were five times more likely to develop oral SCC than those who did not, and cats who ate mostly canned food, particularly canned tuna, were three times more likely to develop SCC. Additionally, cats who lived in households where they were exposed to secondhand smoke were two times more likely to develop SCC.

Mouth cancer is more common in older cats—the average age of diagnosis is 12 years old—although it’s possible for younger cats to develop the disease.

One study found that of 146 cats with oral tumors, 88.4% were European shorthairs, and reporting suggests that Siamese cats are more likely to develop adenocarcinoma.

Males and females are equally likely to develop mouth cancer, although there is evidence that gingival fibrosarcoma (oral tumor affecting the gums) is more prevalent in male cats.

How Veterinarians Diagnose Mouth Cancer in Cats

You can prepare for your cat’s veterinary appointment by taking pictures of the tumor and writing down any symptoms they have. This can help you document changes in the tumor’s appearance and ensures you don’t forget anything that would aid in a diagnosis.

You can also review your cat’s medical records and make sure the vet has them, especially if your cat has a history of tumors or oral issues.

To obtain a diagnosis of mouth cancer in cats, your cat’s veterinarian will start with a physical exam. They may also perform a fine needle aspirate (FNA) or biopsy to diagnose the tumor’s type. FNA involves inserting a needle into the tumor, gathering cells, and viewing them under a microscope. A biopsy is more invasive and involves removing a piece of the tumor to examine it under a microscope. The tissue is often sent to a veterinary pathologist for a more thorough review.

Mouth tumors are often larger than they appear and can mimic less serious conditions, so additional tests may be recommended. Further testing may include X-rays of the head and advanced imaging such as computed tomography (CT) or magnetic resonance imaging (MRI). Both CT and MRI are ideal for determining the tumor’s extent and whether it can be removed surgically.

Treatment of Mouth Cancer in Cats

Surgery is typically recommended for cats with mouth cancer but is often unsuccessful because oral tumors can be deep and difficult to remove.

Aggressive surgery like lower jaw removal (mandibulectomy) may be needed to get all of the tumor out. If successful, some patients can live years after surgery.

Radiation can decrease a tumor’s size and relieve pain, but regrowth is typically rapid once radiation is completed, necessitating additional rounds of treatment. Radiation may be ineffective for deeper tumors that cannot be penetrated.

Chemotherapy may not be useful for a single tumor in one location and is more likely to be prescribed for cancer that has metastasized, or spread to other parts of the body.

A combination of treatments may be most effective. For example, radiation can help control regrowth of tumors after surgery, and chemotherapy can help treat cases that have spread.

When a cure is not possible, palliative care can improve your cat’s quality of life. Your veterinarian may suggest several options, such as:

• Anti-inflammatories, such as piroxicam, to help with swelling and pain

• Pain medication, such as buprenorphine

• Appetite stimulants, such as mirtazapine and cyproheptadine

• A temporary or permanent feeding tube

Recovery and Management of Mouth Cancer in Cats

Following treatment, your veterinarian will communicate with you about aftercare instructions, a recovery timeline, and future appointments. Here are some ideas of what you can expect.

Cats who receive surgery will be sore, and those who undergo a partial or full jawbone removal may stay in the hospital for several days.

Once home, there are many ways you can support your cat’s recovery from surgery:

• Put them in a small, quiet space, and keep food, water, and a litter box nearby.

• Switch to soft foods. If your cat gets a feeding tube, your veterinarian may suggest a liquid diet.

• Exercise patience. Your cat may need to be hand-fed as they adjust to physical changes involving their mouth.

Your cat’s mouth may also be tender after radiation therapy, and soft food can be helpful.

Chemotherapy can cause side effects such as nausea and vomiting. Be sure to monitor your cat and let their vet know if side effects become severe.

Regardless of treatment, always give medications as prescribed, prioritize follow-up appointments, and call your vet if you suspect anything abnormal.

Items that may be helpful for your cat’s recovery include:

• A high-calorie soft food

• A comfortable waterproof blanket

• An enclosure pen

• Feeding syringes

Prevention of Mouth Cancer in Cats

Although there are few ways to prevent mouth cancer in cats, regularly taking your cat to the veterinarian and routine dental prophylaxis (professional cleaning) can result in an earlier diagnosis and better treatment outcomes.

Though definitive links remain unclear, exposure to cigarette smoke, flea collars, and canned tuna have been connected to mouth cancer, and limiting exposure may reduce your cat’s risk.

If possible, brush your cat’s teeth regularly to maintain their oral hygiene and to notice any changes in their mouth.