Cats are not always the most cooperative patients when their mouth needs examining, but routine checks of the inside of their oral cavity can yield vital health information. Most importantly, these check-ups can reveal an oral tumor that may otherwise go unnoticed until growing too large to effectively treat. Oral squamous cell carcinoma is one such oral tumor that can affect cats. Discover more about the most common oral tumor in cats, and how you can spot the mass during its earliest stages to provide the best prognosis.

What is oral squamous cell carcinoma in cats?

Oral squamous cell carcinoma is cancer of the oral cavity’s lining, including the gingiva, tongue, hard and soft palate, and tonsils. Tumors are locally invasive and can extend into the jawbones, but can also metastasize to the lymph nodes of the head, neck, and lungs. 

What causes oral squamous cell carcinoma in cats?

While no definitive cause for oral squamous cell carcinoma in cats is known, a few factors can increase development risk.

  • Smoke exposure — Cats exposed to household environmental tobacco smoke appear to have an increased risk of developing oral squamous cell carcinoma. If the owner smokes indoors, the cat is exposed to a great deal of secondhand smoke, and can groom the carcinogens off their fur.
  • Flea collar use — Poor quality flea collars may be responsible for oral squamous cell carcinoma development in cats, because the collar pesticides are close to their mouth.
  • Diet — Cats who eat canned tuna or canned cat food appear more likely to develop oral tumors, perhaps because of the nutritional differences between canned and dry food.

What are the oral squamous cell carcinoma signs in cats?

Oral tumors in cats can be difficult to detect, as cats are notorious for hiding illness signs. They are also less than amenable to regular at-home mouth examination. Signs your cat may be developing an oral squamous cell carcinoma include:

  • Weight loss
  • Reluctance to eat
  • Blood-tinged saliva
  • Blood in the food and water dishes
  • Blood on your cat’s front paws from rubbing at their face
  • Decreased grooming habits
  • Foul breath
  • Facial or jaw swelling

Unfortunately, most cats do not show any outward signs until the tumor is too large for successful treatment.

How is oral squamous cell carcinoma diagnosed in cats?

A thorough oral exam is the first step in diagnosing oral squamous cell carcinoma in cats, who generally require sedation to allow a full mouth examination. Once sedated, the entire oral cavity can be examined, and samples taken of suspicious areas. Depending on what is seen, a needle aspirate of a few cells may be taken, or a biopsy may remove tissue samples. To determine the disease’s extent, a CT scan is typically necessary. This helps ensure the tumor is fully removed and has not extended into the jawbone.

Additional diagnostic testing includes blood tests to assess overall health, and chest X-rays to determine disease spread. Needle aspirates of local lymph nodes may also be taken to rule out metastasis.

What treatment options are available for oral squamous cell carcinoma in cats?

The best treatment option for your cat depends on the size, placement, and spread of the tumor, and their overall health. Treatment options are divided into the following four categories:

  • Surgery — Oral squamous cell carcinoma tumors are locally invasive and can attack much of your cat’s jawbone. The tumor will likely return if not completely removed, so wide surgical margins are essential for effective treatment. In some cases, this means removing large portions of the cat’s jaw. 
  • Radiation therapy — If a tumor is incompletely removed, radiation therapy can help prevent or delay regrowth. Radiation therapy consists of daily treatments for several weeks, and requires general anesthesia. Palliative radiation therapy is also an option for cats with tumors that cannot be surgically removed. This therapy may slow tumor growth and is less likely to cause ulcerative side effects.
  • Chemotherapy — Chemotherapy options include injectable or oral drugs, but these therapies generally do not shrink the tumor. If a cat has a good quality of life, despite their oral squamous cell carcinoma tumor, chemotherapy can stabilize the tumor, and prolong a good quality of life.
  • Palliative care — Palliative care consists of oral pain medications and anti-inflammatory drugs, with or without radiation therapy. Administering oral medications is often difficult, because cats with tumors are sensitive around their mouths, and generally do not eat well. Feeding tubes can be placed to provide nutrition, as well as providing an avenue for administering medication. 

What side effects can be seen with oral squamous cell carcinoma treatment in cats?

Side effects depend on the treatment selected, the tumor extent, and the illness caused. In surgical cases, a feeding tube may be necessary for several weeks after surgery, or may be a permanent fixture. Chemotherapy side effects are infrequent and most commonly include temporary gastrointestinal upset and lethargy. Despite popular beliefs, cats will rarely lose their hair while undergoing chemotherapy, although they may lose their whiskers. Radiation therapy can cause vomiting, diarrhea, local skin and tissue irritation, and potential interference with surgical healing.

Cats who develop an oral squamous cell carcinoma tumor are best treated by a veterinary oncologist who can provide the most effective treatment options. However, the initial diagnosis can be made by your family veterinarian, or by scheduling a full-mouth oral exam with our Animal Dental Clinic team. Contact us if your cat is displaying oral cancer signs, such as foul breath, reluctance to eat, weight loss, and poor grooming habits.