Mouth Cancer in Dogs

Kelly Roper
Have you checked your dog's mouth lately?

Mouth tumors can cause obstructions that make it difficult for pets to chew and swallow. Surgical reduction of growths is often necessary for a pet's survival, but it isn't always possible depending on the tumor's type and location. Learn more about these tumors and how they're treated.

Types of Tumors

The good news is that every tumor doesn't automatically blossom into full blown mouth cancer. According to the Pet Cancer Center, tumors can be divided into two main categories.


Benign tumors are non-cancerous growths that, in general, are easily removed by surgical means. These growths are usually well defined at the edges without the type of invasive growth into bones and other tissues that are typically seen with malignant tumors. Benign tumors also don't spread to other parts of the body.

The most common type of benign tumor found in dogs is an epulid. These tumors can be found growing on the periodontal ligament.


Malignant tumors are cancerous and are usually quite invasive to the area surrounding them. This makes surgical removal difficult, if not impossible. Malignancies also tend to metastasize or "spread" by shedding cells that migrate through the bloodstream to take hold and grow in other areas of the body. Common malignancies include:

  • Malignant melanomas: This type of tumor is the most common mouth cancer in dogs. It is very invasive, and this makes surgical removal quite challenging. It also tends to spread rapidly so by the time an owner may notice something wrong with her pet, the cancer has probably already spread to other parts of the body.
  • Squamous cell carcinomas: These tumors can grow quite aggressively but tend to remain in one localized area without metastasizing.
  • Fibrosarcomas: These tumors are very similar to squamous cell carcinomas in that they tend to resemble a bit of red cauliflower and generally don't metastasize until late in their development.
  • Acanthomatous ameleoblastomas: These tumors can be extremely aggressive and causes a lot of destruction in surrounding mouth tissues, but luckily they don't tend to spread.

What Causes Canine Mouth Cancer?

Dog with mouth cancer

Although it isn't yet possible to determine exactly what spurs the growth of cancerous cells in a dog's mouth, there are a few theories.

Inhaled Carcinogens

Carcinogens may actually be inhaled by dogs as they sniff the ground and, generally, everything else around them. Cancer-causing agents then have the opportunity to take hold and affect surrounding cells, causing the abnormal cell growth that results in cancer.

Ingested Carcinogens

Dogs may actually consume carcinogens. A recent study found a possible link between some commercial dog foods and canine mouth cancer. Some brands actually include chemical preservatives and pesticides in their formulas that may also be carcinogenic, but further study will be required to confirm these early results.

Detection and Treatment

Early detection is the key to increasing the success rate in the treatment of all mouth cancer in dogs. Sometimes it is already too late to help a pet who is only just beginning to show symptoms of being sick, so it pays to be diligent.

Owners should regularly check their pet's mouth for the following signs:

  • Abnormal lumps or growths inside the mouth
  • Abnormal overgrowth of the gums
  • Bleeding from the mouth or other discharge
  • Presence of sores or white lesions in the mouth
  • Difficulty chewing and/or swallowing
  • Weight loss
  • Pain and tenderness
  • Drooling
  • Bad Breath

According to the Pet Cancer Center, treatments for the different types of mouth tumors vary. However, the most effective treatments include:

  • Surgical removal of tumorous growths
  • Freezing of the tumor material, known as cryosurgery
  • Radiation therapy at the site

More aggressive treatments may be supported by holistic therapies including giving herbal, mineral and vitamin supplements.

Checking Your Dog's Mouth Could Save His Life

It can be devastating for an owner to learn that her pet has cancer, but routine checks of your dog's mouth will help you find any abnormalities as soon as is humanly possible. This just might increase your pet's chances for survival.

Mouth Cancer in Dogs