Mouth Cancer (Gingiva Fibrosarcoma) in Dogs

Gingival Fibrosarcoma in Dogs

As dogs age, they sometimes develop growths in their mouths. One type of oral growth is a fibrosarcoma, a cancerous tumor derived from fibrous connective tissue. Fibrosarcomas are relatively low in malignancy, growing slowly and generally not spreading to other organs, though they do aggressively invade other tissue and bone that is near them. The most common location for a fibrosarcoma of the the mouth is in the gums (gingiva).

Dogs that are affected with fibrosarcomas are, on average, seven and a half years old, but these tumors have been seen in dogs from the age of six months to fifteen years. Larger dogs and Golden Retrievers seem to be affected more than other dogs, and male dogs more often than female dogs.

Symptoms and Types

  • Excess salivation
  • Bad breath (halitosis)
  • Loose teeth
  • Difficulty picking up food
  • Difficulty chewing food (dysphagia)
  • Blood coming from the mouth
  • A growth in the mouth
  • Weight loss


There are no known causes for gingival fibrosarcomas.


Your veterinarian will need a thorough history of your dog’s health, onset of symptoms, and possible incidents that might have preceded this condition. For example, when your dog stopped eating, when you noticed its teeth were loose, how much weight it has lost, etc. A mass or tumor in the mouth will be apparent during the physical examination, and the location of the swelling will be differentiated from the gums or the lymph nodes beneath the jawline. The lymph nodes will be examined by palpation, and if they are found to be swelled with lymph fluid, a sample may be taken by needle so that the fluid can be examined for cancerous cells. Standard tests include a complete blood count and biochemical profile to confirm that your dog’s internal organs are in healthy functioning order. Your veterinarian may also order x-ray images of the thorax (chest) to make sure that there is no evidence that the tumor has spread into the lungs. X-rays of the skull will also be taken to see if any of the skull bones have been affected by the tumor. In some cases, a computed tomography (CT) scan can be utilized to determine how severely affected the skull bones are are how far the tumor has metastasized (spread) into the bone. Your veterinarian will also take a biopsy of the tumor for laboratory analysis. This will help your doctor to determine exactly what type of tumor is in your dog’s mouth.


Examination through feeling

radiation therapy

A treatment of certain neoplasms that is administered using an x ray

lymph nodes

Small structures that filter out the lymph and store lymphocytes


Another word for the gums; the membrane around the teeth and the lining of the mouth


Condition in which eating and/or swallowing is difficult


The process of removing tissue to examine it, usually for medical reasons.

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