Mouth Cancer (Gingiva Fibrosarcoma) in Dogs

PetMD Editorial
By PetMD Editorial
Published: July 15, 2009

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.



Treatment depends on how large the tumor is and how much of the surrounding bone is affected by the tumor. If the tumor is very small and does not affect any of the surrounding bone, it may be removed through a technique that uses freezing (cryosurgery). Generally, a large amount of surrounding tissue must be removed along with the tumor. In some cases, this means that part of the lower jaw must be removed (hemimandibulectomy) along with the tumor. Most dogs recover well after this type of surgery.

If the tumor is too large to be removed safely, radiation therapy and/or chemotherapy may help to control the tumor and its symptoms for a while. Chemotherapy is used to give relief from symptoms when the tumor cannot be removed.

Living and Management

If your dog's tumor is removed by cryosurgery, its mouth will be sore for a while. You will need to give your dog food that is soft enough that it does not need to be chewed. This way your dog will be able to continue to eat as its mouth heals and return to feeling normal as quickly as possible. Your veterinarian can advise you on some appropriate food options.

If your dog has had surgery to remove the tumor and part of its lower jaw, it will stay in the hospital for several days after surgery until it has stabilized. It will need to be fed intravenously (IV) during this stage of recovery. Your veterinarian will monitor your dog's pain level and its ability to eat and drink. Once your dog is able to go home, it will probably need to eat soft food for some time after. Because part of the lower jaw is missing, it will take longer for your dog to eat a meal as it learns to compensate for the missing bone. In some cases, you will need to sit with your dog and assist it in eating, feeding it small amounts of food by hand. Your dog may be given pain medication to help it though the roughest part of the recovery stage. Follow your veterinarian's directions carefully regarding the medications, and the amount and frequency, to avoid overdose.

If your dog is not able to have surgery because of complications that would make it too dangerous, your veterinarian may recommend either radiation therapy or chemotherapy. Chemotherapy can either be given by IV, or directly into the tumor. Both of these types of therapy can help to reduce the size of the tumor along with the symptoms. Keep in mind that radiation therapy can also make the mouth sore, so your dog will need to eat soft food until the pain passes. Your dog may be given pain medication to help with the soreness. The drugs used for this type of treatment can sometimes cause nausea and vomiting. If your dog is not eating because of this side-effect, you may be given medications to help control the nausea so that your dog can continue to eat normally. Follow all medication directions carefully and consult your veterinarian if you should ever be in doubt. Overdose of medication is one of the most preventable causes of death in dogs.

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