Mouth Cancer in Dogs

Undifferentiated Oral Cavity Tumors in Dogs

Undifferentiated oral tumors in dogs are usually found on the roof of the mouth or around the upper teeth. They grow very quickly, involving the bone and tissue near them, and they metastasize quickly and easily to other areas of the body. They are some of the most difficult types of cancer to treat. These tumors are usually seen in large dog breeds between the ages of six months and twenty-two months old. It is uncommon for young dogs to get tumors, but on rare occasions it does happen. One type of tumor that is found in dogs is an undifferentiated malignant oral tumor, where an undifferentiated tumor is one that cannot be determined by a simple biopsic analysis.

Symptoms and Types

  • Excessive drooling
  • Bad Breath (halitosis)
  • Difficulty chewing (dysphagia)
  • Blood coming from the mouth
  • Weight loss
  • Loose teeth
  • Growth in the mouth (oral mass)
  • Occasionally, swollen glands in the neck (enlarged lymph nodes)
  • Swollen or deformed areas on the face near the eyes


There are no known causes for cancer of the mouth.


You will need to provide a thorough history of your dog's health leading up to the onset of symptoms. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis. During the examination, the doctor will make a close examination of the inside of your dog's mouth to see if there is a growth, and will palpate (examine by touch) your dog's neck and face to check for enlarged lymph nodes. The veterinarian may also want to take a fluid sample from the lymph nodes to determine whether there are cancerous cells there. X-ray images of your dog's chest may show whether any growth in the mouth has spread to the chest, and x-rays of your dog's head will also be taken to determine how far the mass has spread into the tissue and bone of the mouth and head. A simple biopsy of the neoplastic tissue will be taken to determine exactly what kind of tumor is present.

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