Mouth Cancer in Dogs

Dogs are prone to many abnormal growths of the tissue inside the mouth and gums. Many of these are benign (not cancerous), although they should be removed to prevent further growth. However, malignant (cancerous) growths may also appear, and if not treated swiftly may spread throughout the body, causing fatal illness. Owners who notice any abnormal swelling or discoloration of their pet’s mouth should contact a veterinarian as soon as possible.Oral cancer is an abnormal growth of the tissues in the oral cavity, most commonly one of three malignant subtypes of tumor: melanoma, squamous cell carcinoma, and fibrosarcoma. Malignant tumors pose a serious threat to health and should be removed promptly, often in conjunction with radiation therapy.

• Abnormal swelling of gums, tongue or soft tissue
• Abnormal discoloration of gums, tongue or soft tissue
• Swelling of the muzzle or face
• Extreme and unusual bad breath (halitosis)
• Refusal or reluctance to eat
• Excessive saliva production beyond normal drooling
• Swollen lymph nodes

• Exposure to carcinogens over lifespan
• Inflammatory viral infections
• Genetic predisposition

Owners should periodically inspect their pet’s mouth for swelling, abnormal growths and discoloration. Sometimes petting can reveal swollen lymph nodes or lumps, which should be promptly reported to a veterinarian.

The veterinarian will make a visual inspection to rule out trauma-induced swelling and irritation (e.g. from chewing on a rawhide toy or bone), and will perform a biopsy - removing a small piece of tissue for laboratory testing. An accurate, laboratory-verified diagnosis is essential for effective treatment. There are many individual varieties of cancer, but in general, melanoma can appear nearly anywhere while squamous cell carcinoma commonly involve the gums or tonsils. The veterinarian will also examine the lungs and lymph nodes to ensure the cancer has not spread.

The veterinarian will likely schedule your dog for surgery to remove the tumors, and if they are large or of certain types, will recommend radiation therapy as well. Many cancers, if caught early and accurately identified, are cured by surgical removal. In general, non-tonsil squamous cell carcinoma is minimally invasive and if caught early can be cured with surgery. Unfortunately, melanoma and fibrosarcoma are more aggressive, and may re-occur after surgery.

Many dogs make a full recovery provided their owners follow the veterinarian’s instructions, which will vary based on the location of the tumor, the extent of the surgery and the type of cancer. In general, rest and close observation by the owner are the best recovery actions, in addition to the proper administration of any medication.