The word "cancer" is not something a dog owner wants to hear when bringing his or her pet to the vet. However, cancer can affect dogs just as easily as it can affect people. Tumours can appear in a dog's mouth, and they can be either benign or malignant. When they are malignant, veterinarians consider it oral cancer, and the cancer can spread quickly if left untreated.
According Dr. Daniel A. Degner, Board-certified Veterinary Surgeon, six per cent of all cancer tumours in dogs appear in the oral cavity. Canine oral cancer is the fourth most prevalent cancer among dogs. The best way to treat tumours in the mouth is to have them surgically removed, preferably when the tumours are still small. Once a veterinarian performs surgery, he can perform a facial reconstruction using bone grafts to restore the dog's jaw.
Oral epulis does not spread to other parts of the body. Three types of oral epulis tumours exist: fibromatous epulis, ossifying epulis and acanthomatous epulis. Respectively, these tumours are on the margin of the gums, deeper into the gum line, and at the ligament that holds the tooth root to the bone. A veterinarian can surgically remove each of these tumours with a high rate (>95%) of curing the animal. Locally invasive malignant tumours are located deeper in the jawbone and may spread to other parts of the body. Veterinarians must treat these two types of tumours (fibrosarcoma and squamous cell carcinoma) with radical surgery and radiation therapy to destroy the cancer. However, if the tumour is located closer to the back of the mouth or in the tonsils, the chance of the cancer spreading increases.
Melanoma and osteosarcoma are two diseases where the tumours are malignant and likely to metastasise. The only way to rid the dog of this tumour is through surgery. However, chances are high that the dog's cancer will have already spread to the lymph nodes by the time the veterinarian diagnoses the disease.
The size of the tumours, as well as the stage of cancer, plays a role in determining how long a dog has to live once diagnosed. The median survival rate for a dog with a melanoma tumour of less than 2 cm is 511 days. A larger tumour yields a median survival rate of 164 days. In addition, if the tumour has not spread, a dog may live up to two years, while a dog with cancer that has spread has a shorter outlook. The location of an osteosarcoma tumour also plays a role in survival time. If the tumour is located in the lower jaw, the chances of survival are much higher than if it were located in the upper.
Veterinarians use different types of surgery to remove a tumour from a dog's oral cavity, including maxillectomy (removal of the upper jaw) and mandibulectomy (removal of the lower jaw). Radiation therapy following surgery helps prevent the cancer from spreading, although it does not help with cancer that has already spread since it is a local treatment. Veterinarians can use chemotherapy in conjunction with surgery. It is important to note, however, that no official studies exist as to the effects, either good or bad, of chemotherapy drugs on dogs with this type of cancer.