As soon as I examined Penny's lower jaw I knew it spelled trouble. Her owner had only just become aware of a swelling present on her lower gum and had presented her to me very soon after. I arranged for her to be admitted that morning for biopsy of the lump and 4 days later we were discussing the results in the consulting room.

She had been diagnosed with squamous cell carcinoma. This is the most common tumour of the oral cavity or mouth. Tumours may arise on any portion of the gums. The age of affected animals ranges from 5 to 15 years, with an average age of 10.3 years. A greater number of females than males are affected with an increased incidence found in Irish setters.

Squamous cell carcinomas may arise from any portion of the gums, but the majority are found in the very front portion of the jaws. Most tumours, as in this case, are between 2 cm and 4 cm by the time they are presented for clinical examination.

Invasion of the underlying bone by the tumours causes loss of teeth and in some cases a pathologic fracture of the bone. Excess salivation, bleeding, and a necrotic odour originating in the oral cavity are apparent where the tumour has been present for some time.

Fortunately, because of the poor lymphatic drainage from this area, squamous cell carcinomas rarely spread elsewhere. Recurrence of the tumour at the site of surgical excision is common unless there has been adequate excision involving removal of a portion of the affected jaw.

For that reason, and after careful discussion with her owners, "Penny" had 3 inches of her jaw removed along with the cancer.

"Penny" has, thus far, been an exemplary patient - eating her dinner with her newly designed chin within 24 hours of returning home. We are hopeful that with this early surgery her long term outlook is excellent.

Unfortunately, in Britain, oral squamous cell carcinoma kills at least 1400 people each year with nearly two thirds of patients with this cancer dying of their disease. The poor prognosis for oral cancer in Britain reflects the large proportion of patients who have advanced disease by the time they are referred for specialist treatment. The message from "Penny" is simple "If in doubt get it checked out!"

Terry Dunne BVMS, Cert SAO, MRCVS

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