Oral Squamous Cell Carcinoma in the Dog and Cat
Oral squamous cell carcinoma is a common oral cancer in the dog and cat with one reference (Withrow S. MacEwen EG: Small Animal Oncology, 2001) showing a frequency of 20-30% of all mouth tumors in dogs and 70% of oral tumors in cats. Diagnosis is made via surgical biopsy and submitting a tissue sample to the pathologist.You can see from these images that oral cancer can mimic severe gingivitis and that we do not always suspect cancer until the dog or cat is anesthetized and examined more thoroughly during a dental cleaning.
This 16 year old cat had lost weight, had a foul odor form the mouth and showed evidence of difficulty in chewing food. The cat was so painful that we were not able to look in the mouth until she was anesthetized. Once under anesthesia a large suspicious looking area of gum tissue was found (arrow) which was biopsied and found to be a squamous cell carcinoma.
The treatment of choice for a locally invasive oral tumor would ideally be complete surgical resection. Unfortunately, this is a difficult decision because of the often extensive nature of these tumors coupled with the relatively small jaw size of cats. The use of radiation therapy could therefore be considered – ideally in conjunction with surgery or if that is not possible, then as single modality therapy. However, results have been discouraging. In reports of cats treated with aggressive surgery or the combination of surgery and radiation therapy, median survival times are only approximately 2-4 months. Even the addition of chemotherapy has failed to lead to significant mprovements. Because of the lack of long-term tumor control in spite of aggressive therapy, another reasonable option to consider is palliative radiation therapy. Palliative radiation therapy consists of two consecutive days of twice-daily radiation treatments and is aimed at alleviating pain, inflammation, and swelling associated with the tumor. This treatment course is repeated in one month if no disease or symptom progression is noted. We also recommend piroxicam, an oral Non-Steroidal Anti-Inflammatory Drug (NSAID) which has anti-inflammatory and analgesic properties as well as possible anti-tumor activity against carcinomas.
This 13 year old Scottish terrier was presented for its annual exam and Dr Partlow found evidence of dental tartar and a gingival mass on her routine physical exam and recommended a dental cleaning and oral health assessment. The dog was anesthetized in order to investigate the mouth and several areas of suspicious gum lesions were found (arrows) and subsequently biopsied. You can see how this tissue could mimic severe infection but in fact it turned out to be a squamous cell carcinoma. Treatment ideally consists of complete surgical resection of the tumor which often requires removal of a portion of underlying bone. If the tumor is too extensive for complete surgical excision, radiation therapy can be considered as an alternative treatment option – either to destroy residual microscopic disease or for a non-resectable large tumor. Complete surgical excision with adequately wide margins suggests a very good long term prognosis. Reports on the use of radiation alone also describe the tumor to be radiation-responsive, with median disease control times of approximately 12-18 months. We also recommend piroxicam, an oral Non-Steroidal Anti-Inflammatory Drug (NSAID) which has anti-inflammatory and analgesic properties as well as possible anti-tumor activity against carcinomas.
For more information on oral squamous cell carcinomas in cats and dogs visit the North Carolina State School of Veterinary Medicine Oncology website, from where some of the above information was taken. http://cvm.ncsu.edu/vth/clinical_services/onco/tumor_types.html