Squamous Cell Carcinoma in Dogs

Lili Duda, VMD
Last Modified: November 1, 2001

Dear OncoLink "Ask the Experts,"
My chocolate lab has been diagnosed with squamous cell carcinoma. The tumor is on the front left side of his mouth directly above a tooth. His first diagnosis was a papilloma. It grew back and his last biopsy was determined to be squamous cell carcinoma. Radical surgery to partially remove part of his jaw is being recommended by our vet here. I have read conflicting information about this type of cancer and I am confused as to which type of treatment is best.

Can you please help clarify?  
Thank you.

Lili Duda, VMD, Editor of the OncoLink Veterinary Oncology Section, responds:

Squamous cell carcinoma is the second most common malignant oral tumor in dogs. It tends to be locally invasive but is unlikely to metastasize. Typically the regional draining lymph nodes are evaluated via a fine-needle aspiration cytology, and the lungs are evaluated with chest radiographs (X-rays). If there is no evidence of metastasis (spread of the tumor beyond the primary site) then surgery is the preferred treatment option and can be curative if the entire tumor is removed with clean surgical margins. This entails removing the visible tumor along with ALL its microscopic extensions, or "roots" into the underlying tissues and bone. This is why the surgery involves removing part of the jawbone. Dogs actually do very well with partial removal of either the upper or lower jaw, and the results are also cosmetically quite acceptable to most owners. Radiation therapy is an alternative treatment for dogs in which surgery is not an option. Radiation therapy is also used following surgery if there is concern that residual tumor has been left behind.

Because there was conflicting biopsy reports between papilloma and squamous cell carcinoma (which can have some similar microscopic appearances), it may be worthwhile to consider a second opinion by another pathologist who can review both biopsy samples.