Squamous cell carcinoma is the most common oral tumor in cats, and accounts for approximately 10% of all feline tumors. So far, all attempted treatments have met with limited success and limited survival times. This study will use PET-CT before and after stereotactic radiosurgery (SRS) to evaluate the primary tumor and to detect spread of the tumor (metastasis). PET-CT provides a combination of a metabolic scan (the PET portion) as well as a detailed CT scan that is good for anatomic and structural detail of organs. SRS is a type of radiation therapy that allows for fewer days of anesthesia as the treatment is delivered in several larger doses instead of smaller doses over several weeks. The post treatment scan will be used to evaluate response to treatment, and will be compared to biopsies. This study will provide multiple benefits. It will allow evaluation of a new imaging modality in the veterinary profession and give information on the efficacy of PET-CT for staging this particular type of cancer. Additionally, it will provide information about tumor response to SRS and the appearance of tumors post-SRS on PET-CT scans. The data gained could assist in the treatment planning of cats with this difficult-to-treat cancer, by better detecting metastasis and evaluating tumor response to this treatment regimen. This is a pilot study and will, it is hoped, provide information that will lead to further developments in the fields of veterinary PET-CT, SRS, and oral squamous cell carcinoma.