Oral squamous cell carcinoma is the most common malignant tumour of the mouth in cats and carries an extremely poor prognosis. The cancer arises from the squamous epithelial cells lining the oral cavity, most frequently under the tongue (sublingual) or along the gums. It is aggressively invasive locally, rapidly destroying bone and soft tissue, and affected cats often present with drooling, difficulty eating, bloody oral discharge, or weight loss. Without treatment, survival is typically only one to two months. Unfortunately, even with aggressive treatment combinations (surgery, radiation, chemotherapy), long-term survival remains poor — fewer than 10% of cats survive one year. The cancer's resistance to treatment and the anatomical challenges of the feline mouth make this one of the most difficult cancers to manage in veterinary oncology.