Oral squamous cell carcinoma (SCC) arises from the squamous epithelial cells that line the surfaces of the mouth. Its behaviour varies dramatically depending on location within the oral cavity: tumours in the front of the mouth (rostral gingival SCC) tend to invade bone locally but rarely spread distantly, giving them a good prognosis with surgical removal. In stark contrast, tonsillar SCC is one of the most aggressive oral tumours in dogs, with early and widespread metastasis to lymph nodes and lungs and a very poor prognosis. Tumours at intermediate locations fall somewhere between these extremes. This location-dependent behaviour is a defining feature of oral SCC and directly guides treatment recommendations — what works well for a gingival tumour may not be appropriate for a tonsillar one.