What they are:
Squamous cell carcinomas typically occur in warm, sunny climates (like ours!) and often show up on non-pigmented skin like white eyelids or sheaths. They are the most common malignant skin tumours in horses, and 18% of them will spread throughout the body. These lumps often appear innocuous at first and it is easy to mistake them for bites or minor scratches. With time they will become an ulcerated area that will grow and spread into surrounding tissues.
‘Wait and see’ is not a valid option with squamous cell carcinomas. They must be treated or removed a soon as possible. If the lesion cannot be exised in surgery with a clear margin of 1cm all around it, then other treatments will definitely be needed. Many vets, regardless of the margin, will opt for combination therapy such as surgical removal and injection with chemotherapeutic agents to help prevent the recurrence of these troublesome lesion.