Squamous cell carcinoma (SCC) is the second most common type of skin cancer in horses, and one of the most frequent forms of cancer affecting the eye. SCC tumors appear as solitary, raised, irregular masses, often ulcerated or infected, that develop around the eyelids (and third eyelids), genitals, face and ears, anal region, and other areas with minimal hair coverage and pigmentation. SCC tumors are slow-growing and are found most often in horses with white faces or markings that extend around the eyes.
Despite a large amount of research conducted on treatment for SCC, it is still a challenging condition to treat. The location of the tumor largely influences the type of treatment used. There are a wide range of currently available treatment options, however some are not universally accepted or supported by evidence based on clinical practice.
The University of California-Davis is currently conducting a clinical trial on SCC of the eye, specifically where the clear cornea meets the white of the eye, or the "limbus". This condition is referred to as limbal squamous cell carcinoma (LSCC), and is a specific form of eye cancer that affects Haflinger horse breeds, moreso than other breeds. The aim of the study is to determine the incidence of LSCC in the Haflinger horse breed, to determine the mode of inheritance if a single gene is involved, and identify candidate genes for further investigation. Haflinger horses with confirmed LSCC (must be confirmed by pathology), or horses at least 13 years of age that have never been diagnosed with LSCC are eligible to participate in the study. Click here for additional information about the research and clinical trial.