Ocular Squamous Cell Carcinoma

Did you know that there is a genetic test for Ocular Squamous Cell Carcinoma in Haflinger horses? It has also recently been validated in Belgian Draft horses, Rocky Mountain Horses, Connemara Ponies and at a low frequency in warmbloods.  

Squamous cell carcinoma is a common eye cancer in horses. We often see this cancer on the eyes or eyelids of horses because they get a lot of UV exposure from the sun. A mutation was discovered by researchers at UC Davis in the gene DDB2. This gene is responsible for repairing UV damaged DNA. Horses with 2 copies of the mutation are much more likely to develop this cancer because their body cannot recognize and repair the UV damaged DNA.

Testing for this mutation can educate breeding and management decisions. If a horse is positive (2 copies of the DDB2 mutation and denoted as R/R) but doesn’t have any cancer yet, we  recommend strong UV protection and close monitoring.