Majestic and beautiful, yes, but the Friesian horse is unfortunately at risk for a number of genetic conditions, including a newly described disease affecting the outer surface of the eye. Affected Friesians have a progressive thinning of the cornea’s surface, which can lead to a number of sequelae such as globe rupture and iris prolapse.

Recently, researchers evaluated the medical records of a number of Friesian horses with corneal lesions that were examined and treated by veterinarians in the United States and Europe.

“Based on those reports, and because affected horses were all of the same breed, veterinarians began to suspect a genetic condition like pellucid marginal degeneration (PMD), which is considered a form of corneal dystrophy, rather than trauma, for example,” explained Mary Lassaline-Utter, DVM, PhD, Dipl. ACVO, from the University of California, Davis, School of Veterinary Medicine’s Department of Surgical and Radiological Sciences.

To better characterize corneal dystrophy in Friesians and to determine whether a genetic basis for the condition exists, Lassaline-Utter and colleagues identified and examined nine Friesian horses with bilateral corneal lesions