Breed registry officials have taken steps over the last decade to reduce the number of Belgian foals born with a fatal skin disorder called junctional epidermolysis bullosa (JEB). And while veterinarians report anecdotally that they’re seeing fewer cases, a new analysis of mandatory sire screening results has spurred the registries to expand testing requirements.

John D. Baird, BVSc, PhD, professor emeritus of the University of Guelph’s Ontario Veterinary College, worked with researchers at the University of California (UC), Davis, Veterinary Genetics Laboratory to examine 10 years of data from both the Belgian Draft Horse Corporation of America (BDHCA) and the Canadian Belgian Horse Association (CBHA). He presented the team’s results at the 2013 American Association of Equine Practitioners’ Convention, held Dec. 7-11 in Nashville, Tenn.

Junctional epidermolysis bullosa is one of a large group of inherited diseases that result from a failure to produce a protein essential for skin layer adhesion. Affected foals are “characterized clinically by a fragile skin that results in ulcers and erosions following minor trauma,” he said. These diseases are named for where the level of separation takes place in the skin. Epidermolysis bullosa can occur in a variety of species, but Belgian horses experience a particular type at the level between the epidermis (outer layer of the skin) and the dermis, which is immediately beneath the epidermis. Often called “hairless foals,” Belgian neonates with JEB have large lesions on the body that appear as if the skin is missing. Baird noted that a similar condition occurs in Saddlebred foals, but it involves a different mutation in a different gene.