Genetic Mutation Causes Hoof Wall Separation Disease In Connemara Ponies by Paulick Report Staff|08.07.202208.06.2022|5:13pm10:17pm Connemara ponies can suffer from a genetic mutation causing hoof wall separation disease (HWSD), in which the hoof wall splits along its weight bearing surface. Often confused with white line disease or laminitis, HWSD differs from these conditions as the separation occurs within the hoof wall, rather than between the hoof wall and the coffin bone. Researchers at the Bannasch Laboratory, part of the UC–Davis School of Veterinary Medicine, recently discovered the genetic mutation responsible for HWSD. They suspected that the condition was autosomal recessive as HWSD-affected ponies typically have two normal parents, but begin showing signs of the condition by the time they are a year old. In autosomal recessive conditions, individuals that carry two copies of the mutated gene are affected. “Carriers” are unaffected and carry only one copy of the faulty gene, but if two carriers are bred and both pass on a copy of the mutated gene, the foal develops HWSD. The researchers used genome-wide association analysis to identify the chromosome in which the defective gene was located. The mutation was found in a gene that produces a protein called SERPINB11, but it is unclear whether SERPINB11 plays a role in the production and maintenance of normal hoof wall tissue. In a study group of more than 300 Connemara ponies, 22 had double copies of the faulty gene and showed signs of HWSD. None of the control horses carried two copies and all had normal hooves. The scientists also determined that nearly one in seven unaffected ponies carried one copy of the mutated gene. Read more at EQUUS magazine.