In the peer-reviewed journal PLOS Genetics, University of California-Davis researchers have outlined evidence of the role that the SERPINB11 gene plays in causing Hoof Wall Separation Disease in Connemara ponies.
The inherited disease manifests itself as separation of the dorsal hoof wall along the weight-bearing surface of the hoof during the first year of life. It is characterized by a hoof wall that easily breaks and cracks, and a normal-looking coronary band.
The disease is a genetic autosomal recessive condition. Two carrier parents being bred with each other result in a one in four chance of the foal being afflicted with the distressing disease. It was announced last September that a genetic test for the disease was commercially available.
The scientists, led by Dr. Carrie Finno, carried out their work on behalf of the Connemara Pony Research Group. It began in November 2011.
The paper, titled “SERPINB11: Frameshift Variant Associated with Novel Hoof Specific Phenotype in Connemara Ponies,” describes what it says is the first genetic recessive variant associated specifically with the hoof wall. The SERPINB11 variant behind the disease does not appear to involve or affect any other organs in which the gene is expressed.
The researchers based their findings on work with 423 Connemara ponies. Among them, they found 31 affected ponies, all homozygous for the SERPINB11 gene responsible for the disease — that is, they inherited the gene from both parents.
The severity of the disease in these 31 ponies ranged from mild, where the pony was able to be maintained with frequent hoof trimming and shoeing, to severe.
Within the 423-Connemara ponies, 18.7 percent (a total of 96 ponies) were carriers – that is, they had inherited the recessive gene from one of their parents. All were unaffected by the disease.