HWSD is a disease that affects the hoof wall, causing it to easily break and crack
Hoof wall separation disease
Breeds known to be affected
Hoof Wall Separation Disease causes the hoof wall to easily crack and break. It is specific to Connemara ponies or their crossbreeds. In some ponies the disease is less severe, but in other cases they may need to be euthanised due to increasing pain and related infections. The symptoms generally appear within the first 6 months of life and can affect all four feet. HWSD is caused by a single base insertion in the SERPINB11 gene and is recessive, meaning only horses that are homozygous HWSD/HWSD can be affected. If a horse is a carrier (n/HWSD) there is a 50% chance it will pass the variant to its offspring, so mating to other carriers should be avoided to prevent the birth of an affected foal.
Interpretation of results
n/n: Horse does not carry the mutation associated with HWSD.
n/HWSD: Horse has one copy of the mutation associated with HWSD.
HWSD/HWSD: Horse has two copies of the mutation associated with HWSD.
Finno et al. SERPINB11 Frameshift variant associated with novel hoof specific phenotype in Connemara ponies. PLoS Genetics 2015, 11:e1005122. doi:10.1371/journal.pgen.1005122