Hoof Wall Separation Disease (HWSD)
→ Separation of the Hoof and Hoofwall
- Unstabile, brittle hoofwall
- Inflammation of the hooves
- Hoof pain
- The first symptoms are commonly noticed within the first year.
- As the hoofwall separates from the hoof, the horse can become lame.
- Although some affected horses have minimal symptoms, the worst cases can require euthanasia because of severe pain.
Inheritance: autosomal recessive
→ The pony is only affected when both copies of the gene (hwsd/hwsd) have the mutation. Ponies with only one copy of the mutation (N/hwsd) are clinically normal carriers.
The possible genotypes are:
N/N The horse is normal, and cannot produce HWSD-affected offspring.
N/hwsd The horse is a carrier of HWSD, and can pass the allele on to approximately 50% of any offspring. If bred to another N/hwsd carrier, approximately 25% of the offspring will be normal, 50% will be carriers, and 25% will be affected.
hwsd/hwsd The horse is affected with HWSD. If bred to a normal animal, 100% of the offspring will be carriers. If bred to a N/hwsd carrier, 50% of the offspring will be carriers and 50% will be affected.
– Carriers may be bred to normal animals (N/hwsd x N/N) without any risk of producing affected offspring. The offspring should also be tested before breeding to determine if they are carriers or normal.
– Breeding two carriers (N/hwsd x N/hwsd) is not recommended due to the possibility of 25% of the offspring being affected.
– Affected animals (hwsd/hwsd) may only be paired with non-carriers (N/N) following a critical review of the breeding value of the animal
Test Information: This mutation test identifies a single base pair insertion in the SERPINB11 gene.
Finno, C.J., Stevens, C., Young, A., Affolter, V., Joshi, N.A., Ramsay, S., Bannasch, D.L.: SERPINB11 Frameshift Variant Associated with Novel Hoof Specific Phenotype in Connemara Ponies. PLoS Genet 11:e1005122, 2015. Pubmed reference: 25875171. DOI: 10.1371/journal.pgen.1005122.
Further Information is available on the OMIA website: Online Mendelian Inheritance in Animals.