Hoof Wall Separation Disease (HWSD) FAQ
Hoof Wall Separation Disease (HWSD) is a genetic defect characterized by a hoof wall that easily breaks and cracks, and a normal appearing coronary band. The breaks and cracks begin to occur in young ponies. In severe cases the pony bears weight entirely on the sole of the foot which can lead to severe lameness.
It is a genetic condition that is recessive. The disease will not be expressed unless both HWSD alleles are present on the specific gene. It is present from birth and cannot be cured. It can be managed although management is notoriously difficult.
Our job as a breed society is to protect the Connemara Pony. As we have a halfbred registry, we must know what the Hoof Wall status of any mare or stallion halfbred to protect the possible progeny. Now we have added Connemara Sport Horses as a registry as well. While any progeny from this registry are not registerable unless bred to a purebred or halfbred Connemara, it continues to be our ethical responsibility to know the Hoof Wall status of our CSH. We would be negligible if the horrible affliction of Hoof Wall disease were to spread to a new population of sport horses or ponies.
Testing for hoof wall separation disease is important in assisting clinicians, owners, and breeders in identifying affected and carrier horses. Breeders can use results from the test as a tool for selection of mating pairs to avoid producing affected horses.
For our ACPS registry, and now our Halfbred and Connemara Sport Horse registry (as of 2021) Hoof Wall status is required for registration. If the Hoof Wall status of both parents is N/N, the foal will also be N/N and no test is required. Otherwise a DNA test is required for registration.
UC Davis has a DNA test to determine the Hoof Wall status.
We have a Hoof Wall status list of the Connemaras and Halfbreds already tested.
If you want to breed a Connemara or Connemara Halfbred or Connemara Sport Horse and you do not know their Hoof Wall status you must find out before you breed. You can contact the breeder or check with Marynell Eyles about a DNA test. If one has not been done, Marynell will send you a form to send in to UC Davis for $40.00 to get the test.
N/N means no copy of the Hoof Wall allele to pass on to offspring.
N/HWSD means the individual has one normal allele and one HWSD allele to pass on. Statistically, the N will passed on to 50% of the offspring and the HWSD will be passed on 50% of the time.
HWSD/HWSD means the individual is affected and shows the diseased state. This individual will always pass on a HWSD allele to its offspring.
Mating N/N to N/N is always safe, no offspring will be carriers or affected.
Mating N/N to N/HWSD is also always safe. No offspring will be affected. However, 50% of the offspring will be carriers N/HWSD.
Allowing a mating of HWSD/HWSD to N/N will not produce any affected offspring but all offspring will be carriers N/HWSD.
It would not be safe to allow a mating of N/HWSD to N/HWSD as approximately 25% will be born affected HWSD/HWSD.
This means that you must know the Hoof Wall status of any mare or stallion with any Connemara in their pedigree prior to breeding to be sure that the mating will be safe.