| Contents |
|---|
| Hoof Wall Separation Disease (HWSD) |
| Summary |
| Understanding the Results |
| Disease Name and Genes |
| Inheritance |
Hoof Wall Separation Disease (HWSD)
Summary
Hoof Wall Separation Disease (HWSD) is an inherited condition observed in Connemara ponies. Affected animals show separation and breaking of the dorsal hoof wall along the weight-bearing surface of the hoof during the first year of life. Loss of the structural integrity of the hoof makes affected horses unable to support their weight effectively. Chronic inflammation often leads to laminitis, a debilitating condition in which the bone separates from the hoof wall. This causes extreme pain and disability, often requiring euthanasia. While the condition is not fully penetrant (some affected horses have a less severe form of the disease), there is no effective treatment for horses that are strongly affected.
About 15% of Connemara ponies are carriers. Carriers are unaffected.
Date of Last Update: 04/02/2016
Results
Understanding the Results
Results of the genetic test for HWSD are presented as shown below.
| Hoof Wall Separation Disease (HWSD) | ||
|---|---|---|
| N/N | Clear | This horse tested negative for HWSD. |
| N/HD | Carrier | Both the normal and mutant alleles are present. This horse is positive for the HWSD mutation but will not develop symptoms. |
| HD/HD | Affected | This horse carries two copies of the HWSD mutation and will develop Hoof Wall Separation Disease. |
Disease Name and Genes
Hoof Wall Separation Disease (HWSD) is associated with the insertion of a single C in the fifth exon of SERPINB11. The insertion alters the two amino acids following position 168, then introduces a termination codon that truncates 55% of the predicted protein (SERPINB11 c.504_505insC).
Inheritance
Hoof Wall Separation Disease (HWSD) is caused by a recessive variant of the SERPINB11 gene. The recessive allele is commonly abbreviated as HD, with the dominant wild-type allele abbreviated as N.
Carriers of the recessive allele (N/HD) have no symptoms of the disease. If two carriers are bred, each foal has a 25% chance of having two copies of the normal allele (N/N), a 50% chance of being a carrier (N/HD), and a 25% chance of being affected (HD/HD).
If a carrier of the recessive allele (N/HD) is bred to a normal horse (N/N), each foal has a 50% chance of having two copies of the normal allele (N/N) and a 50% chance of being a carrier (N/HD).
