INTERNATIONAL (Editor’s introduction) In recent weeks, a little-known genetic disease has claimed headlines in the United States following an announcement by Hilltop Farm that one of their stallions, Sternlicht (2010: Soliman de Hus - Rhapsody x Rascalino) – a great- grandson of the legendary Donnerhall – had been removed from their 2018 breeding roster as he had tested positive as a carrier of WFFS. ‘Warmblood Fragile Foal Syndrome is an inherited systemic connective tissue disorder that is found in Warmblood horses. Foals can have extreme skin fragility that lacks tensile strength and is often characterized by tearing or ulceration from normal contact with surroundings. Limb joints are extremely lax, affected foals cannot stand normally, and they must be euthanized soon after birth’.

At the time this edition of BN was completed, news and commentary were still emerging with regard to WFFS, so this article is not a definitive analysis but an understanding of information from deductible facts from research and provided by third parties, to date.

What is WFFS?

Warmblood Fragile Foal Syndrome (WFFS) is an autosomal-recessive trait, meaning a foal can only be affected if that foal inherits the disease from both parents. Parents that are carriers do not have any symptoms associated with WFFS. However, they will pass on a copy of the defective gene to their off- spring 50% of the time whether bred to a carrier or a non-carrier and regardless of the foal’s gender. If two carriers are bred, the foal has a 25% chance of being affected (a death sentence) and a 50% chance of being a carrier.

Our understanding is that in March 2012, a mare gave birth to a foal with all the symptoms currently associated with WFFS, and was at first thought to be a carrier for a different genetic disease, such as Hereditary Equine Regional Dermal Asthenia (HERDA, which was discovered in 2007). When she was found to not be a carrier, research of her and some of her relatives led to the identification of the genetic anomaly responsible for WFFS.

Chronology

• 2013: A genetic test for Warmblood Fragile Foal Syndrome Type 1 (WFFS), developed by Nena Winand, PhD, of Cornell University in Ithaca, New York, became commercially available...

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