Fragile foal syndrome: manifestations, heterozygous advantage and the future of breeding policies.

Abstract

Scientific interest in relation to Fragile Foal Syndrome (FFS) has proliferated in the last decade, but before this, many clinical cases were attributed to other similarly presenting equine neonatal disorders. It was thought that FFS-affected foals were mainly miscarried throughout gestation, but recent study results suggest that often, foals are born alive and die shortly after birth. FFS is proposed to have originated as long ago as the Godolphin Arabian, but the definite derivation of the mutant allele is unconfirmed. The discovery that FFS is present in 11-30% of Warmbloods and 2-3% of Thoroughbreds is likely due to balancing selection because of human interference in equine breeding. However, the discovery has catalysed research and resulted in the formation of hypotheses proposing that heterozygous horses have an athletic advantage. Now, studbooks face a novel era of balancing the demand for successful competition horses, whilst actively promoting positive equine welfare.