horses on racetrack
Thoroughbred horse image by Rennett Stowe

Statement Regarding the Warmblood Fragile Foal Mutation in Thoroughbreds

Statement from Dr. Rebecca Bellone, Director of the Veterinary Genetics Laboratory, regarding the Warmblood Fragile Foal mutation in Thoroughbreds:

There are no reported cases in the scientific literature to substantiate a link between the Warmblood Fragile Foal mutation and bleeding disorders or poor bone formation in the Thoroughbred. Our laboratory did identify the allele for Fragile Foal in the Thoroughbred breed, but it was determined to be at a very low frequency (less than 4 percent). Furthermore, in Warmbloods, it has been shown to only behave in a recessive fashion. This means that for a horse to be affected that it needs to be homozygous, or have two copies of the mutation. We have not identified any Thoroughbreds who are homozygous for the Fragile Foal mutation. Based on all of the available data, it is highly unlikely that this mutation has anything to do with bleeding or breakdowns. 

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