Warmblood Fragile Foal Syndrome

20th February 2019

What is Warmblood Fragile Foal Syndrome (WFFS)?

It’s an inherited systemic connective tissue disorder characterised by a lack of skin tensile strength. Affected foals will display skin ulceration and tearing, from contact with normal surroundings. In addition, lesions may also be found on the gums and mucous membranes and limbs are lax and hyperextensible. Particularly fetlocks can be most dramatically affected, preventing foals from standing normally. If carried to term, the affected foal won’t survive long after birth, or will have to be euthanised on humane grounds as there is no cure for the disease. 

Since WFFS is an ‘autosomal recessive’ trait, a foal can only be affected if it inherits the disorder from both parents. Horses with just one copy of the defective gene are considered ‘carriers’ and do not have any symptoms associated with WFFS, but have the ability to pass on the gene. If a carrier is mated to another carrier, it is possible for the foal to inherit two copies of the defective gene and, if born, exhibit signs of WFFS.

We do recommend breeders test their mares and stallions to identify carriers, but it’s very much worth noting that even if identified as a carrier, a mare or stallion does not necessarily lose value for breeding nor does it diminish its positive contributions to the breed; rather, identifying carriers simply ensures that mating with other carriers can easily be avoided, thereby preventing needless foal deaths, financial loss, and heartbreak.


Hair samples (pulled not cut) can be submitted directly to Animal Genetics UK in St. Austell in Cornwall PL25 3LB. 


Simon A Stämpfli MRCVS