News have recently appeared through various channels concerning WFFS, a genetic defect of connective tissue found in warmblood populations. Signs of the disease include abnormally thin and fragile skin, hyperextension of limb articulations, hematomas, premature births, and others. Newborn foals have to be euthanized as this condition, unfortunately, is untreatable.
WFFS is inherited as an ‘autosomal recessive defect’ which means that both male and female horses are equally affected and that two copies of the mutation are needed to cause this fatal disorder. Horses that carry one copy do not show any WFFS defect but can, as ‘carriers’, transmit the mutation to 50% of their offspring. Mating of two carriers provides a 25% chance of producing WFFS foals.
The incidence of carriers in the Warmblood Horse world is estimated by scientists at 9-11%, some say 10-15%!
The WFFS mutation occurs in warmblood horse populations that include nearly all major European horse breeds such as Hanoverians, Selle Francais, KWPN, Oldenburg, Westphalians, Trakehners, Holsteiners, etc. etc. and their cross breeds.
So what should warmblood horse breeders do now to make responsible breeding decisions, i.e. to ensure that their own stallions and/or broodmares are free of this defect and do not transmit the fatal mutation to their offspring and/or to outside warmbloods?
AWR has teamed up with UC Davis to offer WFFS testing for all their registered and DNA typed warmbloods without having to send in another hair sample which makes it very simple. There is a test order form available on the AWR website; alternatively, test orders can be called in. WFFS tests can also be ordered in conjunction with the DNA typing of newly registered warmbloods.
Mare owners planning to obtain semen from foreign or US-based/bred stallions should request proof that the chosen stallion is NOT a WFFS carrier.
AWR will keep you informed as things develop. Please contact us directly if you have questions.