Fragile foal syndrome


Good news!

Your horse is clear of fragile foal syndrome and does not have this gene mutation.   

Your horse cannot pass on this mutation. There are no breeding or performance implications.  

What is fragile foal syndrome?

Fragile foal syndrome is a genetic disease that causes skin lesions, hyperextensible limb joints and fetlock anomalies, which prevent affected foals from standing normally.  

The forelimbs, neck and abdomen are the area’s most afflicted, and if the foal survives birth, they will develop serious secondary infections over the following days and suffer from escalating pain. Since the disease is incurable, affected foals are usually humanely euthanized shortly after birth.  

Genomic Details

Fragile foal syndrome is caused by a gene mutation in the PLOD1 gene on chromosome 2. This gene is involved in the formation of collagen needed for soft connective tissue in the horse’s body, such as the skin and tendons, as well as blood vessels and internal organs. Without proper collagen formation, the skin becomes thin and tears.

The mutation that causes fragile foal syndrome is a switch in one of the four base pairs that make up a DNA molecule. Guanine (G) is replaced by Adenine (A) changing the PLOD1 gene. Therefore, a horse’s genetic result for fragile foal syndrome is one of three possibilities:

  • G/G: Normal. Does not have the disease. Does not have the mutation.

  • G/A: Carrier. Does not have the disease. Carries one gene mutation from one parent. This might be passed to their foal.

  • A/A: Affected. Has the genetic disease. The horse has inherited a gene mutation from each parent. One mutation will be passed to their foal.