Aortic rupture is a rare, life threatening condition that occurs mainly in Friesian horses. In Friesians, the rupture will usually occur at the aortic arch near the ligamentum arteriosum, and will result in an aortopulmonary fistula.
Depending on the severity of the rupture, horses may be found dead or depending on the type of rupture, the horse might survive for a variable number of years but usually less than 5 years.
Vera, Lisse, et al Differences in cardiovascular physiology between Friesian horses and Warmblood horses European Veterinary Conference Voorjaarsdagen. 2019