Aortic rupture in the Friesian horse. A search for genetic background

Abstract

This project will be part of a larger research project that maps out the phenotypic (clinical) and genotypic appearance of aortic rupture and aorto-pulmonary fistulation within the Friesian breed. Our research group consists of 4 major partners: The Utrecht University, The Ghent University, The Wageningen University and Wolvega Equine Clinic. The prevalence of aortic rupture is estimated to be ± 2% within the Friesian breed, which is much higher than the incidence seen in warmblood horses. Unlike warmblood horses, Friesian horses can develop a chronic form of aortic rupture that most often is overlooked by the owner, leading to possible dangerous situations, such as acute death during exercise. Aortic rupture is always fatal. Some horses die instantly, others can walk around with this pathology for weeks to months. And even when a veterinarian suspects a patient of having an aorto-pulmonary fistulation, the diagnostic methods are limited. Ante mortem diagnosis is quite often a challenge because the aorta ruptures in Friesian horses occur at another location than that seen in warmblood horses. Post mortem diagnosis requires adaptation of specific standardized cardiac incision techniques during autopsy. This means that the person who performs the autopsy should suspect presence of aortic rupture before start of the autopsy procedure. It learns us that most probably quite some cases are and have been overlooked in the presence and the past. Over the course of a few years our research group has managed to pool 46 fully illustrated aortic ruptures subjected to complete protocolled autopsy and pre-mortem diagnosis. This has led to the publication of International peer reviewed articles about the disease and presentations at International conferences. In view of the difficulties to recognize and diagnose this pathology, it is important that a lot of clinicians have access to this information. Epidemiological check of the pedigree of all ruptured cases, going 5 generations backwards has learned us a lot about the way this pathology is inherited. It also has helped us to identify a proper population of Friesian horses that can function as control population for genetic studies. We are currently checking for relatedness between our population of aortic ruptures on one hand and the population of dwarfism and hydrocephaly in horses on the other hand. This project aims to identify the genomic regions upon which the genes are located that are responsible for aortic rupture and aorto-pulmonary fistulation in the Friesian horse, and Identify strategic regions of base pairs to develop a suitable genetic test that can be used by the studbook to identify carrier horses. This will help to give proper breeding advise, for example which combinations can be created in a safe way?