Aortopulmonary fistula in a Warmblood mare associated with an aortic aneurysm and supravalvular aortic stenosis.
Authors: Saey Veronique, Decloedt Annelies, Van Poucke Mario, Peelman Luc, van Loon Gunther, Vanderperren Katrien, Ducatelle Richard, Chiers Koen
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary A 13-year-old Warmblood mare presenting with colic and a prominent holosystolic murmur was found to have a complex cardiovascular pathology involving supravalvular aortic stenosis (SVAS), thoracic aortic aneurysm, pseudoaneurysm, and critically, an aortopulmonary fistula—an abnormal connection between the aorta and pulmonary artery. Echocardiographic imaging identified the anatomical defects ante mortem, whilst necropsy and histopathological examination revealed rupture of the thoracic aorta with chronic remodelling changes including fibrosis, elastin fragmentation, mucin deposition, and mineralisation, alongside lesions in the mid-abdominal aorta suggestive of systemic elastin arteriopathy. Despite these significant structural changes, genetic analysis failed to identify mutations in the elastin gene—the primary locus for SVAS in equines—indicating either a non-genetic aetiology or involvement of alternative genetic pathways. This case documents an exceptionally rare presentation of aortopulmonary fistulation in equines and underscores the diagnostic value of echocardiography in investigating unexplained cardiac murmurs alongside gastrointestinal signs; moreover, it highlights that elastin-related cardiovascular disease in horses may be genetically heterogeneous, warranting expanded molecular investigation when clinical and histological findings implicate elastin pathology without confirmatory genetic results.
Read the full abstract on PubMed
Practical Takeaways
- •A loud holosystolic cardiac murmur in a horse with acute colic warrants immediate echocardiographic evaluation to rule out life-threatening aortic pathology such as aneurysm or fistulation.
- •Supravalvular aortic stenosis can occur in association with aortic aneurysm and aortopulmonary fistula; these conditions may represent different manifestations of a systemic vascular disease.
- •Elastin arteriopathy may not always have an identifiable genetic basis in the elastin gene, suggesting other genetic or acquired mechanisms may contribute to aortic disease in horses.
Key Findings
- •A 13-year-old Warmblood mare presented with colic and a holosystolic murmur caused by a thoracic aortic aneurysm that ruptured and fistulated into the pulmonary artery.
- •Echocardiography identified supravalvular aortic stenosis, aortic pseudoaneurysm, periaortic hematoma, and aortopulmonary fistulation.
- •Histological examination revealed chronic lesions including fibrosis, mucin depositions, mineralizations, elastin fragmentation, and systemic elastin arteriopathy features.
- •Molecular analysis did not identify a variant in the elastin gene despite clinical and histological findings consistent with elastin arteriopathy.