History: Horse, Friesian, female, 3.5 years
Diagnosis: Heart/Aorta: acute, focal, rupture of aortic arch with acute hemorrhages into the vessel wall and surrounding connective tissue
Description: A 4.5cm long transverse rupture was present within the aortic arch, approximately 7cm distal of the aortic valve near the Ligamentum arteriosum. Coagulated blood and circumferential perivascular hemorrhage were attached to the rupture. The pericardium was filled with 4.5 liters of mostly clotted blood (pericardial tamponade).
Comments: This Friesian mare died spontaneously. Necropsy findings are consistent with a pericardial tamponade due to rupture of the aortic arch. Aortic rupture appears more often in Friesian horses or breeding stallions but can appear in any breed, sex or age. Clinically horses show colic-like distress, pale mucous membranes, peripheral edema, increased rectal temperature, tachycardia, and jugular pulsation followed by sudden death. Depending on the scope and location (intra- versus extrapericardial) of the rupture survival time may vary. Several cases include a predisposing aortic aneurysm at the site of rupture. In Friesian horses the aortic rupture often occurs near the Ligamentum arteriosum and may therefore cause an aorto-pulmonary fistulation.
Picture by: Angele Breithaupt, Department of Veterinary Pathology, Freie Universität Berlin, Germany
Authored by: Hannah Pischon, Department of Veterinary Pathology, Freie Universität Berlin, Germany