Traumatic arterio-venous fistula of the large cervical blood vessels in a horse

Abstract

An arteriovenous fistula is an abnormal connection or passageway between an artery and a vein. It may be congenital or acquired due to pathologic process, such as trauma or erosion of an arterial aneurysm. In the following case report the diagnosis and the angio-surgical therapy of an traumatically caused arterio-venous shunt is described. A 13 years old Arabian-Trakehner gelding developed a whizzing swelling of hand's size at the left neck after a trauma. Doppler sonography revealed an arterio-venous fistula with a shunt between the Arteria carotis communis and the Vena jugularis externa. The shunt related turbulences of the arterial and venous blood circulation were investigated intraoperatively by angiography and blood-gas analysis. The arteriovenous fistula was separated and the blood vessels were reconstructed during an unilateral interruption of the blood stream to the brain for 30 minutes. In addition, a biopsy of the shunt area was taken. Sonographic follow-up examinations were carried out over a period of 4 months. The surgical wound healed without complications. Phenprocoumon (Marcumar®, Roche, Grenzach-Wyhlen) was administered as anticoagulant treatment for 3 months during regular check of the coagulant status. The final sonographic examination confirmed a non-interfered arterio-veneous haemodynamic. The biopsy of the shunt area was histologically characterized by collagen and fibroblast rich, poorly vascularized connective tissue. Additionally, a lympho-plasmacellular infiltration and single neutrophilic infiltrates were seen. The horse achieved its original performance level 4 months after surgery. The Doppler sonography is a suitable technique for detecting an arterio-venous fistula between the Arteria carotis communis and the Vena jugularis externa in horses. This so far firstly reported type of shunt should be considered in the differential diagnosis of traumatically caused diseases of the large vessels in the jugular furrow of horses. The risky surgical repair of the affected vessels in close neighbourhood of the vagus nerve can be successfully managed in an interdisciplinary approach.