Postmortem diagnosis of venous air embolism in a Wielkopolski horse

Nine days after a surgical intervention due to an injury of the left hind hoof capsule, a 9-y-old, 538-kg female Wielkopolski horse was found recumbent in its stall with an unplugged permanent intravenous catheter positioned in the left jugular vein. Despite immediate resuscitation attempts, the animal died within minutes. Suspecting venous air embolism, radiographic imaging and detailed postmortem examinations were performed. However, visualization of the heart by radiography was hindered by the animal's body mass and postmortem changes. The autopsy followed a modified Richter method, originally developed for diagnosing air embolism in humans. The horse was positioned in left lateral recumbency to allow in situ access to the atria and venous sinuses. Gas bubbles observed in the right atrium and ventricle confirmed venous air embolism as the cause of death. Venous air embolism is a rarely documented cause of death in veterinary pathology. We present here an autopsy protocol for diagnosis of venous air embolism in large animals, which is primarily a macroscopic diagnosis.