Postmortem diagnosis of venous air embolism in a Wielkopolski horse.

Overview

• This study reports a case of venous air embolism causing sudden death in a 9-year-old Wielkopolski horse following surgery and presents a detailed postmortem protocol adapted for diagnosing this condition in large animals.

Background

• The subject was a 9-year-old female Wielkopolski horse weighing 538 kg.
• The horse had undergone surgical treatment for an injury to the left hind hoof capsule.
• Nine days post-surgery, the horse was found recumbent with a permanent intravenous catheter unplugged in the left jugular vein.
• Despite immediate resuscitation efforts, the horse died within minutes.

Suspected Cause and Diagnostic Approach

• Venous air embolism was suspected as the cause of death due to the clinical circumstances indicating possible air entry into the venous system.
• Initial radiographic imaging was performed to detect air in the cardiovascular system.
• However, visualization of the heart via radiography was challenging due to:
• The large body mass of the horse.
• Postmortem changes that can obscure radiographic images.

Postmortem Examination Methodology

• An autopsy was conducted using a modified Richter method, a technique originally developed for diagnosing air embolism in humans.
• The horse was placed in left lateral recumbency to enable:
• In situ access to the atria of the heart.
• Exposure of venous sinuses for examination.
• During the autopsy, gas bubbles were observed in the right atrium and right ventricle.
• The presence of these gas bubbles confirmed the diagnosis of venous air embolism as the cause of death.

Significance and Contributions

• Venous air embolism is infrequently documented as a cause of death in veterinary pathology, making this case significant.
• The study provides a practical autopsy protocol tailored for large animals to improve diagnosis of venous air embolism.
• The emphasis is placed on macroscopic examination because venous air embolism diagnosis largely depends on identifying visible gas bubbles during necropsy.
• This protocol can aid veterinarians and pathologists in confirming causes of sudden death associated with intravenous catheterization or surgical interventions.

Concluding Remarks

• The report highlights the importance of meticulous postmortem examination when venous air embolism is suspected.
• Adaptation of human diagnostic techniques such as the modified Richter method is effective for large animal pathology.
• Early recognition and prevention during intravenous catheter management may reduce the risk of fatal air embolisms in horses and other large animals.