Spinal cord degeneration following general anaesthesia in a Shire horse.

This research article discusses a case of spinal cord degeneration in a Shire horse following general anesthesia for surgical correction of an umbilical hernia. The horse displayed post-operative signs of physical distress, and despite additional diagnostic procedures and treatments, died after 18 hours. A post-mortem analysis revealed significant lesions in the lumbosacral spinal cord, suggesting an incident of ischeamic myelopathy possibly connected with the anesthetic procedure.

Introduction

• The research article begins by providing background on the known complications related to general anesthesia in horses, which are mostly due to the species’ size and temperament, as well as certain central nervous system issues.
• The authors acknowledge previous research that has reported instances of spinal cord infarction during general anesthesia, however, emphasize that these are not commonly included in lists of potential complications from equine anesthesia.

Case History

• A detailed case study is given for an eight-month-old Shire filly that underwent surgery to repair an umbilical hernia. This surgery was performed under general anesthesia, with a detailed description of the specific medications and procedures used.
• Post-operatively, the horse showed signs of distress such as a significantly increased heart rate, difficulty standing, and signs of abdominal pain. Despite attempts to address these symptoms, the horse’s condition did not improve.
• A subsequent laparotomy revealed no obvious intestinal damage or adhesions, potentially ruling out issues related to the initial surgery as a cause of distress.

Necropsy Analysis

• Post-mortem analysis of the horse revealed significant lesions in the low lumbosacral spinal cord, suggesting an instance of ischaemic myelopathy, characterized by chromatolysis, pyknosis, karyolysis and axonal swelling.
• The timing of this lesion was also found to be consistent with the initial administration of general anesthesia, leading the authors to speculate that it may have been related.

Discussion

• The discussion emphasises the rarity of spinal cord damage or haemorrhage post general anaesthesia in horses, with only three cases previously reported.
• Common factors across all four cases are highlighted including young age of the horses, usage of the anaesthetic halothane, and the dorsal recumbency position utilized during surgery.
• The authors suggest that oxygenation of the lower spinal cord might have been compromised due to changes in blood flow that include arterial hypotension and stagnant hypoxia. Further evidence from physiological monitoring during anaesthesia is required to strengthen this hypothesis.