Suspected severe post‐anaesthetic myopathy or myelopathy in a Clydesdale horse resulting in euthanasia

Abstract

This case report describes suspected myopathy or myelopathy in a 5-year-old Clydesdale gelding following general anaesthesia for sarcoid removal. The lowest mean arterial pressure was 67 mmHg. Hyperlactataemia and tachycardia were observed during anaesthesia prompting abortion of surgery. The horse was unable to stand with assistance from a specialised sling. Azotaemia and hyperkalaemia developed in recovery and worsened despite therapeutic interventions. Euthanasia was performed given the grave prognosis. Postmortem examination was not carried out but could have provided a definitive diagnosis. Specific factors have been identified in the prevention of post-anaesthetic myopathy, including maintenance of adequate tissue perfusion and oxygenation and careful positioning. Potential improvements in the anaesthetic management of this case in relation to these factors are discussed.

Presumptive generalised post‐anaesthetic myopathy in a sevoflurane‐anaesthetised obese pony

“…According to the oxygen content equation, 19 the CaO 2 was 12.645 mL O 2 per 100 mL blood. This is lower than what has been estimated by Hubbell et al, 20 who stated 18 mL O 2 per 100 mL blood as the normal CaO 2 of horses on a FiO 2 of 95%, as used by Lloyd et al 21 This horse received a FiO 2 of 70% and the associated expected CaO 2 should have been around 13.25 mL O 2 per 100 mL blood, slightly higher than the observed value. Even if this lower CaO 2 might have decreased the global delivery of oxygen (DO 2 ), it is unlikely that this slight decrease of CaO 2 in the absence of hypotension contributed to the occurrence of PAM.…”