Maintenance of equine anaesthesia over the last 50 years: Controlled inhalation of volatile anaesthetics and pulmonary ventilation.
Authors: Mosing M, Senior J M
Journal: Equine veterinary journal
Summary
# Editorial Summary: Maintenance of Equine Anaesthesia and Pulmonary Ventilation Over five decades, inhalational anaesthesia practice in horses has evolved considerably as clinicians' understanding of volatile agents and respiratory physiology has deepened. Mosing and Senior's 2018 review examines this progression, tracing how halothane's initial popularity gave way to isoflurane and sevoflurane as awareness of halothane's hepatic and cardiovascular effects accumulated, demonstrating that drug choice remains responsive to emerging evidence rather than static dogma. The authors synthesise current knowledge of equine pulmonary anatomy and the pathophysiological consequences of anaesthesia on gas exchange and ventilation, highlighting why horses are particularly susceptible to hypoxaemia and atelectasis during general anaesthesia. Their critical appraisal of mechanical ventilation strategies reveals important gaps: whilst controlled ventilation is now standard practice, current modes may not optimally achieve the dual aims of maintaining oxygenation and minimising ventilation-induced lung injury. For equine anaesthetists and veterinary surgeons, this work underscores that whilst genuinely novel inhalational agents are unlikely to emerge imminently, refinements to ventilatory equipment and protocols remain achievable and necessary to improve perioperative outcomes and reduce post-anaesthetic complications in this high-risk species.
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Practical Takeaways
- •Equine practitioners should be aware that anaesthetic agent choice and ventilation strategies have evolved significantly over 50 years; current protocols with isoflurane or sevoflurane with optimised mechanical ventilation offer safer alternatives to older halothane-based regimens
- •Understanding the effects of anaesthesia on equine lung function helps explain common intraoperative complications and supports the use of appropriate ventilatory support during procedures
- •Future improvements in anaesthetic equipment and ventilator modes should be adopted when available, as further refinements in practice are likely to continue improving surgical outcomes
Key Findings
- •Halothane was initially widely adopted for equine anaesthesia but subsequent understanding of its effects led to replacement by isoflurane and sevoflurane
- •Better understanding of newer inhalation agents' pathophysiological effects continues to drive changes in equine anaesthetic practice
- •Advances in understanding equine lung anatomy and pathophysiology have clarified how anaesthesia impairs gas exchange and ventilation during procedures
- •Mechanical ventilation methods vary in their ability to achieve optimal anaesthetic management targets, with further developments in equipment and ventilator modes anticipated