Cardiorespiratory effects of enoximone in anaesthetised colic horses.
Authors: Schauvliege S, Gozalo Marcilla M, Duchateau L, Martens A, Vlaminck L, Pille F, Declercq J, Levet T, Gasthuys F
Journal: Equine veterinary journal
Summary
# Editorial Summary: Cardiorespiratory effects of enoximone in anaesthetised colic horses Anaesthetised colic horses frequently develop hypotension requiring inotropic support, yet evidence for optimal pharmacological management remains limited. Schauvliege and colleagues conducted a randomised controlled trial in 48 mature colic horses, administering either enoximone (0.5 mg/kg) or saline ten minutes after surgical incision whilst maintaining isoflurane anaesthesia with lidocaine infusion and mechanical ventilation; they measured cardiac index, heart rate, systemic vascular resistance, stroke index and oxygen delivery index at baseline and regular intervals over 30 minutes. Within ten minutes of enoximone administration, cardiac index, heart rate and oxygen delivery index increased significantly (P ≤ 0.003), whilst systemic vascular resistance decreased (P = 0.0043), with these haemodynamic advantages persisting over the 30-minute observation window—though notably, the effect was more pronounced in large intestinal colic cases than other colic types. Despite enoximone's rapid onset and favourable profile, its cardiovascular benefits proved substantially shorter-lived than reported in healthy anaesthetised ponies, suggesting colic-related pathophysiology may limit its sustained efficacy. For practitioners administering intraoperative inotropic support in colic cases, enoximone represents a valid option for acute haemodynamic rescue, though expectations should be tempered regarding duration of effect and dosing intervals may require adjustment accordingly.
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Practical Takeaways
- •Enoximone can be considered as a short-term inotropic support for hypotensive colic horses during general anaesthesia, but effects last only 30 minutes or less, so repeated dosing or alternative support strategies may be necessary for longer procedures
- •Large intestine colic cases may respond more predictably to enoximone than other colic types, though all responses are time-limited
- •The shorter duration of enoximone action in colic horses versus healthy animals suggests disease state significantly affects drug efficacy; plan accordingly with backup haemodynamic support strategies
Key Findings
- •Enoximone significantly increased cardiac index (P=0.0010), heart rate (P=0.0033), and oxygen delivery index (P=0.0007) while reducing systemic vascular resistance (P=0.0043) at 10 minutes post-treatment compared to baseline
- •Cardiovascular effects of enoximone were significantly different from saline control during the first 30 minutes, with higher oxygen delivery index and heart rate maintained
- •Treatment response varied by colic type, with large intestine colic cases showing markedly clearer heart rate differences between enoximone and saline (interaction P=0.0076 and P=0.0038)
- •Enoximone's cardiovascular effects in colic horses were substantially shorter in duration than previously observed in healthy ponies