The effect of insulin infusion on heart rate and systemic blood pressure in horses with equine metabolic syndrome.
Authors: Nostell K, Lindåse S, Edberg H, Bröjer J
Journal: Equine veterinary journal
Summary
# Editorial Summary Equine metabolic syndrome (EMS) is increasingly recognised as a systemic condition affecting multiple organ systems beyond glucose metabolism, yet cardiovascular responses in affected horses remain poorly characterised. Nostell and colleagues investigated whether horses with EMS display altered cardiovascular dynamics during hyperinsulinaemia by comparing 16 EMS-positive and 12 control horses using an oral sugar test for classification, followed by a euglycaemic hyperinsulinaemic clamp with blood pressure monitoring at baseline, 60, 120 and 180 minutes. EMS horses demonstrated elevated resting heart rate (35.6 versus 30.3 beats/min) and, critically, failed to show the normal blood pressure reduction observed in control horses during sustained insulin infusion—systolic, diastolic and mean arterial pressures remained static throughout the three-hour clamp period in EMS horses whilst declining progressively in controls. These findings suggest that insulin resistance at the vascular level represents a distinct pathophysiological feature of EMS, independent of resting hypertension, with potential implications for cardiovascular stress during work and metabolic challenge. Practitioners should consider cardiovascular load as an additional risk factor when managing EMS horses, particularly during exercise or periods of metabolic demand, though larger-scale studies are needed to establish clinical thresholds and long-term consequences.
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Practical Takeaways
- •Elevated resting heart rate may be a clinical indicator of EMS in horses and warrants further metabolic screening
- •EMS horses show blunted blood pressure responses to insulin that differ from metabolically normal horses, suggesting underlying cardiovascular dysfunction related to insulin resistance
- •Cardiovascular monitoring during metabolic testing may help identify compensatory mechanisms in EMS horses and could inform management strategies
Key Findings
- •EMS horses had significantly higher resting heart rate (35.6 ± 5.1 beats/min) compared to control horses (30.3 ± 3.5 beats/min)
- •Systolic, diastolic and mean arterial blood pressure did not differ between EMS and control groups at baseline
- •Control horses showed gradual blood pressure decline during euglycaemic hyperinsulinaemic clamp, while EMS horses showed no decline in any blood pressure parameters
- •EMS horses demonstrate altered cardiovascular response to insulin infusion despite normal baseline blood pressures