Effects of sedation with acepromazine on echocardiographic measurements in eight healthy thoroughbred horses.
Authors: Menzies-Gow N J
Journal: The Veterinary record
Summary
# Editorial Summary: Acepromazine Sedation and Equine Cardiac Measurements Acepromazine is widely used in equine practice for sedation, yet its effects on cardiac structure have received limited scrutiny. Menzies-Gow assessed eight healthy thoroughbreds using echocardiography before and ten minutes after intravenous acepromazine administration (0.03 mg/kg), measuring multiple cardiac dimensions and functional parameters. Sedation produced statistically significant structural changes: both the pulmonary artery and aortic diameters increased at end-systole, the interventricular septum thickened measurably at both end-systole and end-diastole, and the left atrial diameter decreased significantly at end-diastole—though notably, cardiac function indices, heart rate variables and valvular regurgitation patterns remained unaffected. These morphological shifts likely reflect the drug's peripheral vasodilatory and sympathomimetic properties rather than primary myocardial dysfunction. For practitioners performing pre-operative or diagnostic echocardiography, awareness that acepromazine sedation produces transient but measurable changes in vessel and chamber calibration is important; comparison against unsedated baseline measurements or recognition of these drug-induced variations may be necessary to avoid misinterpreting structural findings as pathological.
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Practical Takeaways
- •Acepromazine sedation causes reversible changes in cardiac dimensions that should not be confused with pathological alterations when performing echocardiography in clinical practice
- •Standardize sedation protocols when comparing serial echocardiographic measurements in individual horses, as acepromazine alters several structural parameters
- •Normal cardiac function and valve competency are maintained despite dimensional changes, so these echocardiographic alterations do not indicate clinical concern
Key Findings
- •Acepromazine (0.03 mg/kg IV) caused significant increases in pulmonary artery and aortic diameters at end-systole (P<0.025)
- •Interventricular septum thickness increased significantly at both end-systole and end-diastole with sedation (P<0.025)
- •Left atrial diameter at end-diastole decreased significantly with acepromazine (P<0.001)
- •Cardiac function indices and valvular regurgitation were unaffected by sedation