A comparison of dobutamine infusion to exercise as a cardiac stress test in healthy horses.

The research article explores a study on the effects of dobutamine infusion compared to treadmill exercise as cardiac stress tests on healthy horses. The research unveils that while dobutamine produced somewhat similar physical alterations as exercise, its potential to induce harmful arrhythmias or cause myocardial toxicity negates its use as a cardiac stress-inducing agent.

Methodology

• Fourteen healthy horses were involved in the research. They went through a maximum treadmill exercise and, separately, intravenous dobutamine infusion.
• The rate of dobutamine infusion was allowed maximally up to a rate of 50 micrograms/kg/min.
• Of the fourteen horses, ten were euthanized, allowing the researchers to conduct a gross and histopathological examination of the myocardial tissues.

Findings

• There were no significant differences found between the effects of dobutamine and exercise on the heart rate (chronotropic effects).
• However, dobutamine caused a more significant interventricular septal thickening during systole and larger diameters for left ventricles during diastole than exercise treatment.
• At moderate to high doses of dobutamine, horses showed temporary signs of restlessness and sweating.
• 11 out of 14 horses exhibited ventricular ectopy (abnormal heart rhythms), which were attributed to dobutamine’s arrhythmogenic properties and the increased vagal tone present at low doses of dobutamine.
• Clear myocardial lesions characteristic of catecholamine-related myocardial toxicity were observed in two out of the ten horses examined pathologically.

Conclusion

• While dobutamine does induce changes that are similar to those brought on by physical exercise, using high-dose dobutamine as a stressor for horses’ hearts is not recommended.
• The reason for this conclusion is dobutamine’s potential to prompt arrhythmias or cause myotoxicity, which harms the muscle tissue of the heart.