Evaluation of echocardiographic parameters during increasing infusion rates of dobutamine in isofluorane-anesthetized horses.

Aim. to evaluate changes in echocardiographic parameters during increasing infusion rates of dobutamine in anesthetized horses and to compare our results with previous studies. Materials and Methods. Six Standardbred female horses were included. All the animals were anesthetized and infused with different rates of dobutamine. MAP, HR, and some echocardiographic measurements were recorded. Statistical analysis was applied. Results. At basal conditions, HR ranged was 32-42 bpm, MAP 39-63 mmHg. MAP increased significantly in a dose-dependent manner, while CPO, HR and CO increased significantly at the higher dosage. EF, LVDs and LVVols decreased significantly in a dose-dependent manner, while IVSs increased. Arrhythmias were diagnosed 5/6 horses. Discussion. The increase of MAP was in line with literature. The HR and MAP values at T0 are comparable to previous results obtained both in anesthetized and conscious horses, while after dobutamine infusion HR and MAP values are similar to those reported in anaesthetized horses. IVSs increased and LVDs decreased with the increment of dobutamine infusion rates. These findings suggest that dobutamine, even at low infusion rates, induces an enhancement in cardiac systolic function. The dose-dependent increase of IVSs and decrease of LVDs measurements are in line with those reported for dobutamine administered in conscious horses, but with lower values. The LVVols dose-dependent reduction is in line with others. The increment of CO might be due mainly to the enhanced HR than to the weak changes of SV. CPO increased from the 5 mcg/kg/min dosage in a dose-dependent manner, as reported by others