Echocardiographic and clinical effects of two sedative doses of Dexmedetomidine in healthy horses

The effects of dexmedetomidine (DEX), as a sedative drug, on echocardiographic measurements have been investigated in many species but not in horses. Therefore, this study aimed to evaluate the echocardiographic and clinical effects of two sedative doses of DEX in healthy horses. Six female crossbred horses weighted 250-330 kg underwent echocardiography before and after sedation by intravenous administration of a low dose of 3.5 μg/kg (LD) and a high dose of 7 μg/kg (HD) of DEX. A significant increase (p≤ 0.05) was observed in the diameters of the pulmonary artery and the left atrium measured at end-systole after HD treatment, as well as the aortic valve diameter measured at end-systole after LD and HD treatments. Furthermore, left and right ventricular internal diameter measured at end-systole increased significantly after LD and HD treatments. The mean and maximum values of pulmonary velocity and pulmonary pressure gradient were significantly decreased after LD and HD treatments. However, sedation did not affect the remaining cardiac dimensions, the various measures of cardiac function, or the presence and intensity of valvular regurgitation. This study showed that two sedative levels of DEX has an identical effect on most echocardiographic parameters, and like other alpha-2 agonists, DEX has an effect on echocardiographic parameters.