The effects of detomidine, romifidine or acepromazine on echocardiographic measurements and cardiac function in normal horses.
OBJECTIVE
To evaluate by echo- and electrocardiography the cardiac effects of sedation with detomidine hydrochloride, romifidine hydrochloride or acepromazine maleate in horses.


METHODS
An experimental study using a cross-over design without randomization.


METHODS
Eight clinically normal Standardbred trotters.


METHODS
Echocardiographic examinations (two-dimensional, guided M-mode and colour Doppler) were recorded on five different days. Heart rate (HR) and standard limb lead electrocardiograms were also obtained. Subsequently, horses were sedated with detomidine (0.01 mg kg(-1)), romifidine (0.04 mg kg(-1)) or acepromazine (0.1 mg kg(-1)) administered intravenously and all examinations repeated.


RESULTS
Heart rate before treatment with the three drugs did not differ significantly (p = 0.98). Both detomidine and romifidine induced a significant decrease (p < 0.001) in HR during the first 25 minutes after sedation; while acepromazine had a varying effect on HR. For detomidine, there was a significant increase in LVIDd (left ventricular internal diameter in diastole; p = 0.034) and LVIDs (left ventricular internal diameter in systole; p < 0.001). In addition, a significant decrease was found in IVSs (the interventricular septum in systole; p < 0.001), LVFWs (the left ventricular free wall in systole; p = 0.002) and FS% (fractional shortening; p < 0.001). The frequency of pulmonary regurgitation was increased significantly (p < 0.001). Romifidine induced a significant increase in LVIDs (p < 0.001) and a significant decrease in IVSs (p < 0.001) and FS% (p = 0.002). Acepromazine had no significant effect upon any of the measured values.


CONCLUSIONS
and clinical relevance The results indicate that sedation of horses with detomidine and to a lesser extent romifidine at the doses given in this study has a significant effect on heart function, echocardiographic measurements of heart dimensions and the occurrence of valvular regurgitation. Although the clinical significance of these results may be minimal, the potential effects of sedative drugs should be taken into account when echocardiographic variables are interpreted in clinical cases.
Buhl
Rikke
R
Department of Large Animal Sciences, The Royal Veterinary and Agricultural University, Frederiksberg C, Denmark. rib@kvl.dk
Ersbøll
Annette K
AK
Larsen
Nanna H
NH
Eriksen
Lis
L
Koch
Jørgen
J
D000075:Acepromazine / Q000494:pharmacology*; D000818:Animals; D018592:Cross-Over Studies; D004452:Echocardiography / Q000187:drug effects / Q000662:veterinary*; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006349:Heart Valve Diseases; D006736:Horses / Q000502:physiology*; D006993:Hypnotics and Sedatives / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology*; D016276:Ventricular Function / Q000187:drug effects
D006993:Hypnotics and Sedatives; D007093:Imidazoles; D000075:Acepromazine; C041255:detomidine; C076257:romifidine