Acepromazine, Detomidine and Morphine: "The wooden horse". Evaluation of standing sedation protocols in equine patients undergoing bone scintigraphy

During equine scintigraphy examinations, motion artifacts are the main cause of retakes. Aim of the study is to evaluate two sedative protocols in horses undergoing bone scintigraphy, focusing on immobility and sedation quality. Twenty-nine horses were enrolled in an observer blinded, randomized, prospective clinical pilot study. All received acepromazine 0.003 mg kg-1 IV followed 30 minutes later by detomidine 10 g kg-1 IV. Five minutes later, morphine (MOR) 0.25 mg kg-1 (n=17) or butorphanol (BTF) 0.01 mg kg-1 (n=12) was administered IV; adjunctive boluses of detomidine were administered to maintain appropriate sedation. HR, fr, temperature, and sedation score (Taylor P. et al. 2014) were assessed. Number of retakes needed to obtain excellent diagnostic image quality evaluated by the same radiologist were recorded. Data were analysed using Student’s t-test, Mann-Whitney test, where appropriate (p  0.05). No difference in HR between groups (p = 0.1); fr was higher in BTF group (p = 0.002). Total amount of detomidine used was not different between groups (p = 0.49). Sedation score was not significantly different between groups (p = 0.4). Number of retakes for each region investigated was greater in BTF group (p = 0.01). Ratio between total number of retakes and total scan acquisitions number for each group was 48% in MOR and 96 % in BTF. Both protocols seem to demonstrate same sedation quality but the protocol whit Morphine, achieves higher patient immobility. Further studies are needed to evaluate this protocol in other diagnostic imaging techniques that require standing sedation.