Echocardiographic effects of a medetomidine–vatinoxan combination for sedating dogs without previously diagnosed heart disease

Abstract

Objective: To evaluate sedative and echocardiographic effects of medetomidine–vatinoxan in healthy dogs undergoing elective diagnostic procedures. Study design: Prospective, within-subject clinical study. Animals: A group of 17 healthy client-owned dogs sedated for diagnostic procedures. Methods: Onset of sedation, sedation scores, heart rate and noninvasive arterial blood pressure (oscillometric method) were assessed at baseline (T0), and at 5, 10 and 15 minutes (T15) following intramuscular injection of a medetomidine (1 mg m−2) and vatinoxan (20 mg m−2) combination. Transthoracic echocardiography was performed at T0 and T15. Data are expressed as median (interquartile range) or mean ± standard deviation and analysed with a Wilcoxon signed rank test or paired t-test. Results: Sedation onset occurred at 4 (3–5) minutes with maximum sedation scores reached at 12 (10–15) minutes. Maximum sedation scores were 12 (11–12) out of 12, allowing echocardiographic examination with minimal manual restraint and venous catheterisation. Heart rate decreased from 128 ± 40 at T0 to 74 ± 24 beats minute−1 at T15 (p < 0.001) while noninvasive arterial blood pressures remained unchanged. Ejection fraction (71 ± 8% to 53 ± 11%) and fractional shortening (42 ± 7% to 32 ± 5%) decreased at T15 (p < 0.001, both). End-systolic volume (11.6 ± 8.6 to 15.8 ± 9.3 mL, p = 0.012) and left ventricle internal diameter at end-systole (2.0 ± 0.6 to 2.3 ± 0.5 cm; p = 0.001) increased. A decrease was also observed in early diastolic velocities (transmitral: 89.6 ± 16.4 to 63.7 ± 15.8 cm s−1, p < 0.001; annular: 9.5 ± 2.1 to 7.9 ± 2.0 cm s−1, p = 0.007). Isovolumic relaxation time increased after medetomidine–vatinoxan injection (67.0 ± 22.2 to 85.8 ± 18.7 ms, p = 0.002). Conclusions and clinical relevance: Intramuscular medetomidine–vatinoxan induced reliable sedation while inducing changes in baseline echocardiographic variables in healthy dogs