Bias, limits of agreement, and percent errors between acceleromyography and mechanomyography in anesthetized dogs

•Extubation of dogs receiving a non-depolarizing neuromuscular block agent requires recovery of neuromuscular function.•Mechanomyography (MMG) is considered to be the gold standard for neuromuscular monitoring, but it is cumbersome to set up.•Acceleromyography (AMG) is commonly used in dogs in a clinical setting.•There were no statistical differences between MMG and AMG in variables of interest relating to neuromuscular function.•However, limits of agreement between MMG and AMG were wide. This study compared measurements of neuromuscular function with mechanomyography (MMG) and acceleromyography (AMG) in nine anesthetized dogs receiving 0.1mg/kg vecuronium intravenously. Train-of-four (TOF) stimulation was applied to each ulnar nerve every 15s. The resulting amplitude of the first twitch (T1) and the TOF ratio were measured with both monitors. The baseline TOF ratio (prior to vecuronium), onset time (time of injection to T125% between monitors were identified for each dog. Bias, limits of agreement (LOA) and percentage error (PE) between methods were calculated from Bland–Altman plots for T1 and TOF ratio for the complete data set, and for TOF≥0.7 during recovery. There were no statistical differences in baseline TOF ratio, onset, recovery index, duration, AMG 0.7 and AMG 0.9. Individual errors>25% were evident in onset, recovery index, AMG 0.7 and AMG 0.9. Overall, T1 and TOF ratio had a small bias, wide LOA and PE>100%. Percent error was reduced to 30% when TOF≥0.7 was analyzed. Although there were no statistical differences between MMG and AMG in any variable of interest, individual discrepancies, wide LOA and high PE suggest that these monitors should not be used interchangeably for serial measurements on the same animals.