This study aimed to evaluate the relationship between the serum concentrations of lidocaine/monoethylglycinexylidide (MEGX) and their effects on several systems in horses. Five healthy,conscious horses received a two-hour placebo intravenous infusion followed by a two-hour lidocaineinfusion (bolus of 1.3 mg/kg over ten minutes followed by a continuous rate infusion of0.05 mg/kg/min). Lidocaine and MEGX serum concentrations were sampled every ten to fifteenminutes during the experiment, and the presence of muscle fasciculations and loss of balance aswell as the respiratory, digestive and cardiovascular systems of the five horses were evaluated bymeans of different non-invasive methods. During the lidocaine infusion, the mean (± SD) lidocaineand MEGX concentrations were respectively 768.88 ± 93.32ng/ml and 163.08 ± 108.98 ng/ml. Theinfusion of lidocaine significantly influenced the presence of fasciculations, caused a statisticallybut non-clinically significant decrease of systolic and diastolic blood pressures, which were bothcorrelated with lidocaine and MEGX serum concentrations, and it increased the duodenal contractionsfrequency, which was correlated with the serum lidocaine concentration. In this study,mild hypotensive and prokinetic effects of short-term lidocaine infusion were observed.