Heart rate and heart rate variability of dairy cows with or without local anesthesia

Heart rate variability analysis provides valuable insights into autonomic nervous system function but remains minimally explored in veterinary anesthesiology, particularly regarding its relationship with low-dose caudal epidural anesthesia in cattle. This study employed a crossover design to determine whether epidural lidocaine administration (4 mL of 2% solution) affects cardiac autonomic regulation compared with physiological saline in 8 healthy Holstein-Friesian dairy cows. Interbeat intervals were measured at baseline and for 240 min following epidural injection and cardiac autonomic activity-related parameters of heart rate variability (heart rate, root mean square of successive differences, high-frequency component, and ratio of low-frequency and high-frequency components) were calculated. Area under the curve for the first 240 min after the treatment and time to return to baseline were used to evaluate overall treatment effects on cardiac autonomic activity. Results revealed no differences in the area under the curve values for any parameters of heart rate variability between lidocaine and saline epidural interventions throughout the observation period, with comparable recovery times to baseline values between treatments. These findings suggest that sacrococcygeal epidural anesthesia did not detectably affect cardiac autonomic regulation in dairy cows under the conditions of this study.