Comparison of the application of lidocaine, lidocaine-dexamethasone and lidocaine-epinephrine for caudal epidural anesthesia in cows

The aim of the present study was to determine whether the addition of dexamethasone (DEX) or epinephrine to lidocaine (LID) altered the characteristics of anesthesia and cardiorespiratory variables following caudal epidural application in cows. Twenty adult dairy cows were randomly assigned to receive one of the treatments of LID (0.2 mg/kg), DEX (8 mg), lidocaine-dexamethasone (LIDEX; 0.2 mg/kg and 8 mg, respectively) and lidocaine-epinephrine (LIDEP; 0.2 mg/kg and 5 mu g/ml, respectively) by epidural injection with the final volume of 0.018 ml/kg and 10 ml of solution as the upper limit. The time to the onset and duration of anesthesia as well as heart rate (HR), respiratory rate (f(R)) and rectal temperature (RT) were recorded. No local anesthetic effects were observed in DEX. The onset of anesthesia did not show significant differences among LID, LIDEX and LIDEP (P>0.05). The duration of anesthesia was significantly longer in LIDEX (152.4 +/- 25.8 min) as compared to LID (116.0 +/- 11.5 min). Although the duration of anesthesia in LIDEP (137.7 +/- 10.0 min) was longer in comparison to LID, the difference was not statistically significant. There was no significant difference regarding the onset and duration of anesthesia between LIDEX and LIDEP. HR, f(R) and RT did not show significant changes over time. Mild transient ataxia was observed in groups that received lidocaine-containing solutions. In conclusion, addition of DEX to LID, without altering the time to onset, produced more prolonged anesthesia than that of LID alone following caudal epidural application in cows.