Effects of a Caudal Epidural Anesthesia Using Midazolam With or Without Lidocaine to Perform an Endometrial Biopsy in Mares

The aim of the study was to evaluate the effectiveness of midazolam in combination with lidocaine to induce caudal analgesia and cervical dilation to facilitate endometrial biopsy procedures. Eighteen mares undergoing endometrial biopsy were randomly allocated to three treatments groups that received epidural anesthesia (n = 6): 0.9% saline solution (SS) (6 mL, control group); midazolam maleate (MID) (0.05 mg/kg); and midazolam maleate (0.05 mg/kg) plus 2% lidocaine (MIDLID) (0.1 mg/kg). Systemic parameters, behavior, and motor blockade were measured at baseline and at 10, 30, and 60 minutes after treatments. A subjective score system was used to assess pain and cervical dilation during the reproductive procedures at the same time points. Satisfactory analgesia was recorded for both epidural midazolam treatment groups 8 ± 4 minutes postadministration of the drug; analgesia remained satisfactory until the end of the trial period (60 minutes, P > .05). All animals in the control group showed evident pain (P = .001) due to the analgesic tests and reproductive procedures. Cervical dilation (P = .0001) occurred 20 minutes after epidural injections for both treatment groups with midazolam, but this effect did not occur in the control treatment group. Systemic effects were not observed (P > .05) in baseline values or among treatment groups following caudal epidural administration of midazolam or midazolam/lidocaine treatments. Epidural analgesia using midazolam alone or the combination of midazolam and lidocaine may be a good alternative for painful reproductive and gynecologic procedures in mares.