Comparison of topical lidocaine/prilocaine anesthetic cream and local infiltration of 2% lidocaine for episioplasty in mares

Local anesthesia and tissue inflammation associated with lidocaine infiltration and lidocaine/prilocaine topical anesthetic cream for episioplasty in mares were compared. Twenty-two mares were randomly assigned to lidocaine or lidocaine/prilocaine topical anesthetic cream treatment groups. Perineum and vulva were cleaned, 8-12 g (approximately 1 g/cm per side of vulva) of topical anesthetic cream was applied, and the area was covered by plastic wrap 30 min prior to beginning procedure. Alternately, lidocaine was injected (1 mL) every centimeter just prior to the procedure. Episioplasty was conducted using standard methods, but employing simple interrupted sutures. Horses were not sedated and use of a twitch was recorded. Four millimeter punch biopsies were harvested 1, 3, and 10 days following episioplasty and scored for degree of inflammation by a blinded pathologist. Clinical inflammation scores were assigned when biopsies were obtained. Seven of 11 horses receiving lidocaine infiltration required twitching, but none of the horses that received the anesthetic cream required twitching. Six of 11 and seven of 11 of the lidocaine and anesthetic cream groups, respectively, required twitching for episioplasty. Except for the clinical scores on day 3, no statistical differences for clinical and histopathologic scores between samples from the two treatment groups for a given day were identified. Use of lidocaine/prilocaine topical anesthetic cream was as effective as lidocaine infiltration in providing local anesthesia when performing episioplasty in mares. Its use decreased the need for twitching horses as well as the risk of deformation of the labia caused by lidocaine infiltration.