title: Effectiveness of injection of local anesthetic into the retrobulbar space for postoperative analgesia following eye enucleation in dogs.
abstract: OBJECTIVE
  To assess the efficacy of a retrobulbar bupivacaine nerve block for postoperative analgesia following eye enucleation in dogs.
  
  
  METHODS
  Randomized controlled trial.
  
  
  METHODS
  22 dogs.
  
  
  METHODS
  Client-owned dogs admitted to the hospital for routine eye enucleation were enrolled with owner consent and randomly assigned to a treatment (bupivacaine hydrochloride) or control (saline [0.9% NaCl] solution) group. Baseline subjective pain scores were recorded. Anesthesia consisted of hydromorphone and midazolam preoperatively, thiopental or propofol for induction, and isoflurane in oxygen for maintenance. An inferior-temporal palpebral retrobulbar injection of either saline solution or bupivacaine was administered. Transpalpebral eye enucleation was performed. Pain scores were recorded at 0.25, 0.5, 1, 2, 4, 6, 8, and 24 hours after extubation (time 0) by observers masked to treatment groups. Dogs were given hydromorphone (0.2 mg/kg [0.09 mg/lb], IM or IV) as a rescue analgesic if the subjective pain score totaled >or= 9 (out of a maximum total score of 18) or >or= 3 in any 1 category.
  
  
  RESULTS
  9 of 11 control dogs required a rescue dose of hydromorphone, but only 2 of 11 dogs in the bupivacaine treatment group required rescue analgesia. Mean time to treatment failure (ie, administration of rescue analgesia following extubation) was 0.56 hours (95% confidence interval, 0.029 to 1.095 hours) for the 11 dogs that received hydromorphone.
  
  
  CONCLUSIONS
  Retrobulbar administration of bupivacaine in dogs in conjunction with traditional premedication prior to eye enucleation was an effective form of adjunctive analgesia and reduced the need for additional postoperative analgesics.
authors.affiliation: Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA.
authors.forename: Kathern E
authors.initials: KE
authors.lastname: Myrna
authors.forename: Ellison
authors.initials: E
authors.lastname: Bentley
authors.forename: Lesley J
authors.initials: LJ
authors.lastname: Smith
mesh_terms: D000698:Analgesia / Q000662:veterinary*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D002045:Bupivacaine / Q000008:administration & dosage* / Q000494:pharmacology*; D004283:Dog Diseases / Q000517:prevention & control / Q000601:surgery; D004285:Dogs; D015353:Eye Enucleation / Q000662:veterinary*; D005260:Female; D008297:Male; D010149:Postoperative Pain / Q000517:prevention & control / Q000662:veterinary*
chemical_list: D000779:Anesthetics, Local; D002045:Bupivacaine