title: Evaluation of analgesic and physiologic effects of epidural morphine administered at a thoracic or lumbar level in dogs undergoing thoracotomy.
abstract: OBJECTIVE
  To evaluate the analgesic and physiological effects of epidural morphine administered at the sixth and seventh lumbar or the fifth and sixth thoracic vertebrae in dogs undergoing thoracotomy.
  
  
  METHODS
  Prospective, randomized, blinded trial.
  
  
  METHODS
  Fourteen mixed-breed dogs, weighing 8.6 ± 1.4 kg.
  
  
  METHODS
  The animals received acepromazine (0.1 mg kg⁻¹) IM and anesthesia was induced with propofol (4 mg kg)⁻¹ IV. The lumbosacral space was punctured and an epidural catheter was inserted up to the region between the sixth and seventh lumbar vertebrae (L, n = 6) or up to the fifth or sixth intercostal space (T, n = 8). The dogs were allowed to recover and after radiographic confirmation of correct catheter position, anesthesia was reinduced with propofol IV and maintained with 1.7% isoflurane. Following stabilization of monitored parameters, animals received morphine (0.1 mg kg⁻¹) diluted in 0.9% NaCl to a final volume of 0.25 mL kg⁻¹ via the epidural catheter, and after 40 minutes, thoracotomy was initiated. Heart rate and rhythm, systolic, mean and diastolic arterial pressures, respiratory rate, arterial hemoglobin oxygen saturation, partial pressure of expired CO₂ and body temperature were measured immediately before the epidural administration of morphine (0 minute) and every 10 minutes during the anesthetic period. The Melbourne pain scale and the visual analog scale were used to assess postoperative pain. The evaluation began 3 hours after the epidural administration of morphine and occurred each hour until rescue analgesia.
  
  
  RESULTS
  There were no important variations in the physiological parameters during the anesthetic period. The post-operative analgesic period differed between the groups, being longer in T (9.9 01.6 hours) compared with L (5.8 ± 0.8 hours).
  
  
  CONCLUSIONS
  The use of morphine, at a volume of 0.25 mL kg 0.1, administered epidurally over the thoracic vertebrae provided longer lasting analgesia than when deposited over the lumbar vertebrae.
authors.forename: Adriano B
authors.initials: AB
authors.lastname: Carregaro
authors.forename: Gabrielle C
authors.initials: GC
authors.lastname: Freitas
authors.forename: Carlize
authors.initials: C
authors.lastname: Lopes
authors.forename: Rafael
authors.initials: R
authors.lastname: Lukarsewski
authors.forename: Fernanda S
authors.initials: FS
authors.lastname: Tamiozzo
authors.forename: Rogério R
authors.initials: RR
authors.lastname: Santos
mesh_terms: D000698:Analgesia / Q000379:methods / Q000662:veterinary*; D015360:Analgesia, Epidural / Q000662:veterinary*; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D004285:Dogs; D007432:Intraoperative Period; D009020:Morphine / Q000008:administration & dosage / Q000494:pharmacology*; D013908:Thoracotomy / Q000662:veterinary*
chemical_list: D000701:Analgesics, Opioid; D009020:Morphine