Partial hemipelvectomy with rapid recovery of ambulation and long-lasting analgesia after intrathecal administration of low-dose hypobaric bupivacaine and morphine

Introduction: Aim of this study is to report the intrathecal use of an hypobaric anesthetic solution containing bupivacaine 0.18% and morphine to provide anesthesia of the surgical site during partial hemipelvectomy in a 9-year-old, neutered female, Golden Retriever dog, weighing 34 kg. Materials and methods: Under inhalational anesthesia, with the dog lying in lateral recumbency and the surgical side uppermost, 1.9 ml of a hypobaric solution containing 3.42mg of bupivacaine and 0.66mg of morphine were administered in the subarachnoid space at L5-6 level 30 minutes before surgery. Following the intrathecal injection the dog was maintained for 5 minutes in a 101 head-down position, then 3 minutes in a 101 head-up position, then in a 51 head-down position until end of surgery. During surgery, the isoflurane vaporizer settings ranged from 1.8 to 2.1%, using a fresh gas flow of 0.8Lmin1 and a circle breathing system. Ketamine (14mg IV) was administered 10 minutes before surgery, and then every 60 minutes. Results: Apart from a transient increase in heart and respiratory rates during resection of the sartorius muscle, which was treated with a temporary plasma Target Controlled Infusion (TCI) of fentanyl at 0.5 ng ml1, spinal anesthesia provided cardiovascular stability and excellent relaxation of the surgical site. Motor blockade or proprioceptive deficits were not apparent in the contra-lateral pelvic limb at recovery, 200 minutes after injection. Postoperatively, no rescue analgesia was required in the 48 hours following surgery. No side effects or complications of the drugs used, nor neurological sequelae of spinal puncture occurred before discharge. Conclusions: Intrathecal hypobaric bupivacaine and morphine provided good anesthesia, rapid recovery of ambulation and excellent long-lasting analgesia in a dog undergoing partial hemipelvectomy. Its use should be considered during unilateral major orthopedic surgeries of the pelvis and pelvic limb. Further studies are warranted to assess drugs and doses to be used.