Objectives: Our aims are to improve quality of [recovery from anesthesia] by maximizing analgesia through lumbosacral epidural anesthesia (LEA) and by minimizing common side effects of systemic analgesics such as sedation or nausea/inappetence. Our second aim is to find the lowest concentration of epidural ropivacaine that yields these results, so that motor block, a side effect of LEA, is also minimized, as lack of motor function can delay discharge.

Methods: In this randomized, blinded, controlled trial, 50 dogs undergoing elective ovariohysterectomy will be randomly assigned to receive either no LEA (control) or LEA with one of four concentrations (0, 0.06%, 0.125%, and 0.2%) of ropivacaine with buprenorphine 4μg/kg. Post-operatively, Glasgow pain scores, sedation scores, nausea/vomiting, and motor function will be recorded. If nausea or insufficient analgesia are found based on these assessments, an anti-nausea medication or rescue analgesia will be administered, respectively. Time of return to drinking, eating, urinating, and defecating will also be recorded.

Expected Outcomes: We expect that quality of recovery of dogs receiving LEA with a sufficient concentration of ropivacaine will surpass that of the control group [and require fewer rescue interventions]. We also expect to create a concentration-response curve for LEA and determine the minimum effective concentration of ropivacaine that prevents the need for systemic rescue analgesia.