Analgesic effect of epidural neostigmine and/or morphine after canine orthopedic surgery on a pelvic limb

Author(s)

Rodrigo Luiz Marucio

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2012-12-10

Examining board members

Denise Tabacchi Fantoni; Silvia Renata Gaido Cortopassi; Stélio Pacca Loureiro Luna; Flavio Massone; Irimar de Paula Posso

• Advisor: Denise Tabacchi Fantoni

Abstract

The epidural administration of cholinesterase inhibitor drug (nesotigmine) improves morphine analgesia for increased acetylcholine concentration in the cerebrospinal fluid. The aim of this study was to evaluate the possible analgesic effects of neostigmine and the possible potentiation of morphine analgesia in dogs undergoing orthopaedic pelvic limb surgery. Thirty healthy dogs, males or females, from several breeds were selected. They were sedated with meperidine (4 mg/kg IM). 30 minutes later, anestesia was induced with propofol (5 mg/kg IV) and anesthesia was maintained with isoflurane. An epidural catheter was inserted and local anaesthesia was performed with lidocaine 2% (5 mg/kg). At the end of surgical operation, the animals were randomly distributed into three groups of 10 animals each and received the analgesic treatment via epidural catheter using a factorial design: MOR group received 0.1 mg/kg morphine, while NEO group received 5 µg/kg neostigmine and MOR+NEO group received the combination of 0.1 mg/kg of morphine plus 5 µg/kg of neostigmine. In all cases, drug administration was completed with 0.4 ml of 0,9% NaCl. The study was characterized as a prospective, double-blind, randomized clinical trial. Parametric variables measured were heart rate (HR), respiratory rate (f), rectal temperature (T °C) and noninvasive estimation of systolic, diastolic and mean blood pressure (SBP, DBP, and MAP). Postoperative analgesia was evaluated on a visual analogue scale (VAS) and a descriptive numerical scale (DNS) at 1, 2, 3, 4, 6, 8, 10, 12, 16 and 24 hours after the end of the surgery. When the VAS and DNS were equal or greater than four, postoperative analgesia was supplied with morphine 0.2 mg/kg (IV), morphine 0.1 mg/kg (epidural) plus meloxicam 0.2 mg/kg (IV). There were no statistically significant differences in demographic and parametric variables between the groups. Supplemental analgesia were administered in 7 animals of NEO group, 4 animals of MOR group and 2 animals of MOR+NEO group. Animals of MOR+NEO group showed lower values in pain scores (VAS) than animals of NEO group at time 1 hour and animals of MOR group at time 4 hours. The incidence of side effects was similar between the three treatment groups. In short, neostigmine alone was not effective in treatment postoperative pain in dogs undergoing orthopaedic surgery. The analgesics effects of neostigmine plus morphine showed benefits without increasing the incidence of adverses events commonly observed when compared to the use of morphine alone. (AU)