COMPARISON OF INTRAARTICULAR AND EPIDURAL MORPHINE FOR ANALGESIA FOLLOWING STIFLE ARTHROTOMY IN DOGS

We prospectively studied 18 dogs that presented for exploratory stifle arthrotomy, with or without meniscectomy, and lateral extracapsular s tabilization as a result of cranial cruciate ligament rupture. Dogs we re premedicated with acepromazine, induced with thiopental, and mainta ined with halothane in oxygen. Preoperatively, dogs were assigned to o ne of three groups. Group 1 (n = 6) received intra-articular morphine (0.1 mg/kg diluted in 1 mL/10 kg body weight of saline) and epidural s aline (1 mL/5 kg body weight saline plus the volume of saline represen ting 0.1 mg/kg of morphine). Group 2 (n = 6) received intra-articular saline (1 mL/10 kg body weight of saline plus the volume of saline rep resenting 0.1 mg/kg of morphine) and epidural saline (1 mL/5 kg body w eight saline plus the volume of saline representing 0.1 mg/kg of morph ine). Group 3 (n = 6) received intra-articular saline (1 mL/10 kg body weight of saline plus the volume of saline representing O.1 mg/kg of morphine) and epidural morphine (0.1 mg/kg of morphine diluted in 1 mL /5 kg body weight saline). The efficacy of each analgesia regimen was evaluated for 6 hours postoperatively with a pain score based on subje ctive and objective variables. Serum cortisol and blood glucose concen trations were measured. Butorphanol was used to provide analgesia as n eeded based on a predetermined maximum pain score. Supplemental analge sics were required postoperatively every 2 to 3 hours for 6 hours in a ll dogs that did not initially receive analgesics (group 2). Pain scor es were significantly lower in dogs administered morphine intra-articu larly (group 1) and epidurally (group 3) at 30 minutes and 30, 120, an d 360 minutes, respectively, compared with dogs that did not initially receive analgesics (group 2). One dog in group 1 and one dog in group 3 required supplemental analgesia with butorphanol. There was no diff erence between analgesia produced by intra-articular morphine compared with that of epidural morphine. Side effects after intra-articular or epidural morphine were not observed. Intra-articular administration o f morphine can produce effective analgesia in dogs comparable with tha t produced by epidural administration of morphine. (C) Copyright 1995 by The American College of Veterinary Surgeons