VetMedHindlimb surgery in dogs: does epidural morphine improve postoperative analgesia over systemic opioids alone? — POSSIBLE (the treatment made no difference to postoperative pain scores)
In dogs undergoing hindlimb surgery, does epidural morphine vs systemic opioids alone improve postoperative analgesia?
Shelf #523 · gate-verified and displayed under the developer's blinded-trial rule
POSSIBLE (the treatment made no difference to postoperative pain scores): In dogs undergoing hindlimb (stifle / pelvic-limb) surgery, epidural morphine combinations did not produce lower postoperative pain scores than systemic opioids alone in either direct randomised trial. In Lewis 2014 (randomized, blinded, prospective clinical trial, 48 dogs undergoing stifle surgery), no differences in pain score, sedation score, rescue analgesia requirement or time to first rescue analgesia were detected among a morphine–lidocaine–ketamine infusion, a lumbosacral epidural with morphine and ropivacaine, both combined, or only intramuscular premedication with morphine. In Hoelzler 2005 (prospective randomized trial, 56 dogs undergoing tibial plateau leveling osteotomy), pain indices also did not differ (visual analog scores P=.190, multifactorial pain scores P=.371, pressure nociceptive threshold P=.160), but time to first hydromorphone dose was longer for the epidural group than the systemic-only control group (P=.005) and more analgesic interventions were administered to control dogs than epidural dogs (P=.015) — that is, the epidural spared rescue opioid dosing while pain scores were held the same, rather than lowering the scores themselves. A third, very small study (Sibanda 2006, 12 dogs) is consistent on rescue use: postoperative morphine was required by 4 control dogs versus 1 extradural dog. Design class (a): randomisation and blinding are both established by a carded record — Lewis 2014 states 'Randomized, blinded, prospective clinical trial' in its own wording; the record does not specify who was blinded, and no more than that is claimed. The honest limits: every epidural arm is a combination (morphine with ropivacaine or with bupivacaine), not epidural morphine alone, so no effect can be attributed to morphine alone; all trials allowed systemic rescue opioids, which tends to equalise pain scores between groups; the populations are stifle / femoro-tibial surgery only; and follow-up is 24 hours. Drafted Nov 10, 2026 (VetMed build, topic #523); all figures from the abstract fetched and verified at drafting.
Lewis 2014: no differences in pain score, rescue analgesia or time to first rescue among epidural morphine, an opioid infusion, both, or intramuscular morphine alone in 48 dogs having stifle surgery
Randomized, blinded, prospective clinical trial (record's own wording: 'Randomized, blinded, prospective clinical trial'; publication type: Randomized Controlled Trial)
Who: Dogs: 48 client-owned dogs that underwent stifle joint surgery (tibial plateau leveling osteotomy) in a clinical setting, randomly assigned to receive a constant rate infusion of a combination of morphine, lidocaine and ketamine; a lumbosacral epidural with morphine and ropivacaine; both treatments; or only intramuscular premedication with morphine (the systemic-opioids-alone comparator). Cardiopulmonary indices and isoflurane requirement were recorded during anaesthesia; a validated sedation scoring system and the modified Glasgow composite measure pain score were used after surgery once the swallowing reflex returned and body temperature was at least 36.7°C (98.1°F), at 60-minute intervals for 4 hours then at 4-hour intervals for 24 hours; dogs with a postoperative pain score > 5 of 24 were given morphine as rescue analgesia.
Result: No differences in heart rate, respiratory rate, systolic arterial blood pressure, end-tidal Pco2, end-tidal isoflurane concentration or vaporizer setting were detected among groups. No differences in pain score, sedation score, rescue analgesia requirement, or time to first rescue analgesia after surgery were detected. The record's conclusion: all 4 analgesic protocols provided acceptable analgesia for 24 hours after stifle joint surgery.
Watch out: The epidural arm is morphine plus ropivacaine, not epidural morphine alone, so this trial cannot isolate morphine's contribution. Forty-eight dogs split across four groups leaves roughly 12 dogs per arm, so a null result may reflect limited power for modest differences. The record states the trial was blinded but the abstract does not say who was blinded. Follow-up is 24 hours only.
Lewis KA, Bednarski RM, Aarnes TK, Dyce J, Hubbell JA. Postoperative comparison of four perioperative analgesia protocols in dogs undergoing stifle joint surgery. J Am Vet Med Assoc. 2014;244(9):1041-6. PMID: 24739113. Registry ID: none in the record. MeSH: Amides/administration & dosage, therapeutic use* · Analgesia/methods, veterinary · Analgesics/administration & dosage, therapeutic use · Anesthetics, Local/administration & dosage, therapeutic use · Animals · Dog Diseases/prevention & control · Dogs · Female · Ketamine/administration & dosage, therapeutic use* · Lidocaine/administration & dosage, therapeutic use* · Male · Morphine/administration & dosage, therapeutic use* · Postoperative Pain/prevention & control, veterinary* · Ropivacaine · Stifle/surgery*
Hoelzler 2005: pain indices did not differ after TPLO (VAS P=.190), but epidural morphine–bupivacaine dogs needed their first hydromorphone later (P=.005) and fewer interventions than systemic-only controls (P=.015)
Prospective, randomized clinical trial (record's own wording: 'Prospective, randomized clinical trial'; publication type: Randomized Controlled Trial) — blinding not stated in the record
Who: Dogs: 56 healthy dogs with naturally occurring cranial cruciate ligament rupture undergoing tibial plateau leveling osteotomy in a clinical setting, premedicated with intravenous hydromorphone and acepromazine and randomly assigned to preoperative epidural injection with morphine and bupivacaine (Group E), pre- and postoperative intra-articular injections of bupivacaine (Group IA), or neither epidural nor intra-articular treatment (Group C, the systemic-only comparator). All dogs were administered hydromorphone (0.05 mg/kg IV) at extubation and as needed to maintain comfort postoperatively, were observed continuously for 24 hours, and discomfort was assessed using visual analog pain scores (VASs), multifactorial pain scores (MPSs) and response to a pressure nociceptive threshold (PNT) device; time to 1st dose and total doses of hydromorphone were recorded.
Result: No differences in measured indices of postoperative pain were observed between dogs of each treatment group: VAS (P=.190), MPS (P=.371) and PNT (P=.160). Time to 1st analgesic intervention was longer for Group E compared with Group C (P=.005) and longer for Group IA compared with Group C (P=.032); the E-versus-IA difference was not significant. More analgesic interventions were administered to dogs in Group C compared with dogs in Group E (P=.015). On average more hydromorphone was administered to Group C compared with Group IA (P=.072) and to Group IA compared with Group E (P=.168), but statistical significance was not reached for these total-dose data. The record's conclusion is that pain indices can be minimised in any protocol if dogs are continuously observed and appropriately supplemented with parenteral opioids, but the frequency of postoperative opioid dosing can be minimised by epidural or intra-articular injections.
Watch out: The control group is not opioid-free: every dog received systemic hydromorphone premedication, at extubation and as rescue, so the comparison is epidural added to systemic opioids versus systemic opioids alone — which is the shelf question, but it also means equal pain scores were achieved by giving the control group more rescue doses; the demonstrated advantage is rescue-sparing and later first rescue, not lower pain. The epidural is morphine combined with bupivacaine. The intra-articular arm does not answer this shelf's question and is not relied on. No blinding is stated in the record.
Hoelzler MG, Harvey RC, Lidbetter DA, Millis DL. Comparison of perioperative analgesic protocols for dogs undergoing tibial plateau leveling osteotomy. Vet Surg. 2005;34(4):337-44. PMID: 16212588. Registry ID: none in the record. MeSH: Analgesia/methods, veterinary* · Analgesics, Opioid/therapeutic use* · Anesthetics, Local/therapeutic use · Animals · Anterior Cruciate Ligament/surgery* · Anterior Cruciate Ligament Injuries · Bupivacaine · Dog Diseases/drug therapy* · Dogs · Injections, Epidural/methods, veterinary · Injections, Intra-Arterial/methods, veterinary · Injections, Intravenous/methods, veterinary · Morphine · Osteotomy/methods, veterinary · Pain Measurement/veterinary · Postoperative Pain/drug therapy, veterinary* · Perioperative Care/methods, veterinary* · Prospective Studies · Rupture/surgery, veterinary · Stifle/injuries, surgery · Treatment Outcome
Sibanda 2006: postoperative morphine was required by 4 of 6 control dogs versus 1 of 6 extradural bupivacaine–morphine dogs in a 12-dog femoro-tibial surgery study
Prospective clinical study (record's own wording); publication type: Randomized Controlled Trial — allocation method and blinding not described in the record's abstract
Who: Dogs: 12 client-owned dogs undergoing femoro-tibial joint surgery (repair of cruciate ligament rupture in ten, correction of luxating patella in two; body masses 12 to 45 kg) in a clinical setting. Six dogs received preoperative extradural bupivacaine (up to 1.5 mg kg(-1)) combined with morphine (0.1 mg kg(-1); ED group) and the other six received no extradural analgesia (C group). Cortisol, acute phase proteins and red and white blood cell variables were measured before and at various times after surgery; pain was also assessed at various times, and the number of postoperative morphine doses required and their time of administration were recorded for each animal.
Result: Cortisol levels in the ED group were significantly (p < 0.05) lower than those of the control group at the end of surgery. No statistically significant differences were found in acute phase proteins or red and white cell variables between groups. Four dogs in the control group and one in the ED group required postoperative morphine. The record reports no numerical between-group pain-score difference in its abstract. The record's conclusion is that pre-emptive extradural bupivacaine and morphine was effective in lowering the neuroendocrine stress response (cortisol) but had no effect on the inflammatory (acute phase) response.
Watch out: Only 12 dogs (6 per group), and the study's primary focus is the stress response — cortisol is a surrogate, not a pain score, and the abstract gives no numerical pain-score comparison, so this card supports only the rescue-morphine count (4 versus 1), which is too small to carry a claim on its own. The extradural treatment is again a bupivacaine–morphine combination.
Sibanda S, Hughes JM, Pawson PE, Kelly G, Bellenger CR. The effects of preoperative extradural bupivacaine and morphine on the stress response in dogs undergoing femoro-tibial joint surgery. Vet Anaesth Analg. 2006;33(4):246-57. PMID: 16764590. Registry ID: none in the record. MeSH: Analgesics, Opioid/administration & dosage* · Anesthesia, Spinal/veterinary · Anesthetics, Local/administration & dosage* · Animals · Anterior Cruciate Ligament/surgery · Anterior Cruciate Ligament Injuries · Bupivacaine/administration & dosage* · Dogs/injuries, physiology*, surgery · Drug Therapy, Combination · Female · Hydrocortisone/blood · Injections, Epidural/veterinary · Knee Injuries/surgery, veterinary · Male · Morphine/administration & dosage* · Pain Measurement/veterinary · Postoperative Pain/prevention & control, veterinary* · Preoperative Care/veterinary · Prospective Studies · Stifle/injuries, surgery · Treatment Outcome
Synthesis: epidural morphine combinations did not lower pain scores versus systemic opioids alone, but one trial showed later and less frequent rescue opioid use
Synthesis
Who: Synthesis of the cards above: Lewis 2014 (48 dogs, stifle surgery, randomized blinded trial with an intramuscular-morphine-only arm), Hoelzler 2005 (56 dogs, TPLO, prospective randomized trial with a systemic-only control arm) and Sibanda 2006 (12 dogs, femoro-tibial surgery, prospective study). All epidural treatments were morphine combined with a local anaesthetic (ropivacaine or bupivacaine), and systemic rescue opioids were available in every trial.
Result: (1) Pain scores: no difference in either direct trial — Lewis detected no differences in pain score, rescue requirement or time to first rescue among its four protocols, and Hoelzler found VAS P=.190, MPS P=.371 and PNT P=.160 across groups. (2) Rescue sparing: inconsistent — Hoelzler found time to first hydromorphone longer for epidural versus control (P=.005) and more interventions in control than epidural dogs (P=.015), and Sibanda's counts point the same way (4 versus 1 dogs needing postoperative morphine), but Lewis detected no rescue difference at all. (3) No carded record tests epidural morphine alone (without a local anaesthetic) against systemic opioids alone.
Watch out: Epidural comparisons that do not answer this shelf's question were not carded: epidural bupivacaine with versus without added morphine or dexmedetomidine for pelvic orthopaedic surgery (PMID: 23742641) compares epidural mixtures with each other, not with systemic opioids alone, and epidural morphine versus saline placebo after stifle arthrotomy (PMID: 8560749) has a placebo, not a systemic-opioid, comparator — neither is re-carded or relied on here. Nothing in this pack addresses hindlimb procedures other than stifle / femoro-tibial surgery, epidural morphine without a local anaesthetic, or analgesia beyond 24 hours.
Synthesis of Lewis KA et al. PMID: 24739113; Hoelzler MG et al. PMID: 16212588; Sibanda S et al. PMID: 16764590. Registry IDs as on the individual cards.
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