Effect of intraperitoneal or incisional bupivacaine on pain and the analgesic requirement after ovariohysterectomy in dogs

ObjectiveTo compare the effect of intraperitoneal (IP) or incisional (INC) bupivacaine on pain and the analgesic requirement after ovariohysterectomy in dogs.Study designProspective, randomized clinical study.AnimalsThirty female dogs undergoing ovariohysterectomy (OHE).MethodsDogs admitted for elective OHE were anesthetized with acepromazine, butorphanol, thiopental and halothane. Animals were randomly assigned to one of three groups (n = 10 per group). The treatments consisted of preincisional infiltration with saline solution (NaCl 0.9%) or bupivacaine with epinephrine and/or IP administration of the same solutions, as follows: INC and IP 0.9% NaCl (control group); INC 0.9% NaCl and IP bupivacaine (5 mg kg^?1, IP group); INC bupivacaine (1 mg kg^?1) and IP 0.9% NaCl (INC group). Postoperative pain was evaluated by a blinded observer for 24 hours after extubation by means of a visual analog scale (VAS) and a numeric rating scale (NRS). Rescue analgesia (morphine, 0.5 mg kg^?1, IM) was administered if the VAS was >5/10 or the NRS >10/29.ResultsAt 1 hour after anesthesia, VAS pain scores were [medians (interquartile range)]: 6.4 (3.1–7.9), 0.3 (0.0–2.6) and 0.0 (0.0–7.0) in control, IP and INC groups, respectively. VAS pain scores were lower in the IP compared to the control group. Over the first 24 hours, rescue analgesia was administered to 7/10, 5/10 and 3/10 dogs of the control, INC and IP groups, respectively. Total number of dogs given rescue analgesia over the first 24 hours did not differ significantly among groups.Conclusions and clinical relevanceIntraperitoneal bupivacaine resulted in lower pain scores during the first hour of the postoperative period and there was a trend towards a decreased need for rescue analgesia after OHE in dogs.     

Comparison of intraperitoneal ropivacaine and ropivacaine–dexmedetomidine for postoperative analgesia in cats undergoing ovariohysterectomy

ObjectiveTo investigate the intraperitoneal (IP) administration of ropivacaine or ropivacaine–dexmedetomidine for postoperative analgesia in cats undergoing ovariohysterectomy.Study designProspective, randomized, blinded, positively controlled clinical study.AnimalsA total of 45 client-owned cats were enrolled.MethodsThe cats were administered intramuscular (IM) meperidine (6 mg kg⁻¹) and acepromazine (0.05 mg kg⁻¹). Anesthesia was induced with propofol and maintained with isoflurane. Meloxicam (0.2 mg kg⁻¹) was administered subcutaneously in all cats after intubation. After the abdominal incision, the cats were administered one of three treatments (15 cats in each treatment): IP instillation of 0.9% saline solution (group Control), 0.25% ropivacaine (1 mg kg⁻¹, group ROP) or ropivacaine and dexmedetomidine (4 μg kg⁻¹, group ROP–DEX). During anesthesia, heart rate (HR), electrocardiography, noninvasive systolic arterial pressure (SAP) and respiratory variables were monitored. Sedation and pain were assessed preoperatively and at various time points up to 24 hours after extubation using sedation scoring, an interactive visual analog scale, the UNESP-Botucatu multidimensional composite pain scale (MCPS) and mechanical nociceptive thresholds (MNT; von Frey anesthesiometer). Rescue analgesia (morphine, 0.1 mg kg⁻¹) IM was administered if the MCPS ≥6. Data were analyzed using the chi-square test, Tukey test, Kruskal–Wallis test and Friedman test (p < 0.05).ResultsHR was significantly lower in ROP–DEX compared with Control (p = 0.002). The pain scores, MNT, sedation scores and the postoperative rescue analgesia did not differ statistically among groups.Conclusions and clinical relevanceAs part of a multimodal pain therapy, IP ropivacaine–dexmedetomidine was associated with decreased HR intraoperatively; however, SAP remained within normal limits. Using the stated anesthetic protocol, neither IP ropivacaine nor ropivacaine–dexmedetomidine significantly improved analgesia compared with IP saline in cats undergoing ovariohysterectomy.     

Effects of perioperative saphenous and sciatic nerve blocks,lumbosacral epidural or morphine–lidocaine–ketamine infusion on postoperative pain and sedation in dogs undergoing tibial plateau leveling osteotomy

ObjectiveTo compare the quality of postoperative analgesia and sedation after preoperative saphenous and sciatic nerve blockade, preoperative lumbosacral epidural injection and perioperative intravenous (IV) morphine, lidocaine and ketamine infusions in dogs undergoing stifle arthroscopy and tibial plateau leveling osteotomy (TPLO) under general anesthesia.Study designProspective, blinded, randomized, clinical comparison study.AnimalsA total of 45 dogs weighing 33.9 (15.9–56.7) kg and aged 5.2 (1.0–12.0) years, mean (range), undergoing elective unilateral TPLO for spontaneous cranial cruciate ligament rupture.MethodsClient-owned dogs were enrolled. Dogs were randomly assigned to one of three groups: group MLK, perioperative IV morphine, lidocaine and ketamine infusion; group EPID, lumbosacral epidural with ropivacaine and morphine; or group SSNB, saphenous and sciatic nerve blockade with ropivacaine. Routine stifle arthroscopy followed by TPLO surgery was performed. Sedation and pain scores were assessed at 0, 2, 4, 8 and 24 hours following extubation. Rescue analgesia was administered as prescribed by Glasgow composite pain score–short form score >5.ResultsSedation scores for MLK were higher than EPID and SSNB. Pain scores for SSNB were lower than those for EPID and MLK. No significant differences were found in anesthesia duration or surgery duration among groups. No dogs required rescue analgesia.Conclusions and clinical relevanceAlthough analgesia was adequate in all groups, the best combination of analgesia without increased sedation was recorded for SSNB.     

Effects of tramadol alone,in combination with meloxicam or dipyrone,on postoperative pain and the analgesic requirement in dogs undergoing unilateral mastectomy with or without ovariohysterectomy

ObjectiveTo compare the effects of tramadol alone, or in combination with dipyrone or meloxicam, on postoperative pain and analgesia requirement after unilateral mastectomy with or without ovariohysterectomy in dogs.Study designProspective, randomized, clinical study.AnimalsTwenty seven bitches undergoing unilateral mastectomy with or without ovariohysterectomy.MethodsAnesthesia was induced with propofol and maintained with isoflurane and a constant rate infusion of morphine. Before the end of surgery, dogs were randomly assigned to receive intravenous tramadol alone (3 mg kg^?1, group T), combined with dipyrone (30 mg kg^?1, group TD) or meloxicam (0.2 mg kg^?1, group TM). Dogs received additional doses of tramadol (groups T and TM) or tramadol with dipyrone (group TD) at 8 and 16 hours after extubation. Postoperative pain was assessed by a blinded observer before anesthesia (baseline) and at 1, 2, 3, 4, 6, 8, 12, 16 and 24 hours after extubation using a visual analog scale (VAS) and a modified Glasgow scale. Rescue analgesia (morphine, 0.5 mg kg^?1) was administered if the Glasgow pain score was >3.5.ResultsThere were no significant differences among groups in pain scores evaluated by the VAS or the Glasgow scale. In groups T, TD and TM, pain scores were significantly higher than at baseline for 6, 8 and 2 hours, respectively. Rescue analgesia was administered to 3/9, 2/9 and 1/9 dogs in groups T, TD and TM, respectively (p > 0.05) [Correction added on 15 August 2013, after first online publication: ‘T, TM and TD’ was changed to ‘T, TD and TM’.].Conclusions and clinical relevanceUnder the conditions of this study, tramadol alone or in combination with dypyrone or meloxicam provided effective analgesia for 24 hours in most dogs after unilateral mastectomy with or without ovariohysterectomy. Further evaluation of combination therapies is needed in larger groups of dogs.     

Preperitoneal ropivacaine infusion versus epidural ropivacaine–morphine for postoperative analgesia in dogs undergoing ovariohysterectomy: a randomized clinical trial

ObjectiveTo assess the effect of continuous wound infusion (CWI) with preperitoneal ropivacaine on postoperative analgesia and compare it with the epidural administration of ropivacaine and morphine in bitches undergoing ovariohysterectomy.Study designA parallel, randomized, clinical, prospective and nonblinded study.AnimalsA group of 38 Greyhound bitches.MethodsIn the catheter group (CathG), CWI with ropivacaine 1% (1 mg kg^–1 + 0.8 mg kg^–1 hour^–1) was applied to the preperitoneal space over the surgical incision. In the epidural group (EpiG), ropivacaine 0.5% (1.3 mg kg^–1) and morphine (0.1 mg kg^–1) were epidurally administered. Occipital-coccygeal length was used to calculate the volume for the epidural. Pain was scored using a dynamic interactive visual analogue scale (DIVAS) and Glasgow composite measure pain scale–short form (CMPS-SF) before anaesthesia and at 2, 4, 6, 18, 21 and 24 hours after extubation. Incisional sensitivity using a dynamometer (MWTs-incision) was evaluated simultaneously. Plasma ropivacaine and cortisol concentrations, degree of sedation, motor blockade and response to interdigital clamping were measured or assessed. A two-way mixed analysis of variance and a Mann–Whitney U test were used to analyse data; p < 0.05.ResultsNo differences were detected in the DIVAS (p = 0.301), CMPS-SF (p = 0.600) scores, MWTs-incision measurements (p = 0.257) and cortisol values (p = 0.878) between the groups. Rescue analgesia was required in two dogs, one in each group, at 2 hours. Sedation, motor blockade and negative response to interdigital clamping were detected in EpiG at 2, 4 and 6 hours. Mean plasma ropivacaine values were higher in CathG (0.475 ± 0.164 ng mL^–1) than in EpiG (0.184 ± 0.213 ng mL^–1; p = 0.001).Conclusion and clinical relevanceCompared with epidural ropivacaine and morphine, CWI with preperitoneal ropivacaine is an effective analgesic technique for postoperative pain management in bitches undergoing ovariohysterectomy without motor blockade.     

Comparison of intraperitoneal ropivacaine and bupivacaine for postoperative analgesia in dogs undergoing ovariohysterectomy

Objective

To compare postoperative analgesia following either intraperitoneal (IP) ropivacaine or bupivacaine in dogs undergoing ovariohysterectomy (OVH) in the scope of multimodal analgesia.

Combination of magnesium sulphate and ropivacaine epidural analgesia for hip arthroplasty in dogs

Objective

The aim of this study was to determine whether lumbosacral epidural administration of magnesium sulphate added to ropivacaine prolongs and improves perioperative analgesia, without adverse effects on motor block duration or hind limb neurological function, in dogs undergoing hip arthroplasty.

Evaluation of nalbuphine,butorphanol and morphine in dogs during ovariohysterectomy and on early postoperative pain

ObjectiveTo evaluate the effects of nalbuphine, butorphanol and morphine combined with acepromazine on intraoperative and early postoperative pain management in dogs anesthetized for ovariohysterectomy.Study designProspective, randomized blinded clinical study.AnimalsA total of 48 healthy female dogs of different breeds, aged 1–6 years, weighing (mean ± standard deviation) 14.5 ± 4.8 kg.MethodsDogs were randomly assigned into four groups to be intravenously administered nalbuphine (0.5 mg kg^–1; group N0.5), nalbuphine (1.0 mg kg^–1; group N1.0), butorphanol (0.4 mg kg^–1; group B0.4) or morphine (0.2 mg kg^–1; group M0.2) combined with acepromazine (0.02 mg kg^–1) prior to propofol and isoflurane for anesthesia. Heart rate (HR), respiratory rate, systolic arterial pressure and rectal temperature (RT) were recorded at time points during anesthesia. A dynamic interactive visual analog scale applied in three phases (DIVAS I, II and III) and the modified Glasgow composite measure pain scale were used to assess pain before premedication and 1, 2, 3, 4, 5 and 6 hours after extubation. Administration of rescue analgesia was recorded.ResultsAt the left ovarian pedicle ligation, HR was higher in N1.0 than in B0.4 (p = 0.020). RT decreased significantly by the end of surgery in N0.5 (p = 0.043) and B0.4 (p = 0.010). Rescue analgesia was administered postoperatively over 6 hours to eight, seven, nine and 10 dogs in N0.5, N1.0, B0.4 and M0.2, respectively (p = 0.57). DIVAS II was higher in B0.4 than in N1.0 at 2 and 3 hours (p = 0.038 and p = 0.002, respectively) and N0.5 at 3 hours (p = 0.003).Conclusions and clinical relevanceAt the doses used, all premedication protocols provided insufficient intraoperative analgesia, with minimal clinical differences between groups. No premedication provided satisfactory analgesia in the first 6 hours postoperatively.     

Antinociceptive activity of pre- versus post-operative intra-articular bupivacaine in goats undergoing stifle arthrotomy

ObjectiveTo evaluate the peri-operative analgesic efficacy of intra-articular bupivacaine administered before or after stifle arthrotomy.Study designProspective, randomized, blind, placebo-controlled experimental trial.AnimalsThirty-nine healthy goats.MethodsThe goats were allocated randomly to one of three intra-articular treatment groups: group PRE (bupivacaine before and saline after surgery), group POST (saline before and bupivacaine after surgery) and group CON (saline before and after surgery). Anaesthesia was maintained with a constant end-tidal sevoflurane of 2.5%. Intra-operatively heart rate (HR), respiratory rate and mean arterial blood pressure (MAP) after critical surgical events (CSE) were recorded and compared with pre-incision values. Propofol requirements to maintain surgical anaesthesia were recorded. Flunixin was administered for 5 days. Post-operative pain assessment at 20 minutes, 2 hours, 4 hours after recovery and on day 2 and 3 included a multidimensional pain score (MPS), a lameness score and mechanical nociceptive threshold (MNT) testing. Rescue analgesia consisted of systemic opioids. Data were analysed using Kruskal–Wallis, Mann–Whitney, Friedman or chi-square tests as appropriate.ResultsIntra-operatively, group PRE had lower HR and MAP at several CSEs than groups POST/CON and required less propofol [0 mg kg^?1 (0–0 mg kg^?1)] than group POST/CON [0.3 mg kg^?1 (0–0.6 mg kg^?1)]. Post-operatively, group POST had significantly higher peri-articular MNTs than groups PRE and CON up to 4 hours after recovery. No treatment effect was detected for MPS, lameness scores and rescue analgesic consumption at any time point.Conclusions and clinical relevancePre-operative intra-articular bupivacaine provided notable intra-operative analgesia in goats undergoing stifle arthrotomy but did not reduce post-operative pain. Post-operative intra-articular bupivacaine provided a short lasting reduction of peri-articular hyperalgesia without affecting the requirements for systemic analgesia. Multimodal perioperative pain therapy is recommended to provide adequate analgesia for stifle arthrotomy in goats.     

Assessment of postoperative pain after unilateral mastectomy using two different surgical techniques in dogs

Background

There are few studies reporting pain and postoperative analgesia associated with mastectomy in dogs. The aim of this study was to evaluate postoperative pain after unilateral mastectomy using two different surgical techniques in the dog.

Findings

Twenty female dogs were assigned (n=10/group) to undergo unilateral mastectomy using either the combination of sharp and blunt dissection (SBD) or the modified SBD (mSBD) technique, in which the mammary chain is separated from the abdominal wall entirely by blunt (hand and finger) dissection except for a small area cranial to the first gland, in a prospective, randomized, clinical trial. All dogs were premedicated with intramuscular acepromazine (0.05 mg/kg) and morphine (0.3 mg/kg). Anesthesia was induced with intravenous ketamine (5 mg/kg) and diazepam (0.25 mg/kg), and maintained with isoflurane. Subcutaneous meloxicam (0.2 mg/kg) was administered before surgery. Postoperative pain was evaluated according to the University of Melbourne pain scale (UMPS) by an observer who was blinded to the surgical technique.. Rescue analgesia was provided by the administration of intramuscular morphine (0.5 mg/kg) if pain scores were >14 according to the UMPS. Data were analyzed using t-tests and ANOVA (P>0.05). There were no significant differences between the groups for age, weight, extubation time, and duration of surgery and anesthesia (P>0.05). There were no significant differences for postoperative pain scores between groups. Rescue analgesia was required in one dog in each group.

Conclusions

The two surgical techniques produced similar surgical times, incidence of perioperative complications and postoperative pain. Multimodal analgesia is recommended for treatment of postoperative pain in dogs undergoing unilateral mastectomy.     

Comparison of bupivacaine femoral and sciatic nerve block versus bupivacaine and morphine epidural for stifle surgery in dogs

ObjectiveTo evaluate the efficacy of combined femoral and sciatic nerve blocks as an alternative to epidural anesthesia and analgesia in dogs undergoing stifle surgery under general anesthesia.Study designProspective, blinded, randomized, clinical comparison.AnimalsTwenty dogs weighing 37 ± 11 (mean ± SD) kg, aged 3 (1–8) [median (minimum–maximum)] years undergoing elective unilateral tibial-plateau leveling osteotomy.MethodsDogs were assigned randomly to receive either epidural anesthesia (bupivacaine 0.5%, 0.5 mg kg^?1 + morphine 0.1%, 0.1 mg kg^?1, in 0.2 mL kg^?1; EPID) or femoral and sciatic nerve blocks (Bupivacaine 0.5%, 0.1 mL kg^?1, was administered at each site; F + S) guided by electrolocation. All patients received a standard general anesthesia technique. Pain and sedation were scored (on scales of 0–10 and 0–3, respectively) pre-operatively, at extubation, and at 1, 4 and then every 4 hours thereafter up to 24 hours. Postoperatively, hydromorphone was administered to any patient with a pain score of >5 or whenever the blinded caregiver determined that more hydromorphone was necessary. Intraoperative heart rate (HR), mean arterial pressure (MAP), end tidal isoflurane (FE′ISO), body temperature, post-operative pain scores, time to first hydromorphone dose after surgery, time to first feeding, time to first drinking, time to first urination, time to first ambulation (walk on a lead) and cumulative dose of hydromorphone were recorded.ResultsIntra-operatively, FE′ISO and MAP were significantly lower in the EPID group (p = 0.05 and p = 0.04, respectively). Postoperatively, the cumulative hydromorphone consumption (p = 0.04) and the incidence of urinary retention (p = 0.03) were higher in the EPID group.Conclusion and clinical relevance F + S is a practical alternative to EPID that produces less urine retention and reduces opioid consumption in the 24 hours after surgery. EPID might be associated with a lower isoflurane requirement and lower systemic blood pressure.     

Comparison of analgesic efficacy of epidural methadone or ropivacaine/methadone with or without pre‐operative oral tepoxalin in dogs undergoing tuberositas tibiae advancement surgery

ObjectiveTo investigate the clinical efficacy of four analgesia protocols in dogs undergoing tibial tuberosity advancement (TTA).Study designProspective, randomized, blinded study.AnimalsThirty-two client owned dogs undergoing TTA-surgery.MethodsDogs (n= 8 per treatment) received an oral placebo (PM and PRM) or tepoxalin (10 mg kg^?1) tablet (TM and TRM) once daily for 1 week before surgery. Epidural methadone (0.1 mg kg^?1) (PM and TM) or the epidural combination methadone (0.1 mg kg^?1)/ropivacaine 0.75% (1.65 mg kg^?1) (PRM and TRM) was administered after induction of anaesthesia. Intra-operative fentanyl requirements (2 μg kg^?1 IV) and end-tidal isoflurane concentration after 60 minutes of anaesthesia (Fe′ISO₆₀) were recorded. Post-operative analgesia was evaluated hourly from 1 to 8 and at 20 hours post-extubation with a visual analogue scale (VAS) and the University of Melbourne Pain Scale (UMPS). If VAS > 50 and/or UMPS > 10, rescue methadone (0.1 mg kg^?1) was administered IV. Analgesic duration (time from epidural until post-operative rescue analgesia) and time to standing were recorded. Normally distributed variables were analysed with an F-test (α = 0.05) or t-test for pairwise inter-treatment comparisons (Bonferonni adjusted α = 0.0083). Non-normally distributed data were analysed with the Kruskall–Wallis test (α = 0.05 or Bonferonni adjusted α = 0.005 for inter-treatment comparison of post-operative pain scores).ResultsMore intra-operative analgesia interventions were required in PM [2 (0–11)] [median (range)] and TM [2 (1–2)] compared to PRM (0) and TRM (0). Fe′ISO₆₀ was significantly lower in (PRM + TRM) compared to (PM + TM). Analgesic duration was shorter in PM (459 ± 276 minutes) (mean ± SD) and TM (318 ± 152 minutes) compared to TRM (853 ± 288 minutes), but not to PRM (554 ± 234 minutes). Times to standing were longer in the ropivacaine treatments compared to TM.Conclusions and clinical relevanceInclusion of epidural ropivacaine resulted in reduction of Fe′ISO₆₀, avoidance of intra-operative fentanyl administration, a longer duration of post-operative analgesia (in TRM) and a delay in time to standing compared to TM.     

Tramadol plus metamizole combined or not with anti‐inflammatory drugs is clinically effective for moderate to severe chronic pain treatment in cancer patients

ObjectiveTo test the effectiveness and safety of tramadol plus metamizole combined or not with a non-steroidal anti-inflammatory drug (NSAID) for treating moderate to severe chronic neoplastic pain in dogs, and its impact on quality of life (QL).Study designProspective, uncontrolled, open-label, clinical study.AnimalsSixty nine client-owned dogs with multiple forms of cancer and visual analog scale (VAS) pain score ≥40 after receiving NSAIDs for at least 7 days.MethodsThe MN group received metamizole + NSAID, MNT group received metamizole + NSAID + tramadol and MT group received metamizole + tramadol. Pain was scored by the 0 to 100 mm VAS (0 = no pain, 100 = worst pain) and analgesic therapy was considered effective if 25 mm differences in VAS scores were observed between day 0 and the follow ups. The QL was evaluated according to a 0 to 36 scoring method for dogs (0 = worst, 36 = best) and side effects were recorded. Data were registered at day 0 (baseline) and at the first and second follow ups (7 and 14 days after day 0, respectively).ResultsThe MN group had less analgesia at day 7 (25%) and day 14 (42%) than MNT (59%, p = 0.0274; 76%, p = 0.0251, respectively) and MT groups (69%, p = 0.0151; 81%, p = 0.0341, respectively). The QL scores were lower in the MN group at the first (score 23) and second follow up (score 26) than in MNT (27, p = 0.0847; 30, p = 0.0002) and MT (28, p = 0.0384; 31, p = 0.0001) groups. Side effects were more commonly observed in the MN group (87%) than in MNT (24%, p < 0.0001) and MT groups (25%, p = 0.0003) at the first follow up.Conclusions and clinical relevanceTramadol plus metamizole combined or not with NSAID were well tolerated and clinically effective to treat moderate to severe pain in dogs with cancer and improved QL.     

Epidural administration of combinations of ropivacaine,morphine and xylazine in bitches undergoing total unilateral mastectomy: a randomized clinical trial

ObjectiveTo investigate the epidural administration of combinations of ropivacaine, morphine and xylazine in bitches undergoing unilateral mastectomy.Study designProspective, randomized, blinded, clinical study.AnimalsA total of 22 bitches scheduled to undergo unilateral mastectomy for mammary tumor excision.MethodsDogs were anesthetized with acepromazine (0.02 mg kg^–1) and morphine (0.3 mg kg^–1) intramuscularly, propofol intravenously (IV) and isoflurane. Prior to the beginning of surgery, dogs were randomly administered one of three epidural treatments: ropivacaine (0.75 mg kg^–1) with morphine (0.1 mg kg^–1) (group RM, n = 7); ropivacaine with xylazine (0.1 mg kg^–1) (group RX, n = 8); or ropivacaine with morphine and xylazine (group RMX, n = 7). Cardiopulmonary variables and the expired concentration of isoflurane (Fe′Iso) were recorded intraoperatively. Meloxicam (0.1 mg kg^–1) was administered IV during skin closure. Postoperative pain scores were evaluated with the Glasgow composite measure pain scale short form for 24 hours, and rescue analgesia with morphine (0.5 mg kg^–1) was administered intramuscularly when pain scores were ≥ 6/24.ResultsFe′Iso was significantly higher in group RM than in groups RX and RMX. Heart rate decreased significantly in groups RX and RMX, but blood pressure remained within acceptable values. The number of dogs administered rescue analgesia within 24 hours was significantly higher in group RX (seven dogs, 87.5%) than in groups RM (one dog, 14.3%; p = 0.01) and RMX (two dogs, 28.6%; p = 0.04). Time to standing was significantly longer in group RX than in group RM.Conclusions and clinical relevanceAll epidural treatments provided adequate antinociception with minimal cardiovascular adverse effects during mastectomy. The inclusion of morphine (groups RM and RMX) provided the best postoperative analgesia. Owing to the undesirable effect of xylazine on ambulation, the combination ropivacaine–morphine appeared to provide greater benefits in bitches undergoing unilateral mastectomy.     

A comparison of epidural analgesia provided by bupivacaine alone,bupivacaine + morphine,or bupivacaine + dexmedetomidine for pelvic orthopedic surgery in dogs

ObjectiveTo compare the analgesic efficacy of bupivacaine, bupivacaine + morphine, or bupivacaine + dexmedetomidine administered epidurally in dogs undergoing pelvic limb orthopedic surgery.Study designProspective, randomized, double blinded clinical trial.AnimalsSixty dogs weighing (mean ± SD) 35 ± 15.7 kg, aged 5 ± 3 years.MethodsDogs were assigned to receive a lumbosacral epidural containing bupivacaine (B) 0.5%, 1 mg kg^?1; B, bupivacaine 0.5%, 1 mg kg^?1 + morphine 1%, 0.1 mg kg^?1; B + M, or bupivacaine 0.5%, 1 mg kg^?1 + dexmedetomidine 0.05%, 4 μg kg^?1; B + D. The anesthetic protocol was standardized. The median expired isoflurane concentration (E′Iso) and requirement for additional induction agent preventing purposeful movement were recorded. Pain was scored using visual analog (VAS) and modified University of Melbourne (UMPS) pain scales. Sedation was assessed using a 0–4 scale. All parameters were recorded preoperatively, and at extubation (t = 0), then at 1, 2, 4, 8, 12, 16, and 20–24 hours. Hydromorphone was administered postoperatively to patients with a VAS ≥ 35 and/or UMPS ≥ 9. Time to first voluntary urination and first motor activity were recorded.ResultsPostoperatively, B + D had a lower UMPS pain score than B at t = 1 hour (p = 0.013), but not compared to B + M. The B + D group had a shorter time to urination (p = 0.0131) and a longer time for return of motor function (p = 0.0068). There were no other differences between the treatments.Conclusion and clinical relevanceEpidurally administered B, B + M, or B + D in dogs all provided acceptable analgesia to manage post–operative orthopedic pelvic limb pain. Epidural administration of B + D is an effective alternative to the analgesia provided by B or B + M, but is associated with increased time to return of motor function. The direct neurotoxic effects of epidural dexmedetomidine have not been fully tested.