Comparison of Intra-articular 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 stabilization as a result of cranial cruciate ligament rupture. Dogs were premedicated with acepromazine, induced with thiopental, and maintained with halothane in oxygen. Preoperatively, dogs were assigned to one 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 saline (1 mL/5 kg body weight saline plus the volume of saline representing 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 representing 0.1 mg/kg of morphine) and epidural saline (1 mL/5 kg body weight saline plus the volume of saline representing 0.1 mg/kg of morphine). Group 3 (n = 6) received intra-articular saline (1 mL/10 kg body weight of saline plus the volume of saline representing 0.1 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 subjective and objective variables. Serum Cortisol and blood glucose concentrations were measured. Butorphanol was used to provide analgesia as needed based on a predetermined maximum pain score. Supplemental analgesics were required postoperatively every 2 to 3 hours for 6 hours in all dogs that did not initially receive analgesics (group 2). Pain scores were significantly lower in dogs administered morphine intra-articularly (group 1) and epidurally (group 3) at 30 minutes and 30, 120, and 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 difference 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 of morphine can produce effective analgesia in dogs comparable with that produced by epidural administration of morphine.     

Postoperative analgesia in dogs receiving epidural morphine plus medetomidine

This investigation was carried out to compare the postoperative analgesia and plasma morphine concentrations in dogs given epidural morphine or epidural morphine combined with medetomidine prior to surgery. Twelve dogs (seven males and five females) with ruptured cranial cruciate ligaments presented to the Washington State University Veterinary Teaching Hospital. Six dogs received an epidural injection of morphine (0.1 mg/kg) and six dogs received epidural morphine (0.1 mg/kg) combined with medetomidine (0.005 mg/kg). Numeric rating scale (NRS) pain scores and cumulative pain scores (CPS) were assigned to 10-min segments of video. Video segments, heart rates and respiratory rates were recorded prior to premedication and at 4, 8, 12, 18 and 24 h after epidural injection. Blood was sampled from the cephalic vein at each of these times and during anesthesia at 0.5, 1, 2 and 3 h after epidural injection. Data were analyzed using either Friedman's test or one-way anova for repeated measures. In the morphine group, significant increases compared with premedication values were detected at 4, 8 and 12 h after epidural injection for NRS and at 4 and 12 h after epidural injection for CPS. In the morphine plus medetomidine group, NRS was significantly higher at 4 and 8 h whereas there were no differences from baseline values for CPS. Plasma morphine concentrations were not significantly different between treatment groups, but were significantly increased compared with preinjection values at 0.5, 1, 12, 18, and 24 h in the morphine plus medetomidine group. Epidurally administered morphine combined with medetomidine was associated with only minor benefits based on subjective pain scoring when compared with morphine alone in these dogs undergoing repair of a ruptured cranial cruciate ligament.     

Controlled, clinical trial assessing saphenous, tibial and common peroneal nerve blocks for the control of perioperative pain following femoro-tibial joint surgery in the nonchondrodystrophoid dog

OBJECTIVE: To determine whether bupivacaine peripheral nerve block of the saphenous, tibial and common peroneal nerves proximal to the femoro-tibial joint reduces peri-operative pain following extracapsular surgical stabilization of cranial cruciate ligament rupture in the nonchondrodystrophoid dog. ANIMALS: Forty-one dogs with naturally acquired femoro-tibial joint instability. Study design Randomized, controlled, clinical trial. METHODS: Dogs diagnosed with suspected cranial cruciate ligament injury based on physical and radiographic evidence were randomly assigned to treatment (bupivacaine) or control (saline) nerve blocks before femoro-tibial joint surgery. Pain scores, skin sensation, pain threshold to incisional pressure, time to first systemic 'rescue' opioid analgesic and total analgesic dose were evaluated for 24 hours. p < 0.05 was considered significant. RESULTS: Treatment dogs had a significantly longer period of cutaneous desensitization than control dogs. There were no significant differences between treatment and control groups for pain score, pain threshold to incisional pressure, or time to first-rescue analgesic. The treatment group received significantly more supplemental analgesics than the control group. CONCLUSIONS: These peripheral nerve blocks were easy to perform and resulted in significant desensitization of the associated nerve autonomous zones, but did not improve post-operative analgesia. CLINICAL RELEVANCE: Clinical benefit was not detected when using this technique for peri-operative pain management following extracapsular cranial cruciate ligament surgical stabilization.     

Sprayed intraperitoneal bupivacaine reduces early postoperative pain behavior and biochemical stress response after laparoscopic ovariohysterectomy in dogs

This study investigated the use of sprayed intraperitoneal bupivacaine to relieve postoperative pain behavior and biochemical stress response after laparoscopic ovariohysterectomy (LOVH) in dogs. Sixteen sexually intact female dogs were randomly assigned to two groups. The sprayed intraperitoneal bupivacaine (SIB) group received 4.4 mg/kg of sprayed intraperitoneal bupivacaine diluted to 0.25% with an equivalent volume of saline after pneumoperitoneum. The control group received 1.76 mL/kg of saline in a similar fashion. Both groups received preoperative periportal 5% bupivacaine (1 mL) before incision. Postoperative pain was measured using the short form of the Glasgow composite measures pain scale (CMPS-SF, 0-24). Serum cortisol and glucose concentrations were measured preoperatively and 0.5, 1, 2, 4, 6, 12, and 24h postoperatively. The SIB group had significantly lower CMPS-SF compared to the control group 1, 2, 4, 6, and 12h after the operation. Cortisol concentrations were significantly increased from preoperative concentrations in the control group at 0.5, 1, 2, and 4h post operation and at 0.5 and 1h post operation in the SIB group. No significant differences were seen in serum glucose within each group. This report suggests that the use of sprayed intraperitoneal bupivacaine can be used as part of a multimodal approach for pain management after LOVH in dogs.     

Comparison of perioperative analgesic protocols for dogs undergoing tibial plateau leveling osteotomy

OBJECTIVE: To compare effects of 3 commonly used perioperative analgesic protocols (epidural injection, intra-articular injection, and intravenous [IV] injection) for management of postoperative pain in dogs after tibial plateau leveling osteotomy (TPLO). STUDY DESIGN: Prospective, randomized clinical trial. ANIMALS: Fifty-six healthy dogs with naturally occurring cranial cruciate ligament rupture. METHODS: Dogs were premedicated with IV hydromorphone and acepromazine and were randomly assigned to receive either E (preoperative epidural injection with morphine and bupivacaine), IA (pre- and postoperative intra-articular injections of bupivacaine), or C (neither epidural morphine and bupivacaine, nor intra-articular bupivacaine). All dogs were administered hydromorphone (0.05 mg/kg IV) at extubation and as needed to maintain comfort postoperatively. Patients were observed and monitored 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) measuring device. Time to 1st dose and the total doses of hydromorphone required to achieve adequate comfort for each dog were recorded. RESULTS: 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). Although time to 1st intervention between Groups E and IA were longer for Group E, differences were not significant. To provide an adequate level of comfort, 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 data. CONCLUSIONS: In this study population, significant differences were seen in time to 1st hydromorphone dose between Groups E and IA compared with Group C. As well, more supplemental analgesia was administered to Group C compared with Group E to maintain the same level of postoperative comfort. Although differences between Groups E and IA tended to favor the epidural group, differences were minimal and not statistically significant. CLINICAL RELEVANCE: Our results suggest that regardless of analgesic protocol, measured indices of pain in dogs after TPLO can be minimized if dogs are continuously observed and appropriately supplemented with parenteral opioids. However, the frequency of postoperative opioid dosing can be minimized and may be a factor when contemplating supplementary use of epidural or intra-articular injections as part of a balanced analgesic approach.     

A Comparison of Epidural Saline, Morphine, and Bupivacaine for Pain Relief After Abdominal Surgery in Goats

The purpose of this study was to determine the analgesic efficacy of bupivacaine, morphine, or saline (control) when injected epidurally into the lumbosacral epidural space in goats after abdominal surgery. Goats received either bupivacaine (0.5%; 1.5 mg/kg in 0.9% sodium chloride solution), 0.9% sodium chloride solution (0.2 mL/kg), or preservative-free morphine (0.1 mg/kg). Total volume injected into the epidural space was 0.2 mL/kg for all groups. The variables evaluated were times to extubation, sternal recumbency, standing, and eating; heart and respiratory rates; and pain score. Only two of the goats in the bupivacaine group were able to stand on their hindlimbs before 6 hours. Time to eating was shorter for the saline group when compared with the bupivacaine group. Heart rate over all time in the saline group (137 ± 4 beats/min, mean ± SEM) was higher than the morphine (125 ± 3 beats/min) and bupivacaine groups (121 ± 3 beats/min). Respiratory rate over all time was increased in the saline group (26 ± 1 breaths/min) compared with the bupivacaine (24 ± 1 breaths/min) or morphine (24 ± 1 breaths/min) groups. At 50 minutes, the pain score for the saline group was higher than the morphine group. Pain score over all time in the saline group (1.5 ± 0.10) was higher than the morphine (1.2 ± 0.07) and bupivacaine (1.2 ± 0.04) groups. One goat in the saline group required two intravenous injections of flunixin meglumine for pain.     

Use of a continuous, local infusion of bupivacaine for postoperative analgesia in dogs undergoing total ear canal ablation

OBJECTIVE: To determine whether addition of a continuous, local infusion of bupivacaine would improve postoperative analgesia in dogs undergoing total ear canal ablation. DESIGN: Randomized controlled trial. ANIMALS: 16 dogs undergoing total ear canal ablation (12 unilaterally and 4 bilaterally with > 1 month between procedures). PROCEDURE: Dogs were randomly allocated to receive morphine (0.25 mg/kg [0.11 mg/lb]) at the end of the procedure (10 procedures) or morphine and a continuous, local infusion of bupivacaine (0.13 to 0.21 mg/kg/h [0.06 to 0.1 mg/lb/h]; 10 procedures). Dogs were observed for 48 hours after surgery. Additional doses of morphine were administered up to every 4 hours in dogs with signs of severe pain. RESULTS: Temperament, sedation, analgesia, and cumulative pain scores were not significantly different between groups any time after surgery. Recovery score was significantly higher for dogs that received bupivacaine than for control dogs 2 hours after extubation but not at any other time. Serum cortisol concentration was not significantly different between groups at any time but, in both groups, was significantly increased at the time of extubation, compared with all other observation times. Total number of additional doses of morphine administered was not significantly different between groups. Bupivacaine was not detected in the plasma of any of the dogs that received the local bupivacaine infusion. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that addition of a continuous, local infusion of bupivacaine did not significantly increase the degree of postoperative analgesia in dogs that underwent total ear canal ablation and were given morphine at the end of surgery.     

Epidural anesthesia with bupivacaine, bupivacaine and fentanyl, or bupivacaine and sufentanil during intravenous administration of propofol for ovariohysterectomy in dogs

OBJECTIVE: To compare cardiovascular and systemic effects and analgesia during the postoperative period of epidural anesthesia performed with bupivacaine alone or with fentanyl or sufentanil in bitches maintained at a light plane of anesthesia with continuous infusion of propofol. STUDY DESIGN: Prospective randomized masked clinical trial. ANIMALS: 30 female dogs of various breeds. PROCEDURES: Dogs were allocated into 3 groups of 10 each. One group received fentanyl (2 microg/kg [0.91 microg/lb]) and bupivacaine (1 mg/kg [0.45 mg/lb]), 1 group received sufentanil (1 microg/kg) and bupivacaine (1 mg/kg), and 1 group received bupivacaine (1 mg/kg). All dogs received acepromazine (0.1 mg/kg [0.045 mg/lb]) and continuous infusion of propofol for sedation. The agents were administered into the lumbosacral space and diluted in saline (0.9% NaCl) solution to a total volume of 0.36 mL/kg (0.164 mL/lb). Cardiac and respiratory rates, arterial blood pressures, pH, and blood gases were evaluated. Analgesia, sedation level, serum cortisol concentrations, and plasma catecholamine concentrations were measured regularly for 6 hours. RESULTS: No important changes in cardiovascular, respiratory, or sedation variables were observed. Degree of analgesia in the postoperative period was higher in the sufentanil group, although use of fentanyl and bupivacaine also resulted in a sufficient level of analgesia. CONCLUSIONS AND CLINICAL RELEVANCE: Use of the 3 anesthetic techniques permitted ovariohysterectomy with sufficient analgesia and acceptable neuroendocrine modulation of pain with minimal adverse effects.     

Effects of tramadol,morphine or their combination in dogs undergoing ovariohysterectomy on peri-operative electroencephalographic responses and post-operative pain

Abstract

AIM: To compare the peri-operative electroencephalogram (EEG) responses and post-operative analgesic efficacy of pre-operative morphine or tramadol with a combination of low-dose pre-operative morphine and post-operative tramadol, in dogs undergoing ovariohysterectomy.

METHODS: Dogs undergoing routine ovariohysterectomy were treated with either pre-operative morphine (0.5 mg/kg S/C, n=8), or tramadol (3 mg/kg S/C, n=8), or pre-operative low-dose morphine (0.1 mg/kg S/C) and post-operative tramadol (3 mg/kg I/V, n=8). All dogs received routine pre-anaesthetic medication, and anaesthesia was induced with I/V thiopentone to effect and maintained with halothane in oxygen. Respiratory rate, heart rate, end-tidal halothane tension (EtHal) and end-tidal CO₂ tension (EtCO₂) were monitored throughout surgery. The EEG was recorded continuously in a three electrode montage. Median frequency (F50), total power (Ptot) and 95% spectral edge frequency (F95) of the EEG power spectra were compared during different 100-second periods of surgery: prior to and during skin incision, ligation of each ovarian pedicle, ligation of uterine body and skin closure. Post-operatively, pain was assessed using the short form of the Glasgow composite measure pain scale (CMPS-SF).

RESULTS: There was no difference in F50 or Ptot of the EEG between baseline and noxious surgical events within each treatment group, or between the three groups (p>0.05). The mean F95 was higher during the first three periods of surgery for dogs administered tramadol and low-dose morphine than those that received 0.5 mg/kg morphine (p=0.001). Dogs that received low-dose morphine and tramadol had lower CMPS-SF pain scores after ovariohysterectomy than those that received either tramadol or morphine alone (p=0.001). There was no difference in pain scores between dogs in the latter two groups.

CONCLUSION AND CLINICAL RELEVANCE: Tramadol and morphine administered pre-operatively provided an equal degree of post-operative analgesia in dogs after ovariohysterectomy. A combination of pre-operative low-dose morphine and post-operative tramadol produced better post-operative analgesia than either drug administered alone pre-operatively. Administration of analgesics pre- and post-operatively could result in improved post-operative well-being of ovariohysterectomised dogs.     

An evaluation of the analgesic effects of meloxicam in addition to epidural morphine/mepivacaine in dogs undergoing cranial cruciate ligament repair

The analgesic efficacy of an epidural morphine/mepivacaine combination alone versus epidural morphine/mepivacaine in combination with meloxicam administered prior to the onset of anesthesia was assessed in 20 dogs undergoing cranial cruciate ligament repair. Numerical and visual analog pain scores were performed prior to anesthesia and at 6, 8, 12, 16, and 24 hours after epidural administration by a trained observer, blinded to treatment. An analgesiometer was used to determine the amount of pressure required to produce an avoidance response at the incision site. Animals that received meloxicam demonstrated a trend toward decreased pain scores over all time periods. Visual analog pain scores tended to be lower in dogs receiving meloxicam across all time periods, with a significant interaction between time and visual analog score at 6 and 8 hours (P < 0.05). No dogs receiving meloxicam required rescue analgesia, while 3 of 10 dogs in the epidural only group required rescue analgesia. Administration of meloxicam in addition to epidural morphine plus mepivacaine conveys improved analgesia as compared with epidural alone. Postoperative analgesia is reliably maintained for 24 hours following administration.     

The effects of preoperative extradural bupivacaine and morphine on the stress response in dogs undergoing femoro-tibial joint surgery

OBJECTIVE: To evaluate the efficacy of preoperative extradural bupivacaine and morphine in attenuating the stress response in dogs undergoing femoro-tibial joint surgery. STUDY DESIGN: Prospective clinical study. Animal population Twelve client-owned dogs undergoing surgery for either repair of cruciate ligament rupture (ten) or correction of luxating patella (two). Body masses ranged from 12 to 45 kg (mean: 28.58 +/- 18.38). Age ranged from 19 to 121 months (mean: 66.5 +/- 49.5). MATERIALS AND METHODS: Six of the dogs received extradural bupivacaine (up to 1.5 mg kg(-1)) combined with morphine (0.1 mg kg(-1); ED) while the other six received no extradural analgesia (C). The levels of cortisol, acute phase proteins (APPs), and red and white blood cell variables were measured in both groups of dogs before, and at various times after surgery. Pain was also assessed at various times after surgery. The number of postoperative morphine doses required, and their time of administration, was recorded for each animal. Method of statistical analysis Data were analysed using anova for repeated measures with p-values of <0.05 considered significant. RESULTS: 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 APPs or red and white cell variables between dogs receiving, and those not receiving extradural bupivacaine and morphine. Four dogs in the control group and one in the ED group required postoperative morphine. CONCLUSIONS AND CLINICAL RELEVANCE: Pre-emptive extradural bupivacaine and morphine was effective in lowering the neuroendocrine stress response (cortisol) in the ED group but had no effect on the inflammatory response (acute phase response).     

Evaluation of topical nalbuphine or oral tramadol as analgesics for corneal pain in dogs: a pilot study

Objective To evaluate the effectiveness of topical nalbuphine or oral tramadol in the treatment of corneal pain in dogs. Animals studied Fourteen male Beagle dogs. Procedures Dogs were divided into three treatment groups and sedated with dexmedetomidine (5 μ/kg IV). A 4 mm corneal epithelial wound was created in the right eye (OD) of all dogs. Sedation was reversed with atipamazole IM. All dogs received pre/post ophthalmic examinations. Post operatively, Group NB (n = 5) received topical 1% preservative‐free nalbuphine OD q8 h and an oral placebo PO q8 h. Group TR (n = 5) received tramadol (4 mg/kg) PO q8 h and topical sterile saline OD q8 h. Group CNTRL (n = 4) received topical sterile saline OD q8 h and an oral placebo q8 h. All dogs received topical 0.3% gentamicin OD TID until healed. Dogs were pain scored using a pain scoring system modified from the University of Melbourne pain scale at 0, 1, 2, 4, and 6 h, then every 6 h by observers masked to treatment, until corneal wounds were healed. Treatment failure was recorded if cumulative pain scores were above a minimum threshold of acceptable pain and rescue analgesia of morphine (1.0 mg/kg IM) was administered subsequently. Result Four dogs in Group NB, one dog in Group TR, and two dogs in Group CNTRL required rescue analgesia. There was no significant difference in the incidence of treatment failure between groups (P = 0.184). Mean time to rescue was 9.16 h. All corneal wounds were healed by 84 h. Conclusions The results of this study suggest tramadol rather than nalbuphine should be further investigated for the treatment of corneal pain.     

Gabapentin as an adjuvant for postoperative pain management in dogs undergoing mastectomy

This study aimed to evaluate the analgesic efficacy of gabapentin as an adjuvant for postoperative pain management in dogs. Twenty dogs undergoing mastectomy were randomized to receive perioperative oral placebo or gabapentin (10 mg/kg). All dogs were premedicated with intramuscular acepromazine (0.03 mg/kg) and morphine (0.3 mg/ kg). Anesthesia was induced with propofol (4 mg/kg) intravenously and maintained with isoflurane. Intravenous meloxicam (0.2 mg/kg) was administered preoperatively. Postoperative analgesia was evaluated for 72 hr. Rescue analgesia was provided with intramuscular morphine (0.5 mg/kg). Dogs in the Placebo group received significantly more morphine doses than the Gabapentin group (P=0.021), despite no significant differences in pain scores. Perioperative gabapentin reduced the postoperative morphine requirements in dogs after mastectomy.     

Evaluation of a local anesthetic delivery system for the postoperative analgesic management of canine total ear canal ablation--a randomized, controlled, double-blinded study

OBJECTIVE: To determine if a constant rate local anesthetic delivery system is more effective than continuous intravenous (IV) morphine infusion for postoperative analgesia. ANIMALS: Twenty client-owned dogs undergoing total ear canal ablation. METHODS: Dogs were randomly assigned to the lidocaine group (LID) or the morphine group (MOR). The LID group received a constant rate infusion of lidocaine locally and a continuous IV infusion of saline, while the MOR group received a constant rate infusion of saline locally and a continuous IV infusion of morphine. The primary investigator evaluated each patient and determined a hospital behavior score, anesthesia recovery score, preoperative pain score, and serial postoperative pain and sedation scores over 38 hours. Pain and sedation observations were videotaped and scored by three additional evaluators. Evaluators were blinded to treatment assignments. RESULTS: There were no significant differences in age, weight, hospital behavior scores or anesthesia recovery scores. The primary investigator's pain scores were not significantly different, but sedation scores were significantly lower for the LID group. Sedation and pain scores by the video evaluators were not significantly different between groups. Kappa agreement between observers was poor, but better agreement was noted between sedation scores than pain scores. Drug-related complications were significantly lower in the LID group (n = 0) compared with the MOR group (n = 5). Wound complications were not significantly different (LID = 4, MOR = 4). Intravenous delivery complications occurred in 12 (60%) patients. Local delivery complications occurred in five (25%) dogs. Delivery complications were not significantly different between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Continuous incisional lidocaine delivery was an equipotent and viable method of providing postoperative analgesia compared with IV morphine. Lidocaine delivery resulted in a trend toward lower pain scores, significantly lower sedation scores, and no dogs requiring analgesic rescue. Wound complications secondary to local infusion were minor and self-limiting. Drug-related complications occurred only in the MOR group.     

Analgesic effects of epidurally administered levogyral ketamine alone or in combination with morphine on intraoperative and postoperative pain in dogs undergoing ovariohysterectomy

OBJECTIVE: To evaluate the analgesic and adverse effects of epidurally administered levogyral (S[+]) ketamine alone or in combination with morphine on intraoperative and postoperative pain in dogs undergoing ovariohysterectomy. ANIMALS: 30 dogs scheduled for ovariohysterectomy. PROCEDURE: Dogs were randomly allocated to 1 of 3 groups. Dogs in group 1 received S(+) ketamine (1 mg/kg), dogs in group 2 received S(+) ketamine (0.5 mg/kg) and morphine (0.05 mg/kg), and dogs in group 3 received S(+) ketamine (1 mg/kg) and morphine (0.025 mg/kg). The skin was incised 15 minutes after epidural administration of analgesics. Heart rate (HR), respiratory rate (RR), systolic blood pressure (SBP), oxygen saturation as measured by pulse oximetry, and arterial blood gases were obtained before anesthesia, 15 minutes after epidural administration of analgesics, 15 and 30 minutes after initiation of surgery, and at the end of surgery. During the intraoperative period, an increase of > or =20% in baseline values for HR, RR, and SBP was considered a sign of intraoperative pain. Signs of pain and adverse effects were assessed at 2, 4, and 8 hours postoperatively. RESULTS: There were no significant differences in intraoperative or postoperative measurements among the 3 groups. No dogs had intraoperative signs of pain. Mean postoperative pain assessment scores were <3.5 in all 3 groups. Salivation was the most frequent adverse effect in dogs in groups 1 and 3, and sedation occurred more frequently in dogs in groups 2 and 3. CONCLUSIONS AND CLINICAL RELEVANCE: All 3 analgesic regimens provided good respiratory and cardiovascular stability intraoperatively and adequate postoperative analgesia with minimal adverse effects.     

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.     

Efficacy of Epidural Morphine Versus Intravenous Morphine for Post-Thoractotomy Pain in Dogs

We compared the effects of epidural and intravenous morphine on analgesic effectiveness, vital signs, cortisol and catecholamine concentrations in dogs. Twelve healthy mongrel dogs undergoing experimental thora-cotomy under non-opioid general anaesthesia were randomly assigned to two groups: group A (n=6) received 0.15 mg/kg morphine epidurally, and group B (n=6) received 0.15 mg/kg morphine IV. Postoperatively, animals were observed hourly for the first 10 hours, then at 18 and 24 hours, and heart rate, systolic and diastolic blood pressure, respiratory rate and pain score were measured. Serum cortisol and plasma catecholamines were measured at 0, 2, 4, 8 and 24 hours postoperatively. Epidural morphine was associated with a significant reduction in pain, cortisol levels, systolic blood pressure (all p<.01) and heart rate (p<.05). There was a direct correlation between pain score, cortisol and catecholamine concentrations in each group; both were lower in the group receiving epidural morphine. Our data indicate that epidural morphine is safe, effective and provides an alternative approach for treatment of post-thoracotomy pain.     

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.     

Use of low doses of ketamine administered by constant rate infusion as an adjunct for postoperative analgesia in dogs

OBJECTIVE: To compare indicators of postoperative pain and behavior in dogs with and without a low-dose ketamine infusion added to usual perioperative management. DESIGN: Prospective, randomized, blinded clinical study. ANIMALS: 27 dogs undergoing forelimb amputation. PROCEDURE: Dogs were anesthetized with glycopyrrolate, morphine, propofol, and isoflurane. Thirteen dogs were treated with ketamine IV, as follows: 0.5 mg/kg (0.23 mg/lb) as a bolus before surgery, 10 microg/kg/min (4.5 microg/lb/min) during surgery, and 2 microg/kg/min (0.9 microg/lb/min) for 18 hours after surgery. Fourteen dogs received the same volume of saline (0.9% NaCl) solution. All dogs received an infusion of fentanyl (1 to 5 microg/kg/h [0.45 to 2.27 pg/lb/h]) for the first 18 hours after surgery. Dogs were evaluated for signs of pain before surgery, at the time of extubation, and 1, 2, 3, 4, 12, and 18 hours after extubation. Owners evaluated their dogs' appetite, activity, and wound soreness on postoperative days 2, 3, and 4. RESULTS: Dogs that received ketamine infusions had significantly lower pain scores 12 and 18 hours after surgery and were significantly more active on postoperative day 3 than dogs that received saline solution infusions. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that perioperative administration of low doses of ketamine to dogs may augment analgesia and comfort in the postoperative surgical period.