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Objective: To develop an ultrasound (US)-guided ventral approach to the brachial plexus (BP) and evaluate nerve anatomy and staining in barred owl cadavers., Study Design: Prospective, cadaveric study., Animals: Eleven adult male and female barred owl cadavers with a body mass of 0.43-0.98 kg., Methods: Eleven frozen cadavers were thawed for 48 hours, weighed and assigned a body condition score. Ten cadavers were placed in dorsal recumbency with wings abducted. US-guided visualization of the BP was achieved by placing a 13-6 MHz linear probe over the ventral aspect of the scapulohumeral joint, parallel to the sternum. A 22 gauge, 50 mm insulated needle was advanced in-plane in a caudal-to-cranial direction. In each owl, injection targeting one BP was performed with 0.4 mL kg -1 of a 1:1 0.5% ropivacaine and 1% methylene blue solution. Dissection was performed 15 minutes postinjection. Nerve staining was deemed successful if ≥ 1 cm of circumferential staining was achieved. The eleventh owl cadaver was injected with a 1:1 solution of 1% methylene blue and 74% ioversol contrast into both wings, and computed tomography (CT) was performed just before and 15 minutes after injection., Results: The BP was clearly identified ultrasonographically in cadavers weighing > 0.5 kg. An injectate volume of 0.4 mL kg -1 provided complete staining of the BP branches in all cadavers. CT scan revealed no contrast within the coelomic cavity., Conclusions and Clinical Relevance: The US-guided BP injection using a ventral approach was easily performed in barred owl cadavers weighing > 0.5 kg. The injection of 0.4 mL kg -1 of a ropivacaine-dye solution resulted in complete staining of the BP branches in all wings, suggesting that this technique could provide analgesia for structures distal to the scapulohumeral joint. Clinical studies are necessary to confirm the safety and efficacy of this technique in barred owls and other bird species., (Published by Elsevier Ltd.)

Objective: To develop an ultrasound-guided interfascial plane technique for injection of the pudendal nerve near its sacral origin in cats., Study Design: Prospective, randomized, anatomical study., Animals: A group of 12 feline cadavers., Methods: Gross and ultrasound anatomy of the ischiorectal fossa, the pudendal nerve relationship with parasacral structures, and the interfascial plane were described. Computed tomography was employed to describe a cranial transgluteal approach to the pudendal nerve. Bilateral ultrasound-guided injections were performed in eight cadavers using low [(LV) 0.1 mL kg -1 ] or high volume [(HV) 0.2 mL kg -1 ] of ropivacaine-dye solution. Dissections were performed to determine successful staining of the pudendal nerve (>1 cm) and inadvertent staining of the sciatic nerve, and any rectal, urethral, or intravascular puncture. Pudendal nerve staining in groups LV and HV were compared using Fisher's exact and Wilcoxon rank-sum test as appropriate (p = 0.05)., Results: The pudendal nerve and its rectal perineal and sensory branches coursed through the ischiorectal fossa, dorsomedial to the ischiatic spine. The pudendal nerve was not identified ultrasonographically, but the target plane was identified between the sacral transverse process, the ischiatic spine, the pelvic fascia and the rectum, and it was filled with dye solution. Both branches of the pudendal nerve were completely stained 75% and 87.5% in groups LV and HV, respectively (p = 1.00). The dorsal aspect of the sciatic nerve was partially stained in 37% of injections in group HV. Rectal or urethral puncture and intravascular injection were not observed., Conclusions and Clinical Relevance: In cats, ultrasound-guided cranial transgluteal injection successfully stained the pudendal nerve in at least 75% of attempts, regardless of injectate volume. Group HV had a greater probability of sciatic nerve staining., (Published by Elsevier Ltd.)

Objective: To investigate the epidural administration of combinations of ropivacaine, morphine and xylazine in bitches undergoing unilateral mastectomy., Study Design: Prospective, randomized, blinded, clinical study., Animals: A total of 22 bitches scheduled to undergo unilateral mastectomy for mammary tumor excision., Methods: Dogs 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., Results: Fe'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 Relevance: All 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., (Copyright © 2021 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)

Objective: To compare the perioperative use of analgesics and complication rates in dogs administered an erector spinae plane (ESP) block or a traditional opioid-based (OP) treatment as part of analgesic management during hemilaminectomy., Study Design: Retrospective cohort study., Animals: Medical records of 114 client-owned dogs., Methods: General data included demographics, duration of procedure, number of laminae fenestrated, perioperative use of steroid and non-steroidal anti-inflammatory drugs. Intra- and postoperative analgesics used in 48 hours and complications rates were compared between groups. Opioid use was expressed in morphine equivalents [ME (mg kg -1 )]. Continuous data were compared using the Mann-Whitney U test and incidence of events with a Fisher's exact tests. Multiple linear regression was used to evaluate association between perioperative ME consumption (dependent variable) with other independent variables. Data are presented as median (range). Differences were considered significant when p < 0.05., Results: Group ESP comprised 42 dogs and group OP 72 dogs. No differences were observed in the general data. Intraoperative ME was 0.65 (0.20-3.74) and 0.79 (0.19-5.60) mg kg -1 in groups ESP and OP, respectively (p = 0.03). Intraoperative infusion of lidocaine was administered intravenously (IV) to 23.8% and 68% of groups ESP and OP, respectively (p < 0.0001). Intraoperative infusion of ketamine was administered IV to 21% and 40% of groups ESP and OP, respectively (p = 0.04). Regression analysis revealed the ESP block as the only independent variable affecting the perioperative ME consumption. Pharmacological intervention to treat cardiovascular complications was administered to 21.4% and 47.2% of dogs in groups ESP and OP, respectively (p = 0.008). There were no differences in postoperative complication rates., Conclusions and Clinical Relevance: ESP block was associated with reduced perioperative opioid consumption, intraoperative adjuvant analgesic use and incidence of pharmacological interventions to treat cardiovascular complications in dogs undergoing hemilaminectomy., (Copyright © 2020 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)

Objective: To evaluate motor and sensory blockade of combining dexmedetomidine with ropivacaine, administered perineurally or systemically, for femoral and sciatic nerve blocks in conscious dogs., Study Design: Randomized, controlled, experimental study., Animals: Seven healthy Beagle dogs, aged 3.3 ± 0.1 years and weighing 11.0 ± 2.4 kg., Methods: Dogs were anesthetized with isoflurane on three separate occasions for unilateral femoral and sciatic nerve blocks and were administered the following treatments in random order: perineural ropivacaine 0.75% (0.1 mL kg -1 ) on each nerve and intramuscular (IM) saline (0.2 mL kg -1 ) (G con ); perineural dexmedetomidine (1 μg mL -1 ) and ropivacaine 0.75% (0.1 mL kg -1 ) on each nerve and IM saline (0.2 mL kg -1 ) (G DPN ); and perineural ropivacaine 0.75% (0.1 mL kg -1 ) on each nerve and IM dexmedetomidine (1 μg mL -1 , 0.2 mL kg -1 ) (G dim ). Nerve blocks were guided by ultrasound and electrical stimulation and dogs were allowed to recover from general anesthesia. Sensory blockade was evaluated by response to clamp pressure on the skin innervated by the saphenous/ femoral, common fibular and tibial nerves. Motor blockade was evaluated by observing the ability to walk and proprioception. Sensory and motor blockade were evaluated until their full recovery., Results: No significant differences in onset time to motor and sensory blockade were observed among treatments. Duration of motor blockade was not significantly different among treatments; however, duration of tibial sensory blockade was longer in the G dpn than in the G DIM treatment., Conclusions and Clinical Relevance: Although a longer duration of sensory blockade was observed with perineural dexmedetomidine, a significant increase compared with the control group was not established. Other concentrations should be investigated to verify if dexmedetomidine is a useful adjuvant to local anesthetics in peripheral nerve blocks in dogs., (Copyright © 2016 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)