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To compare perioperative opioid consumption in dogs undergoing pelvic limb surgeries and receiving a lumbosacral plexus block by combining a lumbar [lateral pre-iliac (LPI)] block with a lumbosacral trunk [i.e. parasacral (PS group) or greater ischiatic notch plane (GIN group)] block. Study design Retrospective, descriptive, exploratory, noninferiority cohort study. Medical records of 37 client-owned dogs were analyzed. Intraoperative (primary outcome) and postoperative (24 hours) opioid use, 24 hour cumulative pain scores and prevalence of complications were compared between the two groups. Opioid use was quantified in morphine equivalents (ME, mg kg–1). The noninferiority limit for intraoperative opioid consumption was set at 0.05 ME kg–1 hour–1. Demographic data, procedure duration, surgery type and perioperative dexmedetomidine and ketamine use were also collected. A t -test or Wilcoxon rank-sum test, a Fisher's exact test and multivariable linear regression were used. Significance was set at p < 0.05. The GIN and PS groups comprised 17 and 20 dogs, respectively. Total intraoperative ME consumption was 0.17 (0.11–0.21) and 0.22 (0.16–0.30) mg kg–1 hour–1 for the GIN and PS groups, respectively (p = 0.077). The noninferiority analysis adjusted by surgery type and body mass revealed that the mean difference between the groups (GIN – PS) was –0.039 (95% CI –0.11–0.03, p = 0.247) ME mg kg–1 hour–1, indicating that the GIN group was not inferior to the PS group regarding intraoperative ME consumption. Dexmedetomidine and ketamine use, postoperative ME consumption and pain scores were similar between groups. This retrospective study and preliminary observations support the clinical use of the GIN plane block, demonstrating its noninferiority to the PS block when combined with the LPI block for multimodal perioperative analgesia in dogs undergoing pelvic limb surgeries. [ABSTRACT FROM AUTHOR]

To develop and assess the feasibility, as a diagnostic block, of an ultrasound-guided lateral pericapsular hip desensitization (L-PHD) technique in dogs. Prospective, randomized, anatomical and feasibility study. A total of 11 canine cadavers and eight adult dogs scheduled for acetabular surgical denervation. After studying the ultrasound anatomy of the lateral aspect of the gluteal region and determining an acoustic window to perform an ultrasound-guided L-PHD in three canine cadavers, the right and left hemipelves of eight canine cadavers were injected in the interfascial plane located lateral (L L -PHD group) or medial (L M -PHD group) to the deep gluteal muscle, with 0.05 mL kg–1 of dye per hip on each cadaver. The staining of the pericapsular nerves was assessed by anatomical dissection. Then, the L M -PHD was performed using 2% lidocaine as a diagnostic block in dogs scheduled for acetabular surgical denervation. Positive predictive value (PPV) was calculated for those animals who had favorable outcomes after acetabular surgical denervation. The ultrasound-guided L L -PHD and L M -PHD could be performed by inserting the needle lateral and medial to the deep gluteal muscle. Ultrasound-guided L L -PHD stained the cranial gluteal nerve and its muscular branches in all injections and partially stained the lumbosacral trunk in two out of eight cadavers. The L M -PHD selectively stained the articular branches of the cranial gluteal nerve in all but one cadaver. The PPV for L M -PHD successful test prediction was 85.7% (95% confidence interval: 48.6% to 98.6%). and clinical significance Ultrasound-guided L M -PHD using 0.05 mL kg–1 of dye selectively stained the articular branches of the cranial gluteal nerve in canine cadavers. The L M -PHD technique is feasible and could be used as a diagnostic block before acetabular surgical denervation in dogs. [ABSTRACT FROM AUTHOR]

To evaluate the impact of a 30% end-inspiratory pause (EIP) on alveolar tidal volume (V Talv), airway (V Daw) and physiological (V Dphys) dead spaces in mechanically ventilated horses using volumetric capnography, and to evaluate the effect of EIP on carbon dioxide (CO 2) elimination per breath (Vco 2 br–1), PaCO 2, and the ratio of PaO 2 -to-fractional inspired oxygen (PaO 2 :F i O 2). Prospective research study. A group of eight healthy research horses undergoing laparotomy. Anesthetized horses were mechanically ventilated as follows: 6 breaths minute–1, tidal volume (V T) 13 mL kg–1, inspiratory-to-expiratory time ratio 1:2, positive end-expiratory pressure 5 cmH 2 O and EIP 0%. Vco 2 br–1 and expired tidal volume (V TE) of 10 consecutive breaths were recorded 30 minutes after induction, after adding 30% EIP and upon EIP removal to construct volumetric capnograms. A stabilization period of 15 minutes was allowed between phases. Data were analyzed using a mixed-effect linear model. Significance was set at p < 0.05. The EIP decreased V Daw from 6.6 (6.1–6.7) to 5.5 (5.3–6.1) mL kg–1 (p < 0.001) and increased V Talv from 7.7 ± 0.7 to 8.6 ± 0.6 mL kg–1 (p = 0.002) without changing the V TE. The V Dphys to V TE ratio decreased from 51.0% to 45.5% (p < 0.001) with EIP. The EIP also increased PaO 2 :F i O 2 from 393.3 ± 160.7 to 450.5 ± 182.5 mmHg (52.5 ± 21.4 to 60.0 ± 24.3 kPa; p < 0.001) and Vco 2 br–1 from 0.49 (0.45–0.50) to 0.59 (0.45–0.61) mL kg–1 (p = 0.008) without reducing PaCO 2. The EIP improved oxygenation and reduced V Daw and V Dphys , without reductions in PaCO 2. Future studies should evaluate the impact of different EIP in healthy and pathological equine populations under anesthesia. [ABSTRACT FROM AUTHOR]

To describe an ultrasound-guided lateral pre-iliac (LPI) and parasacral (PS) approach in feline cadavers (phase I) and compare the perioperative analgesic use and complications in cats administered LPI and PS blocks (group PNB) or epidural anesthesia (group EPI) for pelvic limb surgery (phase II). Experimental uncontrolled, anatomic and retrospective cohort study. A group of eight feline cadavers and 52 medical records. Bilateral LPI and PS approaches with 0.1 mL kg–1 of dye to stain the femoral and obturator nerves and the lumbosacral trunk, respectively, were performed on each cadaver. Nerve staining effect was evaluated upon dissections (phase I). Perioperative analgesics use, and complication rates were retrospectively compared between groups PNB and EPI (phase II). Continuous data were compared using the Mann–Whitney U test and the prevalence of events with Fisher's exact test. Differences were considered significant when p < 0.05. Dissections revealed that the LPI approach stained 94% and 75% of the femoral and obturator nerves, respectively. The PS approach stained 100% of the lumbosacral trunks. Cats enrolled in group PNB (n = 23) were administered lower doses of intraoperative opioids than those in group EPI (n = 25) (p = 0.006). Intraoperative rescue analgesia was required in 60% and 17.4% of cats enrolled in groups EPI and PNB, respectively (p = 0.003). Group PNB required more intraoperative anticholinergics than group EPI (p = 0.02). There were no differences in postoperative pain scores, analgesic use and complication rates. The ultrasound-guided LPI and PS approach stained the femoral/obturator nerves and the lumbosacral trunk, respectively, in feline cadavers. Furthermore, PNB was associated with lower intraoperative opioid use and similar postoperative pain and analgesic use compared with epidural anesthesia in a cohort of cats undergoing surgery of the pelvic limb. [ABSTRACT FROM AUTHOR]

To develop and assess the efficacy of an ultrasound (US)-guided pericapsular hip desensitization (PHD) technique in dogs. Prospective, randomized, anatomical study and a case series. A total of 30 healthy dogs, eight canine cadavers and seven dogs with hip osteoarthritis. After studying the US anatomy of the medial aspect of the coxofemoral joint and determining an acoustic window to perform an US-guided PHD in healthy dogs, the US-guided PHD was performed bilaterally in canine cadavers. A low [(LV) 0.1 mL kg–1] and high [(HV) 0.2 mL kg–1] volume of dye was injected per hip on each cadaver. The staining of the pericapsular nerves was assessed by anatomical dissection, and comparison between LV and HV was assessed using Fisher's exact test. Then, the US-guided PHD was performed using a triamcinolone–bupivacaine solution in dogs with hip osteoarthritis. Dynamic pain response was assessed before and after injection. The canine brief pain inventory (CBPI) questionnaire was used to assess treatment efficacy and duration. The US-guided PHD could be performed by inserting the needle between the iliopsoas muscle and the periosteum of the ilium. The articular branches of the femoral and obturator nerves were stained in all cadavers using both volumes. The main femoral nerve was never stained, but the main obturator nerve was stained in 37.5% and 100% of injections using LV and HV, respectively (p = 0.026). Treated animals showed decreased dynamic pain response after the injection. Compared with baseline, CBPI scores were reduced by ≥ 50% for ≥ 12 weeks in all but one dog. The US-guided PHD with both 0.1 and 0.2 mL kg–1 volumes stained the articular branches of the femoral and obturator nerves in canine cadavers and was associated with clinical improvement in dogs with hip osteoarthritis. [ABSTRACT FROM AUTHOR]

To develop an ultrasound-guided approach to intercostal nerve injection and to compare the success rate of intercostal nerve injections using blind or ultrasound-guided technique in canine cadavers. Prospective, randomized, descriptive, experimental anatomic study. A total of 14 mid-sized adult canine cadavers. Ultrasound landmarks were identified by dissection of four cadavers and used to develop an ultrasound-guided technique. The remaining 10 cadavers were randomly assigned to blind (five cadavers) or ultrasound-guided (five cadavers) injections of the third to the ninth intercostal nerves bilaterally with 0.03 mL kg–1 of colorant per injection. The target for intercostal injections was the caudal border of the respective rib, between the internal intercostal membrane and the parietal pleura. Additionally, displacement of the parietal pleura without visible intramuscular distribution was considered the end point for ultrasound-guided injections. For each cadaver, a practitioner in training performed the blocks on one hemithorax, while an experienced practitioner performed the blocks on the opposite hemithorax. Injections were considered successful if ≥1 cm of the target nerve was stained with colorant upon dissection. Success rates and length of nerve staining were analyzed with Fisher's exact and t tests, respectively. Data were considered statistically different with p < 0.05. Success rates of blind and ultrasound-guided technique were 57.1% and 91.4%, respectively (p < 0.0001). The length of intercostal nerve staining was 3.1 ± 1.2 cm and 3.6 ± 1.0 cm using blind and ultrasound-guided techniques, respectively (p = 0.02). No differences were observed between the two practitioners for blind (p = 0.33) and ultrasound-guided techniques (p = 0.67). Ultrasound guidance improves the accuracy of intercostal nerve injections when compared with blind technique, independently of the level of expertise in regional anesthesia. [ABSTRACT FROM AUTHOR]

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. Retrospective cohort study. Medical records of 114 client-owned dogs. 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. 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. 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. [ABSTRACT FROM AUTHOR]

To compare the dye distribution following either two lateral abdominal or one lateral abdominal and one subcostal ultrasound-guided transversus abdominis plane (TAP) injections of a clinically relevant volume of dye solution in dogs. Randomized cadaveric study. A total of eight canine cadavers. On one side of each cadaver, two TAP injections were performed on the lateral aspect of the abdomen (approach LL), caudal to the last rib and cranial to the iliac crest. On the contralateral hemiabdomen, one subcostal (caudal to the costal arch) and one lateral abdominal injection (between last rib and iliac crest), were performed (approach SL). Side allocation was randomly determined. A spinal needle was introduced in-plane to the transducer for each injection of methylene blue (0.25 mL kg−1). All cadavers were dissected to assess dye distribution and number of stained target nerves. All injections were performed in the TAP. The proportion of target nerve staining was 53.5% versus 80.4% with approaches LL and SL, respectively (p = 0.005). Approach LL stained the first lumbar (L1) spinal nerve in 100% of injections and ninth thoracic (T9), T10, T11, T12, T13 and L2 were stained in 0%, 0%, 37.5%, 62.5%, 87.5% and 87.5% of injections, respectively. Approach SL stained T11, L1 and L2 in 100% of injections and T9, T10, T12 and T13 were stained in 37.5%, 87.5%, 75% and 62.5% of injections, respectively. Approach SL resulted in greater staining of nerves cranial to T12 compared with approach LL. The two approaches were equivalent in staining nerves caudal to T12. Approach SL provided a broader distribution of the injected solution than approach LL, which may result in a larger blocked area in live animals undergoing celiotomy. [ABSTRACT FROM AUTHOR]

To describe an ultrasound-guided lateral quadratus lumborum (LQL) block technique and the spread characteristics of lidocaine–dye injected in the LQL plane using a transversal (LQL-T) or a longitudinal (LQL-L) approach. Experimental anatomic study. A total of eight canine cadavers. Bilateral ultrasound-guided injections in the fascial plane lateral to the quadratus lumborum muscle and medial to the thoracolumbar fascia (LQL plane) with the needle directed at the first lumbar (L1) transverse process were performed using lidocaine–dye (0.3 mL kg−1). Anatomical dissection determined the dye distribution, sympathetic trunk staining and number of spinal nerves stained circumferentially >1 cm. The LQL fascial plane was ultrasonographically recognized in all cadavers and filled with lidocaine–dye in all eight cadavers with the LQL-T approach and in six with LQL-L. The injectate spread ventral to the lumbar transverse processes, around the quadratus lumborum muscle and dorsal to the transversalis fascia, affecting the ventral branches of the spinal nerves and the sympathetic trunk. A median (range) of 4 (3–5) and 3 (0–4) ventral branches of the thoracolumbar nerves were dyed with LQL-T and LQL-L approaches, respectively (p = 0.04). The most cranial nerve stained was the twelfth thoracic (T12) with the LQL-T approach and T13 with LQL-L, and the most caudal was L3 with both approaches. The incidence of sympathetic trunk staining was significantly higher using LQL-T (six injections) compared with LQL-L (one injection; p = 0.04). Dye was not observed in the lumbar plexus, epidural space or abdominal cavity. Ultrasound-guided LQL-T approach resulted in a more consistent spread toward the spinal nerves and sympathetic trunk compared with LQL-L approach. Further studies are necessary to assess the LQL block effectiveness and success rate in live dogs. [ABSTRACT FROM AUTHOR]

To describe a quadratus lumborum (QL) block technique in canine cadavers and the spread of injectate. Prospective, randomized, descriptive, experimental anatomic study. A group of 12 adult canine cadavers. Gross and ultrasound anatomy of the sublumbar musculature and the relationship with the spinal nerves was studied in two cadavers. Bilateral ultrasound-guided injections were performed in eight cadavers in the fascial plane between the QL and psoas muscle using a dye–lidocaine solution [low volume (LV) 0.15 mL kg–1 or high volume (HV) 0.3 mL kg–1]. The ultrasound transducer was positioned caudal and parallel to the proximal aspect of the last rib, and an insulated needle was introduced in-plane using a ventrolateral to dorsomedial approach. Dissections were performed to determine the number of spinal nerves successfully stained (>1 cm) and the presence of injectate in the epidural space or abdominal cavity. Additionally, two cadavers were transversally cryosectioned after QL injection. Ventral branches of the last thoracic and first three lumbar spinal nerves ran between the bundles of the QL muscle and between the QL and psoas muscles. The target fascial plane was ultrasonographically identified and filled with the dye solution following all injections. Ventral branches of the thirteenth thoracic and first, second and third lumbar nerves were stained by 0.0%, 71.4%, 100%, 100%, and 25%, 100%, 100%, 100% using LV and HV, respectively. Multisegmental spread stained the lumbar sympathetic trunk on 0 (0–3) and 3 (0–4) vertebral levels with LV and HV, respectively. No abdominal or epidural spread was identified. Although no significant differences were found, HV resulted in a higher percentage of stain on spinal nerves and sympathetic trunk than LV. Further studies are warranted to determine if the QL block provides somatic and visceral abdominal analgesia in dogs. [ABSTRACT FROM AUTHOR]

To investigate the distribution and nerve staining of two volumes of lidocaine–dye solution after ultrasound-guided erector spinae plane (ESP) injections in canine cadavers. Experimental cadaveric study. A total of nine canine cadavers. ESP injections were performed between the longissimus thoracis muscle and the dorsolateral edge of the ninth thoracic transverse process. Two cadavers were transversally cryosectioned after unilateral ESP injections [0.6 mL kg–1; high volume (HV)]. In seven cadavers, bilateral ESP injections with HV or low volume (0.3 mL kg–1; LV) were performed. Gadodiamide was added to the injectate for two cadavers and magnetic resonance imaging (MRI) was performed pre- and post-injection. Injectate distribution and nerve staining of the branches of the spinal nerves were recorded after gross anatomical dissection. The thoracic paravertebral and epidural spaces were examined for dye solution. Cryosections, MRI and gross dissections showed that the injectate spread dorsally to the transverse processes, over the ventromedial aspect of the longissimus thoracis muscle where the medial and lateral branches of the dorsal branches of the spinal nerves are located. LV and HV stained a median (range) of 4 (2–7) and 4 (3–8) medial branches, respectively (p = 0.52). LV and HV stained 4 (2–5) and 5 (4–7) lateral branches (p = 0.26), respectively. Ventral branches were not stained, and dye was not identified in the epidural or paravertebral spaces. and clinical relevance Medial and lateral branches were consistently stained over several spinal segments. The number of nerves stained was not different with HV or LV, and the ventral branches of the spinal nerves were not stained in any cadaver. ESP block may find a clinical application to desensitize structures innervated by the medial and lateral branches of the dorsal branches of the thoracic spinal nerves. [ABSTRACT FROM AUTHOR]

To evaluate whether fentanyl administered at analgesic doses in pain-free anesthetized dogs increases the serum cortisol or blood glucose concentrations and is associated with postanesthetic dysphoria. Experimental, blinded, randomized crossover. A group of six adult research dogs. Each dog was anesthetized twice and was administered fentanyl or saline with a 15-day wash-out period. Treatment allocation was randomly assigned via a closed envelope technique. Cortisol and glucose concentrations were measured on arrival in the research room (T PRE), induction of general anesthesia (T IND), extubation (T EXT) and 1 hour after extubation (T POST). Dogs were premedicated with methadone (0.1 mg kg−1) and carprofen (4 mg kg−1) intravenously (IV), anesthesia induced with propofol (4–6 mg kg−1) IV and maintained with isoflurane in oxygen. Standard anesthesia monitoring was performed throughout the experiment. Fentanyl (5 μg kg−1 over 90 seconds followed by 7.5 μg kg−1 hour −1) or an equivalent amount in mL of saline solution were administered IV for 60 minutes. T PRE behavior scores and recovery scores were evaluated using descriptive 4-point scales. Data from serum cortisol and blood glucose concentrations were analyzed with a Split Plot on time test, whereas recovery scores were analyzed using a Wilcox match-pairs signed rank test. Statistical significance was set at p < 0.05. There were no significant increases in serum cortisol and blood glucose concentrations over time, and there were no differences between treatments. None of the dogs developed postanesthetic dysphoria with either treatment. Fentanyl, administered at analgesic doses to healthy, pain-free, anesthetized dogs, was not associated with significant changes in serum cortisol or glucose concentrations in the studied population. [ABSTRACT FROM AUTHOR]

To test whether labetalol improved cardiovascular function in anaesthetized dogs injected with dexmedetomidine. Prospective, randomized, blinded, clinical trial. A group of 20 healthy client-owned dogs undergoing ovariohysterectomy. Each dog received dexmedetomidine (5 μg kg–1) and methadone (0.2 mg kg–1) intramuscularly. General anaesthesia was induced with propofol and maintained with isoflurane in oxygen. All dogs were mechanically ventilated, and epidural anaesthesia with lidocaine was performed. Standard anaesthetic monitoring, invasive blood pressure, oesophageal Doppler and near-infrared tissue perfusion/oxygenation were applied. Peak velocity (PV), mean acceleration and stroke distance (SD) from the oesophageal Doppler were recorded. Arterial elastance (Ea) was calculated. Tissue oxygenation (rStO 2) was also recorded. Prior to surgery, animals received either 0.1 mg kg–1 of labetalol intravenously (IV) over 60 seconds or the equivalent volume of saline. Data were recorded for 20 minutes. Age, weight and propofol dose were compared with a Wilcoxon rank-sum test. The effects of time, treatment and their interaction with haemodynamic and perfusion variables were analysed with mixed-effect models and Tukey's post hoc tests. Significant effects of the interaction between treatment and time were observed whereby heart rate (HR) was higher in dogs given labetalol (p = 0.01), whereas arterial blood pressure and Ea were lower (p < 0.01). Similarly, PV, SD and rStO 2 were higher in the labetalol group, and significant effects were detected for the interaction between treatment and time (p < 0.01). Labetalol at a dose of 0.1 mg kg–1 IV in dogs under general anaesthesia and administered a pre-anaesthetic medication of dexmedetomidine produced mild vasodilation (reduction of Ea), resulting in an increase in HR and left ventricular outflow. Although labetalol could be an effective option to achieve haemodynamic optimization after dexmedetomidine-induced vasoconstriction, future studies are needed to assess long-term effects. [ABSTRACT FROM AUTHOR]

Objective To describe ultrasound-visualized anatomy and the spread characteristics of a dye injected in the thoracic paravertebral (TPV) space under ultrasound guidance. Study design Anatomic cadaver study. Animals Seven dog cadavers. Methods One cadaver was used to observe, identify, and describe the relevant TPV anatomy. In the remaining six, the left fifth TPV space was randomly assigned to be injected with either a low volume (LV; 0.05 mL kg-1) or high volume (HV; 0.15 mL kg-1) of dye. Subsequently, the contralateral side was injected with the alternative volume. Anatomic dissections were conducted to determine the incidence of complete spinal nerve staining (>1 cm circumferential coverage), number of contiguous spinal nerves dyed and the absence or presence of solution in particular locations. Results The ultrasound-visualized anatomy of the TPV space was defined as the intercostal space abaxial to the vertebral body, delimited by the parietal pleura ventrally and the internal intercostal membrane dorsally. The endothoracic fascia divides the paravertebral space into dorsal and ventral compartments. The target nerve was completely dyed in five of six and six of six injections in the LV and HV conditions, respectively. In one LV injection, the nerve was partially dyed. No multisegmental spread affecting contiguous spinal nerves was found in either treatment. Multisegmental spread was found in the ventral compartment of the TPV space, affecting the sympathetic trunk on 3 (0-3) and 3.5 (1-6) vertebral spinal levels in the LV and HV conditions, respectively, but differences between volumes were not significant. No intrapleural, ventral mediastinal or epidural migration was observed. Conclusions and clinical relevance Ultrasoundguided TPV block is a potentially reliable technique. The LV appeared sufficient to dye a single spinal nerve and multiple sympathetic trunk vertebral levels. Multiple TPV injections may be needed to provide adequate thoracic analgesia in dogs undergoing thoracic surgery. [ABSTRACT FROM AUTHOR]

Objectives To compare the effects of regional anaesthesia and opioid administration on adrenocortical and glycaemic responses, postoperative pain and recovery quality in dogs undergoing stifle surgery. Study design Prospective, blinded clinical study. Animals Forty-five dogs anaesthetized for tibial tuberosity advancement or tibial plateau levelling osteotomy, and 15 healthy dogs undergoing noninvasive orthopaedic diagnostic procedures. Methods The baseline behaviour of each dog was classified on a descriptive scale before anaesthesia. Dogs were anaesthetized using a standard protocol. Those undergoing surgery were randomly assigned to one of three intraoperative analgesia protocols: 1) peripheral (femoral and sciatic) nerve block (bupivacaine 0.5%; 0.15 mL kg -1 in each nerve; group PNB); 2) spinal anaesthesia (isobaric bupivacaine 0.5%; 0.05 mL kg -1; group SPI); and 3) intravenous fentanyl variable rate infusion and postoperative methadone (0.2 mg kg -1; group FEN). Blood samples were collected for measurement of cortisol and glucose concentrations on arrival (TAR), at induction (TIND), at tracheal extubation (TEXT), and 1 hour post-extubation (TPEX). After extubation, a researcher unaware of the dog's group assignment evaluated pain and recovery quality using the Glasgow Composite Measure Pain Scale (Short- Form) and a descriptive scale, respectively. Results Median recovery quality was significantly worse in group FEN (p < 0.0001) compared with all other groups. Postoperative pain scores were lower in group PNB compared with groups SPI and FEN. Cortisol and glucose concentrations increased significantly from TAR at TEXT and TPEX (p < 0.0001) in group FEN, and were unchanged from TAR in the other groups. Conclusions and clinical relevance Analgesia with a peripheral nerve block or spinal anaesthesia prevented the glycaemic and cortisol responses to surgery, promoted better recovery quality, and decreased postoperative pain scores compared with FEN. In the present study, the regional anaesthesia techniques used were found to be excellent alternatives to fentanyl administration. [ABSTRACT FROM AUTHOR]

History Eleven female dogs of different breeds undergoing unilateral radical ( n = 7) or regional abdominal mastectomy ( n = 4) received an ultrasound guided transverse abdominis plane block ( TAP-block). Physical examination Subjects showed single or multiple mammary tumours. Serum biochemistry, CBC and electrocardiogram were unremarkable. Eight animals were classified as ASA physical status II and 3 as ASA III. Management Dogs were premedicated with methadone [0.1 or 0.2 mg kg−1 intravenously (IV) or intramuscularly respectively] or fentanyl (2.5 μgkg−1 IV). Anaesthesia was induced with propofol and maintained with isoflurane or sevoflurane. Unilateral ultrasound guided TAP blocks were performed in the caudal and cranial abdomen with bupivacaine 0.25% (0.3 to 0.35 mL kg−1). Intercostal nerve blocks (T4 to T11) with bupivacaine 0.25% (0.013 to 0.04 mL kg−1) completed the blocked area in dogs undergoing radical mastectomy. Follow up The median (range) of end-expired isoflurane and sevoflurane necessary to maintain anaesthesia was 1.15 (1.07-1.22) and 2.07 (2.05-2.2) vol% respectively. A single administration of fentanyl (2.5 μg kg−1, IV) was administered to control nociception (defined as an increased heart rate or mean arterial blood pressure above 20% of the pre-incisional value) in four of 11 dogs. All dogs received carprofen (2 mg kg−1 subcutaneously) at the end of surgery. Post-operative pain, assessed for 120 minutes using the short form of Glasgow Composite Pain Scale (0-24), was always lower than 3. No rescue analgesia (allowed by the protocol) was required in this time. Conclusion Transverse abdominis plane block combined with intercostal nerve blocks may be useful to produce intraoperative anti-nociception and short term post-operative analgesia in dogs undergoing unilateral mastectomy. [ABSTRACT FROM AUTHOR]

Objective To determine the needle-to-nerve distances during electrical nerve location in dogs at different currents and pulse duration using a peripheral nerve stimulator ( PNS) under ultrasound control ( US), and the minimal electrical thresholds ( MET) necessary to obtain a motor response ( MR) after achieving needle-to-nerve contact. Study design Prospective in vivo experimental trial in a clinical setting Animals Thirty dogs, scheduled for locoregional anaesthesia of the sciatic nerve. Methods Needle-to-nerve distance was measured ultrasonographically after obtaining the MR of sciatic nerve with 2, 1 and 0.5 mA and pulse duration 0.1 ms (NS0.1). Thereafter the needle was placed in contact with the nerve and MET was determined. The procedure was repeated with 0.3 ms (NS0.3). Finally the needle was reintroduced to contact the sciatic nerve guided only by US, thus MET- US was determined. Data were analysed using Kruskal- Wallis or Mann- Whitney tests. Results Needle-to-nerve distances were greater when MR was obtained with 2 mA than with 1 and 0.5 mA at 0.1 and 0.3 ms. No significant differences were observed between the needle-to-nerve distances using 0.1 or 0.3 ms. The MET [median (range)] was 0.4 (0.18-1.3) mA in NS0.1, 0.32 (0.12-0.8) mA in NS0.3; while MET- US was 0.7 (0.32-1.5) mA. When the needle contacted the nerve, the MR achieved with currents below 0.3 mA was obtained in 17.2, 40 and 0% of cases using NS0.1, NS0.3 and US respectively. Conclusions and clinical relevance The electrical current necessary to obtain a MR decreased as the needle moved towards the nerve. However when the needle tip contacted the nerve, an MR with low current intensity could not be obtained. Thus the absence of motor response at currents below 0.3 mA cannot rule out needle-epineurium contact. When ultrasound is combined with PNS, it is more important to assess the correct needle position than searching for an MR at low currents. [ABSTRACT FROM AUTHOR]

Objective To describe a new approach to block the femoral nerve and to evaluate the distribution of a dye injected into the psoas compartment using a new femoral nerve block approach; to assess its clinical application, when combined with a sciatic nerve block, for surgical anaesthesia/analgesia of the pelvic limb in dogs. Study design Prospective anatomical, research and clinical study. Animals Two dog cadavers; two dogs that had to be euthanized for reasons unrelated to this study, and 15 dogs undergoing pelvic limb orthopaedic surgery. Methods Phase 1: anatomical dissections were performed to determine a simple method to approach the femoral nerve within the psoas compartment. Phase 2: 0.1 mL kg−1 of a lidocaine-new methylene blue solution was injected bilaterally after successful electrolocation of the femoral nerve in two anaesthetized dogs. Colorant spread was evaluated through femoral nerve dissections after euthanasia. Phase 3: in 15 dogs undergoing pelvic limb orthopaedic surgery under light general anaesthesia with isoflurane, intra-operative analgesic effect (cardiovascular responses) and early post-operative pain score, of the novel femoral nerve block combined with a sciatic nerve block as the sole analgesic protocol, were evaluated. Results Phase 1: a needle inserted from the lateral aspect of the lumbar muscles, cranially to the iliac crest and with a 30-45° caudo-medial direction, reaches the femoral nerve in the caudal portion of the psoas compartment. Phase 2: Four femoral nerves were stained >2 cm. Phase 3: this novel lateral pre-iliac approach, combined with the sciatic nerve block, blunted the intra-operative cardiovascular response to surgical stimulation in 13 out of 15 anaesthetized dogs. In addition, rescue analgesia was not required in the early post-operative 2-hour period. Conclusion and clinical relevance The lateral pre-iliac femoral nerve block technique may provide adequate intra- and early post-operative pain relief in dogs undergoing pelvic limb surgery. [ABSTRACT FROM AUTHOR]

To define the morbidity and mortality rates in goats undergoing general anesthesia at a large animal teaching hospital. Retrospective, single-cohort, observational study. Records of 193 client-owned goats. Data were collected from 218 medical records on 193 goats undergoing general anesthesia between January 2017 and December 2021. Demographic data, anesthetic management, recovery period and perianesthetic complications were recorded. Perianesthetic death was defined as anesthesia-related or anesthesia-contributory death occurring within 72 hours after recovery. Records of goats that were euthanized were reviewed to ascertain the cause of euthanasia. Each explanatory variable was individually investigated by univariable penalized maximum likelihood logistic regression, followed by multivariable analysis. Statistical significance was set at p < 0.05. Perianesthetic mortality was 7.3%, but was 3.4% when considering only goats undergoing elective procedures. Multivariable analysis showed that gastrointestinal surgeries [odds ratio (OR) 19.17, standard error (SE) 12.99, 95% confidence interval (CI) 5.08–72.33; p < 0.01] and requirement for perianesthetic norepinephrine infusion (OR 10.85, SE 8.82, 95% CI 2.21–53.33; p < 0.01) were associated with increased mortality. Maintaining other variables equal, the use of perianesthetic ketamine infusion was associated with decreased mortality (OR 0.09, SE 0.09, 95% CI 0.01–0.73; p = 0.02). Anesthesia-related or anesthesia-contributory complications included hypothermia (52.4%), bradycardia (38.1%), hypotension (35.3%), hypoxemia (14.8%), regurgitation/aspiration (7.3%), azotemia/acute renal failure (4.6%), myopathies/neuropathies (4.1%) and fever of unknown origin (2.7%). In this population, gastrointestinal surgeries and the requirement for perianesthetic norepinephrine infusion were associated with increased mortality in goats undergoing general anesthesia, while ketamine infusion may have a protective effect. [ABSTRACT FROM AUTHOR]

Objective To evaluate the endotracheal tube cuff pressure achieved by four different inflation methods. Study design Prospective clinical study. Animals Eighty client owned dogs. Methods After anaesthesia induction, endotracheal intubation was performed using plastic or silicone tubes. A clinician unaware of tube type inflated the cuff by simple digital palpation (method A), thereafter the cuff was deflated and inflated again by a second clinician who tried to reproduce a previously learned cuff pressure of between 19 and 24 mmHg (method B). During method C the cuff was inflated to the minimum occlusive volume at an airway pressure of 20 cm H2O, and in method D the cuff was incrementally deflated until an audible air leak could be heard from the oral cavity at an airway pressure of 25 cm H2O. For all the methods, an operator recorded the actual cuff pressure obtained using a manometer. Heart rate, respiratory rate and mean arterial pressure were monitored throughout the procedure. Results The mean inflation pressure for plastic tubes was 56 ± 28 mmHg for method A, 20 ± 9 mmHg for method B, 35 ± 32 mmHg for method C and 46 ± 39 mmHg for method D. Pressures using silicone tubes were significantly higher than for plastic tubes, the mean registered pressures being 79 ± 39, 33 ± 16, 77 ± 50 and 92 ± 56 mmHg for methods A, B, C and D. Conclusions and Clinical Relevance None of the methods evaluated in this study can be considered effective for inflating the endotracheal tube cuff to within the optimal range when using silicone tubes. Direct measurement of the cuff pressure with a manometer is therefore recommended. [ABSTRACT FROM AUTHOR]

Objective To describe the landmarks and methodology to approach the thoracic paravertebral space in dogs; to evaluate if intercostal muscular response could be evoked by a nerve-stimulator; to radiographically assess the distribution pattern of a radio-opaque contrast medium after thoracic paravertebral injections. Study design Randomized, controlled, experimental trial. Animals Two mongrel dog cadavers (anatomical study) and 24 mongrel dogs (experimental study). Methods For the anatomic study 0.2 mL kg−1 of new methylene blue (NMB) was injected at the 5th thoracic paravertebral space; for the experimental study dogs were divided into three groups and received 1 (T5), 2 (T4 and T6) or 4 (T4, T5, T6 and T7) paravertebral injections of iohexol. The paravertebral approach was performed with insulated needles using landmarks and a blind technique. When the needle tip reached the respective thoracic paravertebral space, the nerve-stimulator was switched-on and the presence/absence of intercostal muscular twitch was registered, thus a total volume of 0.2 mL kg−1 of iohexol, divided into equal parts for each injection point, was administered. Radiological studies were performed with two orthogonal projections at different times. Positive injection was confirmed when the paravertebral space was occupied by iohexol in both projections. Results NMB was distributed in the T5 paraverterbal space. In the experimental study, when the needle tip reached the respective paravertebral space, intercostal twitching was obtained in 80% of the total injections with a stimulating current of 0.5 mA. The incidence of positive cases when the intercostal twitch was obtained with 0.5 mA was 83.3%. The main distribution pattern observed was cloud like without longitudinal diffusion. Conclusion and clinical relevance Intercostal muscular responses obtained with a stimulating current of 0.5 mA could be useful to locate thoracic spinal nerves in dogs and in our study the injected solution was confined to one thoracic paravertebral space. [ABSTRACT FROM AUTHOR]

Objective To evaluate the effectiveness of paravertebral lumbar plexus block combined with parasacral sciatic block to anesthetize one hind limb in awake dogs. Study design Randomized, controlled, blinded experimental study. Animals Eight healthy mongrel dogs weighing 12.4 ± 4.5 kg and aged 7 ± 2.33 years. Methods After sedation with medetomidine, dogs received B1: bupivacaine 0.25%, 0.2 mL kg−1, B2: bupivacaine 0.5%, 0.2 mL kg−1, B3: bupivacaine 0.25% 0.4 mL kg−1, P1: NaCl 0.2 mL kg−1, P2: NaCl 0.4 mL kg−1. The lumbosacral plexus was blocked through a paravertebral block of the fourth, fifth and sixth lumbar nerves combined with a parasacral block. The relevant nerves were located using a nerve stimulator and injections of each treatment were administered. Degree and durations of sensory blockade were determined through the response to a Halsted clamp pressure on the skin innervated by the saphenous/femoral and lateral cutaneous femoral nerves (lumbar dermatomes) and by the peroneal and tibial nerves. The degree and duration of motor blockade was assessed evaluating the ability to walk normally and proprioception. Results P1 and P2 treatments did not show any grade of sensory or motor blockade. The B2 treatment produced a higher degree of sensory blockade compared to B1 and B3 for both lumbar and sciatic dermatomes. There was no significant difference in the degree of sensory blockade comparing B1 to B3. The B2 treatment had greater motor blockade compared to B1 and B3. The duration of sensory and motor blockade was longer in B2 compared to B1 and B3. Conclusion and clinical relevance When the nerve stimulator is used to perform the lumbosacral plexus block, the concentration of the bupivacaine has a more important role than the volume to produce a more solid and longer block. [ABSTRACT FROM AUTHOR]

To evaluate the feasibility of an ultrasound-guided technique targeting the medial branches of the dorsal ramus of the spinal nerves (DRSN) by injecting a dye solution at the caudal aspect of the base of lumbar mammillary processes [i.e. the retromammillary (RM) space]. Feasibility, descriptive, anatomical study. Eleven canine cadavers. Using anatomical dissections, the relationship between the mammillary processes and the branches of the DRSN of the thoracolumbar and lumbar spine was studied in two cadavers. Subsequently, ultrasound-guided RM injections were administered in nine cadavers, randomly assigned to low volume (LV; 0.01 mL kg–1) of a dye solution at multiple points from L3 to L6 on one side, and high volume (HV; 0.4 mL kg–1) at a single L4 point on the contralateral side. Gross anatomical dissections were immediately performed after the injections. The RM injections were feasible if ultrasonographic landmarks were identifiable in at least 80% of cases, and 80% of LV injections showed medial branch staining. A one-sample binomial test was used for testing feasibility. The medial branches emerged shortly after the DRSN exited the intervertebral foramen and traveled towards the caudal aspect of the base of the mammillary process, which served as the target injection point. With LV, 36 out of 36 (100%) injected medial branches were stained, meeting the criteria of feasibility (p < 0.001). The median (range) number of stained medial branches per cadaver were 4 (4–4) and 2 (1–3), with LV and HV, respectively. Although no lateral branches were stained with LV, 1 (0–2) was stained with HV. Neither ventral branch staining nor epidural spread was noted in any cadaver. Ultrasound-guided RM injections are feasible and allow for selective staining of the medial branch of the DRSN in canine cadavers at the lumbar spine. [ABSTRACT FROM AUTHOR]

To compare the success rate and extent of sciatic nerve staining with a bupivacaine–dye solution using two injection techniques: 'blind' or ultrasound-guided approach. Prospective, experimental, randomized, cadaveric study. Adult female Wistar rat cadavers [ n = 24, mass 352 g (323–374)]. Each sciatic nerve was randomly allocated to one of two groups: 'blind' (group B) or ultrasound-guided approach (group US) to injection. Following injection of bupivacaine–dye solution (0.1 mL), gross anatomical dissection was performed to visualize nerve staining, categorizing it as either positive or negative. The length of nerve staining was then measured and visual inspection conducted to identify potential nerve damage. Fisher's exact test was used to compare positive or negative nerve staining, and the Wilcoxon signed rank test used to compare the length of nerve staining between groups. In group B, the bupivacaine–dye solution stained 16/24 sciatic nerves (67% success). In group US, staining was successfully observed in all 24 nerves (100% success, p < 0.004). The length of nerve staining [median (interquartile range)] was 2 (2–3) mm in group B and 5 (4–6) mm in group US (p < 0.001). One sciatic nerve in group B had injectate distributed over 16 mm, suggestive of an intraneural injection. No signs of laceration or nerve damage were visible under 6× magnification in either group. The ultrasound-guided approach for sciatic nerve injection demonstrated a higher success rate with superior injectate distribution when compared with the 'blind' approach. Ultrasound guidance is recommended over a 'blind' approach for sciatic nerve block in rats when possible. [ABSTRACT FROM AUTHOR]

To compare the perioperative cumulative opioid consumption and the incidence of cardiovascular complications in dogs undergoing hemilaminectomy in which either an erector spinae plane (ESP) block or systemic opioids were administered. Prospective randomized clinical trial. A total of 60 client-owned dogs. Dogs were randomized to one of three groups: an ESP block (group ESP), a constant rate infusion of fentanyl (group FNT, positive control) or a single dose of methadone as premedication (group MTD, negative control). Intraoperative nociceptive response was treated with fentanyl [1 μg kg–1, intravenously (IV)] boli. Before closure of the surgical site, morphine (0.1 mg kg–1) was applied to the dura mater. The cumulative dose of opioids was recorded and compared between groups. The incidence of intraoperative bradycardia and/or hypotension and the time to extubation were compared between groups. The short form of the Glasgow Composite Pain Scale (SF-GCPS) was used to score nociception before anaesthetic induction and 1, 2, 6, 12,18 and 24 hours postoperatively. Methadone 0.2 mg kg–1 was administered IV if the SF-GCPS score was ≥ 5. Group MTD required more intraoperative rescue analgesia than groups ESP (p = 0.008) and FNT (p = 0.001). The total cumulative intraoperative dose of fentanyl was higher in groups FNT (p < 0.0001) and MTD (p = 0.002) than in group ESP. The incidence of cardiovascular complications was similar between groups. Extubation time was longer in group MTD (p = 0.03). Postoperatively, the time to first rescue analgesia was longer in group ESP than in group MTD (p = 0.03). The cumulative postoperative opioid consumption and pain scores were similar between groups. The ESP block resulted in a reduced intraoperative opioid consumption compared with the control positive and negative groups. [ABSTRACT FROM AUTHOR]

To investigate the feasibility of an ultrasound-guided sciatic nerve block by describing the sonoanatomy and comparing the distribution of two volumes of bupivacaine dye solution for nerve staining. Randomized, experimental, assessor-blinded cadaveric study. A total of 40 adult female Wistar rat cadavers. After studying the sonoanatomy of the sciatic nerve and adjacent structures using a high-resolution linear transducer (19–5 MHz), rat cadavers were randomly divided into two groups that were administered either 0.1 mL (group 0.1) or 0.2 mL (group 0.2) of bupivacaine dye solution per nerve, delivered via an in-plane technique. The extent of nerve staining was subsequently evaluated following dissection. Statistical analysis consisted of assessing data distribution using the Shapiro–Wilk test, followed by paired t -tests for continuous data, Mann–Whitney U test and McNemar's test for categorical data. Statistical significance was defined as p < 0.05. The sciatic nerve was identified bilaterally as a double ellipsoid-shaped image, surrounded by a hyperechoic fascia separating the biceps femoris from the adductor muscle. The hypoechoic structure formed by the bupivacaine dye solution around the nerve was effectively visualized using ultrasound imaging. Sciatic nerve staining was successfully achieved in all pelvic limbs, with dye spread of 4.82 ± 1.55 mm and 5.47 ± 2.18 mm in groups 0.1 and 0.2, respectively (p = 0.128). This study achieved a detailed understanding of the sonoanatomy of the sciatic nerve and its adjacent structures, highlighting the feasibility of the ultrasound-guided technique for injection in Wistar rats. Furthermore, the results show a comparable distribution of dye solution in both groups. Use of the ultrasound-guided sciatic nerve block technique in rats not only exhibits substantial potential for regional anesthesia but also opens avenues for translational studies. [ABSTRACT FROM AUTHOR]

To develop an ultrasound-guided caudal quadratus lumborum block (C-QLB) technique in canine cadavers and to compare sensory and motor blockade resulting from the combination of ultrasound-guided greater ischiatic notch (GIN) plane and C-QLB approaches (GIN-CQLB group) versus a lumbosacral plexus (LSP group) approach [combination of lateral pre-iliac (LPI) and parasacral (PS) techniques] in dogs. Descriptive anatomical study and prospective randomized, blinded, experimental crossover trial. A total of six canine cadavers and six adult Beagle dogs. Phase I: following ultrasound-guided C-QLB injections of 0.3 mL kg–1 of dye, using the interfascial plane located lateral to the quadratus lumborum muscle at the level of the sixth lumbar vertebra (L6) as injection point, the spread of injectate and nerve staining was evaluated using gross anatomical dissection. Phase II: sensory and motor blockade achieved with the GIN-CQLB or LSP blocks in Beagle dogs were evaluated and compared. The assigned technique was performed with 2% lidocaine: 0.2 mL kg–1 for the GIN and PS approaches and 0.3 mL kg–1 for the C-QLB and LPI approaches. Dissection revealed distribution of dye around the lumbar hypaxial musculature, extending into the paravertebral spaces, with staining of 3 (2–4) [median (interquartile range)] spinal nerves, spanning L3 to L6. The median motor blockade in the GIN-CQLB and LSP groups was 7 (7–8) versus 16 (10–16) (p = 0.026), whereas the median sensory blockade was 5 (4–5) versus 3 (3–3) (p = 0.025), respectively. The GIN-CQLB approach desensitized the thigh dermatomes effectively. Compared with the LSP approaches, GIN-CQLB exhibits a motor-protective effect by preserving tonic muscle function. [ABSTRACT FROM AUTHOR]

To describe the gross and ultrasound anatomy of the parasacral region and an ultrasound-guided greater ischiatic notch (GIN) plane approach aimed at staining the lumbosacral trunk (LST) in canine cadavers. To evaluate if the ultrasound-guided GIN plane approach is non-inferior to the previously described ultrasound-guided parasacral approach at staining the LST. Prospective, randomized, non-inferiority experimental anatomic study. A total of 17 (23.9 ± 5.2 kg) mesocephalic canine cadavers. Anatomic and echographic landmarks, and the feasibility of performing a GIN plane technique were evaluated using two canine cadavers. The remaining 15 cadavers had each hemipelvis randomly assigned to be administered either parasacral or GIN plane injection of 0.15 mL kg–1 dye solution. The parasacral region was dissected after injections to assess the staining of LST, cranial gluteal nerve, pararectal fossa and pelvic cavity. The stained LST were removed and processed for histological evaluation of intraneural injections. A one-sided z-test for non-inferiority (non-inferiority margin –14%) was used to statistically evaluate the success of the GIN plane versus the parasacral approach. Data were considered statistically significant when p < 0.05. The GIN plane and parasacral approach stained the LST in 100% and 93.3% of the injections, respectively. The success rate difference between treatments was 6.7% [95% confidence interval, –0.6 to 19.0%; p < 0.001 for non-inferiority]. The GIN plane and parasacral injections stained the LST for 32.7 ± 16.8 mm and 43.1 ± 24.3 mm, respectively (p = 0.18). No evidence of intraneural injection was found. The ultrasound-guided GIN plane technique resulted in nerve staining that was non-inferior to the parasacral technique and may be considered an alternative to the parasacral approach to block the LST in dogs. [ABSTRACT FROM AUTHOR]

Objective To identify the dose of rocuronium that will prevent a laryngeal response to water spraying of the glottis in anesthetized cats. Study design Randomized crossover study. Animals Eight healthy, adult, short-haired cats, aged 1-4 years, weighing 3.2-6.0 kg. Methods Each cat was anesthetized four times and administered one of four doses of rocuronium (0.1, 0.2, 0.3 and 0.6 mg kg−1) in random order. The larynx was observed with a video-endoscope inserted through a laryngeal mask airway. Video-clips of the laryngeal response to a sterile water spray (0.2 mL) were obtained at baseline (without rocuronium) and at maximal effect of each treatment. Glottal closure score (0-2), duration of glottal closure, and number of adductive arytenoid movements were obtained from video-clips of laryngeal responses (reproduced in slow motion) at baseline and after treatment. Two observers blinded to treatment allocation scored the vigor of the laryngeal response on a visual analog scale ( VAS). The duration of apnea (up to 5 minutes) was recorded for each treatment. Results Compared with baseline, rocuronium 0.3 mg kg−1 and 0.6 mg kg−1 significantly decreased all glottal scores obtained from the videos (all p < 0.03). Both observers gave lower VAS scores after 0.3 mg kg−1 (both p = 0.015). Apnea lasting ≥ 5 minutes occurred in none, one, three and seven of eight cats administered doses of rocuronium 0.1, 0.2, 0.3 and 0.6 mg kg−1, respectively. Conclusions and clinical relevance Rocuronium 0.3 mg kg−1 and 0.6 mg kg−1 consistently decreased the completeness and duration of the laryngeal response to water spray, and reduced the number of arytenoid adductive movements in response to that stimulus. However, a laryngeal response was never completely prevented. Rocuronium 0.3 mg kg−1 may be useful for facilitating tracheal intubation. Positive pressure ventilation must be available for cats administered rocuronium. [ABSTRACT FROM AUTHOR]

To investigate the injectate spread and nerve staining of ultrasound-guided erector spinae plane (ESP) injections at the thoracolumbar spine in canine cadavers. Prospective, randomized, descriptive, anatomic study. A total of 15 canine cadavers. The location of the medial and lateral branches of the dorsal branches of the spinal nerves (DBSN) from the tenth thoracic (T10) to the third lumbar vertebra (L3) were identified by dissection of three cadavers. ESP injections of dye (0.5 mL kg–1) were performed in seven cadavers using as landmarks the T12 transverse process (ESP Tp) on one side and the lateral aspect of the T12 mammillary process (ESP Mp) on the opposite side. Additionally, five cadavers were injected with dye (0.5 mL kg–1) bilaterally on the lateral aspect of the L2 mammillary process (ESP Mp_L2). Nerve staining effect was analyzed after gross anatomic dissections. The number of stained nerves was analyzed using the Mann–Whitney U test. Gross anatomic dissections showed that the medial and lateral branches of the DBSN change their path in relation to the epaxial muscles caudal to T11. Approaches ESP Tp and ESP Mp at T12 stained 2 (0–2) and 3 (2–4) medial (p = 0.01) and 3 (3–4) and 2 (0–2) lateral (p = 0.03) branches, respectively. Injection ESP Mp_L2 stained 3 (2–4) medial and 2 (0–3) lateral branches. Injections ESP Mp and ESP Mp_L2 produced a preferential cranial spread from the injection site. No ventral branches of the spinal nerves were stained with either technique. These results suggest that the mammillary process should be used as anatomic landmark to perform ultrasound-guided ESP blocks in the thoracolumbar spine caudal to T11 when targeting the medial branches of the DBSN. Injections should be performed one spinal segment caudal to the level intended to desensitize. [ABSTRACT FROM AUTHOR]

To evaluate the use of 0.7 mA as a fixed electrical current to indicate epidural needle placement and to confirm that 0.7 mA is greater than the upper limit of the minimal electrical threshold (MET) for sacrococcygeal epidural needle placement in dogs. Prospective clinical study. A group of 20 client-owned dogs. During general anesthesia and with standard monitoring, the presence of the patellar reflex was confirmed in all dogs. An insulated needle was inserted through the sacrococcygeal intervertebral junction, and absence of tail movement was confirmed when a fixed electrical current of 0.7 mA was applied. Then, the needle was further advanced toward the epidural space until the expected motor response was obtained – the nerve stimulation test (NST). The NST was considered positive when a motor response of the muscles of the tail was elicited but not the perineal muscles, whereas it was considered negative when no movement of the tail was evoked. The electrical current was turned to 0 mA and then increased by 0.01 mA increments until tail movement was evoked; this was recorded as the MET. In the positive NST cases, 0.05 mL cm–1 occipitococcygeal length of 2% lidocaine or 0.25–0.5% bupivacaine was administered. Epidural blockade was confirmed by the loss of patellar reflex. Descriptive statistics were used to present data. Sacrococcygeal epidural needle placement, corroborated by loss of the patellar reflex, was correctly predicted in 89.5% (95% confidence interval, 68.6–97.1%) of the cases. The MET was 0.22 mA (0.11–0.36). A current of 0.7 mA is approximately twice the upper limit of the MET for epidural placement. Therefore, this study demonstrates, with a success rate of 89.5%, the adequacy of using 0.7 mA as the fixed electrical current to detect sacrococcygeal epidural needle placement in dogs. [ABSTRACT FROM AUTHOR]

To describe the sonoanatomy of the abdominal wall in live cats and to compare the distribution pattern of two versus three ultrasound-guided transversus abdominis plane (TAP) injections using clinically applicable volumes of lidocaine–dye solution in cat cadavers. Prospective anatomical study. A total of eight client-owned healthy cats and eight cat cadavers. Ultrasound anatomy of the abdominal wall, landmarks and sites for needle access were determined in live cats. Ultrasound-guided TAP injections were performed in eight thawed cat cadavers. Volumes of 0.25 or 0.16 mL kg−1 per point of a lidocaine–dye solution were injected using either two [subcostal and preiliac (SP)] or three [subcostal, retrocostal and preiliac (SRP)] injection points, respectively. Each cadaver was then dissected to determine the injectate distribution and the number of thoracolumbar nerves stained with each approach. The target nerves were defined as the ventromedial branches of the thoracic nerves 10 (T10), T11, T12, T13 and lumbar nerves 1 (L1) and L2. Sonoanatomy was consistent with anatomy upon dissection and the TAP was identified in all cadavers. A total of 16 subcostal, 16 preiliac and nine retrocostal TAP injections were performed. The overall staining success rate of the target nerves was 66.7% and 92.6% for the SP and SPR approaches, respectively (p = 0.02). The ventromedial branches of T10, T11, T12, T13, L1 and L2 were stained in 57.1%, 100.0%, 85.7%, 28.6%, 42.9% and 85.7%, and in 66.7%, 100.0%, 100.0%, 100.0%, 88.9% and 100.0% of the cases with the SP and SRP approaches, respectively. The SRP approach allowed a broader distribution around the target nerves, whereas a staining gap was observed at T13 and L1 with the SP approach. Further studies are necessary to investigate the analgesic effect of these approaches in a clinical setting. [ABSTRACT FROM AUTHOR]