A novel approach to ear pain in the horse: A case report.

Background: During electrochemotherapy (ECT), a chemotherapeutic drug is injected into the tumor and then an electroporation is provided. In horses, ear manipulation may be very painful, and combining a loco-regional technique with sedation might be a good option to avoid anesthesia-related risks. A two-injection-point block of the internal and external pinna and acoustic meatus was described in horse cadavers, and it permitted complete stain of all three branches of the great auricular nerve (GAN), internal auricular nerve branch (IAB), lateral auricular branch (LAB), and caudal auricular nerve (CAN), suggesting a lower risk of intra-parotid injection during the IAB and LAB block. Case Description: An 8-year-old Italian jumping gelding presented for ECT to treat a fibroblastic sarcoid in the left medial pinna. After intravenous sedation with acepromazine, romifidine, and butorphanol, a two-injection-point block was provided as previously described. The block of the GAN was blind, whereas an electrical nerve locator was used for the IAB, LAB, and CAN. A total of 12 ml of 0.5% ropivacaine was injected. The ECT was safely performed without any difficulties. The horse well tolerated the procedure and completely recovered 75 minutes after sedation. No complications were detected. Conclusion: The described approach seems feasible and suitable for the blockade of the sensory innervation of the equine ear in the case of ECT.

Perioperative analgesic effects of the erector spinae plane block with bupivacaine or bupivacaine-dexmedetomidine in dogs undergoing hemilaminectomy: A randomized controlled trial.

Objective: To compare the perioperative opioid requirements among dogs receiving an erector spinae plane (ESP) block with bupivacaine, with or without dexmedetomidine, and a control group. Animals and procedure: Thirty client-owned, healthy adult dogs undergoing hemilaminectomy were included in this randomized, prospective, blinded clinical study. Dogs were randomly assigned to 1 of 3 treatment groups: Group B, ESP block with bupivacaine; Group BD, ESP block with bupivacaine and dexmedetomidine; and Group C, control. Rescue intra- and postoperative analgesia consisted of fentanyl and methadone, respectively. Postoperative pain was evaluated using the short form of the Glasgow Composite Measure Pain Scale (CMPS-SF). Results: In Group BD, 0/10 dogs required intraoperative fentanyl, compared to 9/10 in Group C (P < 0.001), whereas 1/10 required postoperative methadone, compared to 9/10 in Group B (P = 0.003) and 10/10 in Group C (P < 0.001). The total amount of intraoperative fentanyl (µg/kg) was 0 (0 to 4) in Group B and 0 (0 to 0) in BD, compared to 6 (0 to 8) in C (P = 0.004 and P < 0.001, respectively). Postoperative methadone (mg/kg) required during the first 12 h was 0.5 (0 to 1.4) in Group B (P = 0.003) and 0 (0 to 0) in BD (P < 0.001), compared to C (P = 0.003 and P < 0.001, respectively). Conclusion: An ESP block with bupivacaine, with or without dexmedetomidine, was associated with a reduction in perioperative opioid consumption and provided effective acute pain control.

Effets analgésiques périopératoires du bloc des érecteurs du rachis avec de la bupivacaïne ou de la bupivacaïne-dexmédétomidine chez les chiens subissant une hémilaminectomie: un essai contrôlé randomisé. Objectif: Comparer les besoins périopératoires en opioïdes chez les chiens recevant un bloc des érecteurs de la colonne vertébrale (ESP) avec de la bupivacaïne, avec ou sans dexmédétomidine, et un groupe témoin. Animaux et procédure: Trente chiens adultes en bonne santé appartenant à des clients subissant une hémilaminectomie ont été inclus dans cette étude clinique randomisée, prospective et en aveugle. Les chiens ont été répartis au hasard dans 1 des 3 groupes de traitement: groupe B, bloc ESP avec bupivacaïne; groupe BD, bloc ESP avec bupivacaïne et dexmédétomidine; et groupe C, témoin. L'analgésie de secours peropératoire et postopératoire consistait respectivement en fentanyl et en méthadone. La douleur postopératoire a été évaluée à l'aide du formulaire abrégé de l'échelle de mesure de la douleur de Glasgow (CMPS-SF). Résultats: Dans le groupe BD, 0/10 chiens ont eu besoin de fentanyl peropératoire, contre 9/10 dans le groupe C (P < 0,001), tandis que 1/10 ont eu besoin de méthadone postopératoire, contre 9/10 dans le groupe B (P = 0,003) et 10/10 dans le groupe C (P < 0,001). La quantité totale de fentanyl peropératoire (µg/kg) était de 0 (0 à 4) dans le groupe B et de 0 (0 à 0) dans le groupe BD, contre 6 (0 à 8) dans le groupe C (P = 0,004 et P < 0,001, respectivement). La méthadone postopératoire (mg/kg) nécessaire au cours des 12 premières heures était de 0,5 (0 à 1,4) dans le groupe B (P = 0,003) et de 0 (0 à 0) dans le groupe BD (P < 0,001), par rapport au groupe C (P = 0,003). et P < 0,001, respectivement). Conclusion: Un bloc ESP avec de la bupivacaïne, avec ou sans dexmédétomidine, a été associé à une réduction de la consommation peropératoire d'opioïdes et a permis un contrôle efficace de la douleur aiguë.(Traduit par Dr Serge Messier).

Retrospective comparison between low-volume high-concentration and high-volume low-concentration levobupivacaine for bilateral erector spinae plane block in dogs undergoing hemilaminectomy.

OBJECTIVE: To compare the analgesic effect of a bilateral ultrasound-guided erector spinae plane block (ESPB) in dogs undergoing hemilaminectomy using either a low-volume high-concentration (LV-HC) or a high-volume low-concentration (HV-LC) local anaesthetic solution. STUDY DESIGN: Retrospective observational equivalence trial. ANIMALS: A total of 391 client-owned dogs undergoing hemilaminectomy. METHODS: Dogs were assigned to group LV-HC or HV-LC depending on whether 0.2-0.25% levobupivacaine (0.4-0.5 mL kg-1) or 0.125-0.15% levobupivacaine (0.8-1 mL kg-1) was used to perform the ESPB, respectively. The number of dogs in which intraoperative rescue fentanyl boluses were administered, the total dose of fentanyl administered, the overall methadone consumption during the first 24 hours postoperatively and anaesthetic complications were recorded. Univariate and multivariate statistical analyses were performed considering p < 0.05 significant. RESULTS: A total of 248 and 143 dogs were assigned to groups LV-HC and HV-LC, respectively. In group HV-LC, the number of dogs requiring fentanyl intraoperatively (64.3%) was higher (p = 0.0001) than that in group LV-HC (43.5%). The overall intraoperative fentanyl consumption was higher in group HV-LC between the first skin incision and the end of the lamina drilling (p = 0.028). According to the regression analysis, the group allocation was the best variable to predict the intraoperative fentanyl consumption (p < 0.001). Antimuscarinic drugs were administered more frequently in group LV-HC (p < 0.02). However, the prevalence of hypotension and other pharmacological cardiovascular interventions did not differ between groups. No differences in methadone consumption during the first 24 hours postoperatively were found between the groups. CONCLUSIONSAND CLINICAL RELEVANCE: When performing a bilateral ESPB in dogs undergoing hemilaminectomy, compared with HV-LC, the use of LV-HC local anaesthetic solution reduces the intraoperative fentanyl consumption without affecting the postoperative methadone requirement.

Physiological variables for the objective detection of nerve block failure in dogs.

OBJECTIVE: To identify physiological variables for objectively detecting nociception indicative of intraoperative peripheral nerve block failure. STUDY DESIGN: A double-blinded randomized clinical study. ANIMALS: A sample of 14 male (40.8 ± 12 kg; mean ± standard deviation) and 16 female (34.3 ± 11.4 kg) client-owned dogs. METHODS: Dogs were randomly assigned to one of three groups for psoas compartment and proximal sciatic nerve blocks (0.2 mL kg-1 per site): guided bupivacaine (GBB), or saline (GSB) block or a blind bupivacaine block (BBB). Guided blocks were performed using an ultrasound-peripheral nerve locator combination. Premedication consisted of medetomidine 0.01 mg kg-1 and morphine 0.3 mg kg-1. General anaesthesia was induced with propofol and maintained with isoflurane in oxygen. Receiver operator characteristic curve analysis was used to compare actual values and change in values of physiological variables between GSB and GBB. The Youden index and associated criterion for each physiological variable were used to determine an objective measure for nociception. Fisher's exact t test, McNemar's test and Cohen's kappa statistical analysis were used to determine association, differences and inter-score reliability between the objective and subjective scoring for BBB. RESULTS: Cardiovascular variables had good discriminating ability to identify a nociceptive response (p < 0.01). The Youden indices for mean (MAP) and diastolic (DAP) arterial pressure were most reliable in detecting nociception. The highest sensitivity was that of ΔMAP (100%) with good agreement between the subjective and objective scores of Δheart rate or systolic arterial pressure (SAP). The use of ΔMAP, ΔSAP, ΔDAP had the best ability in indicating peripheral nerve block failure (p < 0.001). CONCLUSIONS AND CLINICAL RELEVANCE: Blood pressure values can detect a response to surgical stimulus in adequately anaesthetized dogs. The use of ΔMAP, ΔSAP or ΔDAP may be considered as objective measures to detect nerve block failure.

A randomized clinical trial comparing the efficacy of lidocaine administered intravenously, intranasally or as infraorbital nerve block in dogs undergoing rostral rhinosocopy.

OBJECTIVE: To compare the efficacy of lidocaine administered intravenously, intranasally or as an infraorbital nerve block in dogs undergoing rostral rhinoscopy. STUDY DESIGN: Randomized clinical trial. ANIMALS: A total of 43 client-owned dogs. METHODS: After premedication with medetomidine 0.01 mg kg-1 and methadone 0.2 mg kg-1 intramuscularly, anaesthesia was induced with propofol and maintained with isoflurane in oxygen. Dogs were randomly allocated to receive 2 mg kg-1 of 2% lidocaine as a bilateral infraorbital nerve block (INB) via the caudal intraoral approach, via bilateral topical intranasal administration (TIA) or as an intravenous bolus (IVB). At 5 minutes following lidocaine administration, responses to rhinoscopy (RR) and biopsies (RB) were evaluated using a simple scoring system (0: no reaction; 1: reaction). Response to the rhinoscopy in the recovery period (RE) was recorded. Recovery quality was scored using a simple descriptive score. Heart rate, respiratory rate and noninvasive arterial blood pressure were recorded. Intravenous (IV) fentanyl 0.001 mg kg-1 was administered if an increase > 20% in any variable occurred. Gross movement was attenuated using propofol 0.5 mg kg-1 IV. Scores were analysed using the Chi-square test with Monte Carlo method. Cardiorespiratory changes among and overtime between groups were compared using one-way anova and one-way anova for repeated measures, respectively, or the correspondent non-parametric tests; p < 0.05. RESULT: Of the 43 dogs, 42 completed the study. No statistically significant differences were detected in either physical reactions or changes in cardiorespiratory variables for RR, RB, RE or recovery quality, although RB tended to be higher in group TIA (7/10 versus 1/10 INB and 3/13 IVB).Various cardiorespiratory variables changed overtime within groups. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, all three investigated techniques attenuated responses during rostral rhinoscopy in dogs, although INB and IVB were more efficacious when biopsies were taken.

Ultrasound-guided and 'blind' sciatic nerve injection techniques: Comparison in rat cadavers.

OBJECTIVE: 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. STUDY DESIGN: Prospective, experimental, randomized, cadaveric study. ANIMALS: Adult female Wistar rat cadavers [n = 24, mass 352 g (323-374)]. METHODS: 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. RESULTS: 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. CONCLUSIONS AND CLINICAL RELEVANCE: 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.

Erector spinae plane block in dogs undergoing hemilaminectomy: A prospective randomized clinical trial.

OBJECTIVE: 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. STUDY DESIGN: Prospective randomized clinical trial. ANIMALS: A total of 60 client-owned dogs. METHODS: 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. RESULTS: 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. CONCLUSIONS AND CLINICAL RELEVANCE: The ESP block resulted in a reduced intraoperative opioid consumption compared with the control positive and negative groups.

Cadaveric study of the ultrasound-guided erector spinae plane block over the transverse process of the twelfth thoracic vertebra in dogs: Transversal vs longitudinal approach.

This study describes a transversal (TV) ultrasound-guided erector spinae plane (ESP) block technique over the transverse process of T12. And evaluates the distribution of the dye and affected nerves branches compared to a longitudinal (LNG) approach over the transverse process of T12 in canine cadavers. Secondly, it also compares de anatomy and dimensions of the transverse processes of T12 with T9 and T5. For this double-masked, cadaveric experimental study, 12 adult Beagle cadavers were injected with 0.6 mL/kg of dye/contrast. Spread was evaluated by computed tomography (CT) and dissection. Mean bodyweight was 9.76 (±0.59) kg. The TV and LNG approaches stained a median (range) of four (2-6) and three (1-6) medial branches of the dorsal rami of the spinal nerves, three (2-6) and three (2-5) lateral branches, and one (0-3) and one (0-4) ventral branches, respectively. Dye was detected in the epidural space in 55.6% and 66.7% of cases for the TV and LNG approaches, respectively (P=0.63). And in the ventral paravertebral compartment in 22.2% and lymphatics in 88.8% in both approaches. There were no statistical differences for the spread. The dorsolateral edge of the transverse process (TP) was not visible with CT at T12. The mean (±SD) length of the TP was significantly shorter at T12 [3.34 (±0.22)] mm, compared to T9 [6.08 (±0.47)] mm and T5 [5.93 (±0.62)] mm (P <0.001). This study showed similar distribution whether using a TV or LNG approach and differences in the anatomy and length of the T12 TP.

Topography and morphometry of the infraorbital and mandibular foramen of the common sloth (Bradypus variegatus) for use in the application of perineural anaesthesia.

A local anaesthetic block performed in cranial and mandibular foramina contributes towards analgesia and the reduction of systemic anaesthesia in procedures in the oral cavity. However, anatomical differences between in wild animals may require adaptations to the anaesthetic and surgical manoeuvres of the head used in domestic animals. With that in mind, we aimed to describe the topography and morphometry of the infraorbital and mandibular foramina in Bradypus variegatus, to support perineural anaesthetic approaches in the cranio-mandibular region of this species. We demonstrated that in B. variegatus there is no significant variability in the morphometric data, allowing access to the studied foramina to occur in a similar way in adult individuals. Finally, we understand that the techniques for the infraorbital and mandibular foramen needed to be adapted due to the anatomical singularities of the species, which culminated in new reference points for more assertive needle positioning.

Perioperative analgesic efficacy of lumbar erector spinae plane block in dogs undergoing hemilaminectomy: a randomized blinded clinical trial.

OBJECTIVE: To evaluate the perioperative analgesic effect of the unilateral lumbar erector spinae plane block (ESPBL) in dogs undergoing hemilaminectomy. STUDY DESIGN: Randomized, blinded clinical study. ANIMALS: A total of 30 client-owned dogs undergoing thoracolumbar or lumbar hemilaminectomy for intervertebral disc extrusion (IVDE). METHODS: Dogs were randomly assigned to receive a unilateral ESPBL, performed either with 0.4 mL kg-1 ropivacaine 0.5% [group ROPI (n = 15)] or with saline solution [CNT group (n = 15)]. Dogs were premedicated intravenously (IV) with acepromazine 5 µg kg-1 and methadone 0.2 mg kg-1, general anaesthesia was induced by administering IV midazolam 0.2 mg kg-1 and propofol to effect and maintained with isoflurane. Fentanyl was administered as rescue analgesia. Bradycardia [heart rate (HR) < 60 beats minute-1] with hypotension was treated with atropine IV. The Short-Form of the Glasgow Composite Pain Scale was used pre- and postoperatively at 1, 2, 4, 8, 12, 16, 20 and 24 hours after extubation, and methadone 0.2 mg kg-1 was administered IV when pain score was ≥ 5/20. HR and end-tidal concentration of isoflurane (Fe'Iso) were compared between groups with anova combined with a Dunnet's post hoc test. Time to the first rescue methadone and total dose of fentanyl (FENtot, µg kg-1 hour-1) and methadone (METtot, mg kg-1) in the first 24 postoperative hours were compared using unpaired Student's t test. Postoperative pain scores were compared with the Mann-Whitney test and atropine administration with a Fisher's exact test; p < 0.05. RESULTS: HR, Fe'Iso, FENtot, METtot and atropine administration were significantly lower in group ROPI compared to CNT. Postoperative analgesic effect was significantly longer, and pain scores were significantly lower in group ROPI for all time points. CONCLUSIONS AND CLINICAL RELEVANCE: Unilateral ESPBL with ropivacaine reduced perioperative opioid consumption and the occurrence of bradycardia in dogs undergoing hemilaminectomy.

A novel extraoral ultrasound-guided approach for mandibular nerve block in Rahmani sheep.

BACKGROUND: Regional anesthesia is the favored choice in ruminant animals compared to general anesthesia, primarily due to its high safety margin and reduced demand for cost-intensive equipment in addition to its field applicability. Ultrasound-guided nerve block has gained significant attention in the field of veterinary medicine. This study utilized twenty-seven sheep of the native Rahmani breed to both demonstrate and evaluate the effectiveness of the ultrasound guided inferior alveolar nerve block technique. METHODS: The research comprised three phases: Phase 1 involved an anatomical examination of mandibles and sheep heads to locate the mandibular foramen and delineate the mandibular nerve course. Phase 2 included ultrasound-guided injection of methylene blue dye at specific sites along the mandibular nerve in cadaveric sheep heads. In Phase 3, clinical implementation of ultrasound-guided inferior alveolar nerve blocks was conducted in 27 live sheep, assessing efficacy, onset, and duration. RESULTS: Vertical extraoral ultrasound-guided nerve block was achieved successfully in 25 sheep (98%). A preliminary cadaveric study showed good distribution of the injectate at the mandibular nerve site. The mean onset time was 138 ± 18 s, and the mean duration time was 54 ± 4.1 min. Prominent analgesia of the ipsilateral mandible, medial surface of the cheek, and lateral border of the tongue was observed. CONCLUSIONS: Ultrasound-guided mandibular nerve block holds promise as a technique for providing effective and safe anesthesia in sheep undergoing mandibular procedures.

Introducing a novel intraoral mandibular nerve block technique for loco-regional analgesia in camels (Camelus dromedarius): a cadaveric study using computed tomography.

The aim of this study was to introduce a novel intraoral technique for performing mandibular nerve blocks in dromedary camels (Camelus dromedarius). In this study, 18 adult camel skulls of varying ages and breeds were examined to determine the position of the mandibular foramen. Using a Vernier caliper, three dimensions in millimeters were measured: (1) the distance between the mandibular foramen (MF) and the caudal edge of the third molar tooth at the occlusal surface level, (2) the distance between the MF and the rostral edge border of the mandible's ramus (RER) at the occlusal surface level, and (3) the distance between the MF and the ventral margin border of the mandible (VM). The technique was evaluated using five intact camel cadaver heads (n = 5), and a total of ten mandibular nerve blocks were described. An 18-gauge 80-mm Tuohy needle was inserted into the mouth commissure and advanced caudally while injecting a saline-methylene blue solution. The accuracy of the injection was confirmed through the infiltration of the contrast dye into the target area using computed tomography (CT) and post procedural dissection. Anatomical study of the mandibular nerve site was performed to aid the blind insertion of the needle. The findings contribute to the development of veterinary anesthesia techniques and provide anatomical considerations for clinicians performing oral surgeries in sedated camels. The results demonstrated the successful implementation of the intraoral technique, highlighting its efficacy and reliability in achieving local anesthesia for oral surgeries involving the lower jaw and teeth in sedated camels. Further research studies are needed to evaluate the long-term efficacy and safety of the technique and to compare it with existing approaches.

A Feasibility Study for a Novel Trans-infraorbital Canal Approach to the Maxillary Nerve in Pigs (Sus domesticus).

Experimental maxillofacial surgery is commonly performed in pigs; however, locoregional anesthesia of this area has not been described. This study evaluated the feasibility of a novel maxillary nerve block approach. In part I, cadavers were used to determine anatomic landmarks and assess maxillary nerve dye staining by using 0.03 mL kg-1 of a 1:10 mixture of commercial food dye and 0.5% bupivacaine. In part II, 10 additional pig cadavers underwent bilateral ultrasound-guided maxillary nerve blocks by using trans-infraorbital canal needle placement. The maxillary nerve was harvested and scored based on degree of staining (0 and 1, absent or incomplete staining; 2, staining; >1 cm circumferentially). Intracranial and intraconal spread of dye was evaluated. A Kruskal-Wallis test was used to compare infraorbital canal length estimated either externally via landmarks, internally via ultrasound, or actually measured after dissection. In 18 of 20 (90%) injections, successful staining (score = 2) of maxillary nerves was obtained for a nerve length of 2.4 ± 0.3 cm. Two of 20 cases (10%) had inadequate staining (score <2). At dissection of these 2 cases, the needle tip was observed to have collided with an unerupted tooth (third molar). No intracranial or intraconal spread of dye was observed. We detected no statistical differences between the estimated external, estimated internal, or actual dissection methods for measurement of infraorbital canal length (P = 0.3). Ultrasound-guided trans-infraorbital maxillary nerve block in pigs is a feasible technique, warranting further work to evaluate its in vivo efficacy and safety.

Comparison of preoperative retrobulbar bupivacaine and postoperative subcutaneous liposome-encapsulated bupivacaine on postoperative analgesia in dogs undergoing enucleation.

OBJECTIVE: To compare the effectiveness of preoperative bupivacaine inferotemporal retrobulbar blocks to postoperative liposome-encapsulated bupivacaine (Nocita) line blocks for analgesia following enucleation. ANIMALS: 39 client-owned dogs (40 eyes) presenting to the Ophthalmology Service for enucleation. METHODS: Dogs were randomly assigned to receive either a preoperative inferotemporal retrobulbar block with 0.5% bupivacaine or a peri-incisional line block with liposome-encapsulated bupivacaine (Nocita) at closure. Patients underwent unilateral enucleation and were hospitalized for 24 hours after surgery. Pain scores were performed by a masked observer with the Glasgow Composite Measure Pain Scale and the University of Wisconsin Ocular Pain Scale at 0.25, 0.5, 1, 2, 4, 6, 8, and 24 hours following surgery. Intraoperative use of blood pressure and anesthetic support mediations as well as need for rescue pain control were recorded and compared between groups. RESULTS: There was no significant difference in rescue rates between treatment groups. When comparing the use of medical intraoperative heart rate, blood pressure, or anesthetic plane support, there were no significant differences in use between groups. CLINICAL RELEVANCE: Use of preoperative bupivacaine retrobulbar blocks and postoperative Nocita line blocks were equally effective at postoperative pain control with similarly low complication rates.

Ultrasound-guided sciatic nerve block in Wistar rat cadavers: Relevant anatomy and injection distribution.

OBJECTIVE: 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. STUDY DESIGN: Randomized, experimental, assessor-blinded cadaveric study. ANIMALS: A total of 40 adult female Wistar rat cadavers. METHODS: 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. RESULTS: 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). CONCLUSIONS AND CLINICAL RELEVANCE: 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.

Evaluation of frontal and infratrochlear nerve blocks for standing sedated frontonasal sinusotomy in horses.

OBJECTIVE: To determine if targeted blocking of frontal and infratrochlear nerves provided anesthesia for the approach to a frontonasal sinusotomy. STUDY DESIGN: Two part study: Part 1 randomized crossover design; Part 2 proof of concept. ANIMALS: N = 12; six each in Parts 1 and 2. METHODS: Part 1: Each horse had either frontal and infratrochlear nerve blocks or a line block performed with 2% mepivacaine hydrochloride. Mechanical nociceptive thresholds (MNT) were obtained at five sites along a proposed frontonasal sinusotomy prior to injection, and at 10, 60, and 120 min after blocking. After a 4 day washout period, the opposite procedure was performed. Order of procedure and side of face were randomized. MNTs were analyzed using mixed-model ANOVA with p < .05. Part 2: Frontal and infratrochlear nerve blocks were performed followed by creation of a skin/periosteal incision, which was closed at 2 h. Ability to create and suture the incision, and the size of the incision were recorded. RESULTS: For part 1, both line and targeted blocks resulted in at least two times an increase in median MNT values at each of the five sites, as compared to baseline MNT values (p < .0025). In Part 2, incisions could be completed in five of six horses, with median incision size of 6.5 × 5 cm. CONCLUSION: Following frontal and infratrochlear nerve blocks, MNTs were increased along a proposed frontonasal sinusotomy, and skin incisions could be created in the majority of horses. CLINICAL SIGNIFICANCE: Frontal and infratrochlear nerve blocks provide an alternative technique to create a frontonasal sinusotomy.

Investigation of a maxillary nerve block technique in guinea pigs (Cavia porcellus): A cadaveric study comparing two injectate volumes.

OBJECTIVE: To investigate and describe an extraoral approach to perform a maxillary nerve block in guinea pigs. STUDY DESIGN: Prospective, randomized, blinded, descriptive, cadaveric study. ANIMALS: A total of 14 adult guinea pig cadavers. METHODS: Two cadavers were used for anatomic dissection and determination of maxillary nerve block approach. A maxillary nerve block via infraorbital approach was then performed in 12 cadavers. A low volume (0.1 mL) or high volume (0.2 mL) of diluted methylene blue injectate was randomly assigned to the right or left side, with the other volume used for the contralateral side. The maxillary nerve was dissected after each injection by an investigator blinded to injectate volume. The region of dye distribution was identified, and the degree of staining assigned an accuracy score (0-2). Nerve coverage was considered adequate if ≥6 mm of circumferential staining was present. RESULTS: Accuracy evaluation indicated successful dye deposition in 10/12 [2 (0-2), median (range)] injections in the low volume group and 8/12 [2 (1-2)] injections in the high volume group. The majority (79.2%) of injections resulted in adequate nerve staining. There were no statistically significant differences between injectate volumes for accuracy (p = 0.64) or adequacy (p > 0.99) of staining. CONCLUSIONS: The infraorbital approach is a simple and practical method for maxillary nerve blockade in guinea pigs. An injectate volume of 0.1 mL results in adequate maxillary nerve coverage; however, additional studies are needed to assess the efficacy in clinical use.