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.

Comparison of a blind and an ultrasound-guided technique for Retrobulbar anesthesia in dogs undergoing unilateral subconjunctival enucleation.

OBJECTIVE: This study compared the quality of retrobulbar anesthesia using a blind inferior-temporal palpebral approach (ITP) with an ultrasound-guided supratemporal (ST) technique in dogs undergoing unilateral enucleation. ANIMAL STUDIED: Twenty-one client-owned dogs were undergoing enucleation. PROCEDURES: Dogs were randomly assigned to receive ITP (n = 10) or ST (n = 11) with 0.5% ropivacaine at 0.1 mL/cm of neurocranial length. The anesthetist was blinded to the technique. Intraoperative data included cardiopulmonary variables, inhalant anesthetics requirement, and requirement for rescue analgesia (intravenous fentanyl 2.5 mcg/kg). Postoperative data included pain scores, sedation scores, and need for intravenous hydromorphone (0.05 mg/kg). Treatments were compared using Wilcoxon's rank sum test or Fisher's exact test as appropriate. Comparison of variables over time were tested using a mixed effect linear model on rank. Significance was set at p = 0.05. RESULTS: Intraoperative cardiopulmonary variables and inhalant requirements were not different between groups. Dogs receiving ITP required median (interquartile range, IQR) 1.25 (0, 2.5) mcg/kg intraoperative fentanyl while those receiving ST required none (p < 0.01). Intraoperative fentanyl was required in 5/10 and 0/11 of dogs in the ITP and ST groups, respectively (p = 0.01). Postoperative analgesia requirements were not significantly different between groups; 2/10 and 1/10 dogs in the ITP and ST groups, respectively. Sedation score negatively affected pain score (p < 0.01). CONCLUSIONS: The ultrasound-guided ST technique was more effective at decreasing intraoperative opioid requirements than the blind ITP approach in dogs undergoing unilateral enucleation.

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.

Ultrasound-guided caudal quadratus lumborum block combined with the greater ischiatic notch plane block as motor-protective analgesia for the pelvic limb in dogs.

OBJECTIVE: 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. STUDY DESIGN: Descriptive anatomical study and prospective randomized, blinded, experimental crossover trial. ANIMALS: A total of six canine cadavers and six adult Beagle dogs. METHODS: 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. RESULTS: 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. CONCLUSION AND CLINICAL SIGNIFICANCE: 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.

Image analysis comparison of nerve staining with food dye, methylene blue or tissue marker.

OBJECTIVE: Novel locoregional techniques use dye studies to confirm successful nerve targeting. The goal was to objectively quantify and compare nerve staining characteristics of dye mixtures commonly reported in the literature using image analysis software. STUDY DESIGN: Prospective, randomized cadaveric study. METHODS: Thirty-six brachial plexus nerves from unpreserved pig cadavers were randomized into three groups of 12: FD (1:10 mixture of blue food dye and bupivacaine 0.5%), MB (methylene blue 1%) and TM (0.1:10 mixture of blue tissue marker and lidocaine 2%). Nerves were immersed in dye for 1, 15, 30 or 60 minutes (n = 3 each). Images of nerves before immersion (baseline) and at each time point with epineurium intact (superficial staining) and after longitudinal bisection (deep staining) were processed using image analysis software. Color saturation values were divided into quartiles (dark, medium-dark, medium-light or light). Percentage of stained nerve area in each quartile was calculated and compared using two-way anova. RESULTS: Superficially, at minute 1, dark saturation covered 40% of nerve area in FD versus 19% in MB (p = 0.04) and 0% in TM (p < 0.0001). In bisected nerves, dark and medium-dark saturations occurred only in FD; medium-light saturation comprised anywhere from 4% to 22.5% over time in FD versus <1% at any time in MB (p = 1.000; p = 0.343; p = 0.383; p = 0.262). Deep staining was not found in TM at any point. CONCLUSION AND CLINICAL RELEVANCE: Food dye rapidly stains superficial and deep nerve layers. Based on these characteristics, investigators can choose the appropriate dye for their study.

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.

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.

A comparison of the motor effects and analgesic efficacy following lumbar plexus block combined with sciatic nerve block or epidural in dogs undergoing tibial plateau leveling osteotomy.

OBJECTIVE: To compare motor effects and analgesic efficacy following an ultrasound-guided lateral approach to lumbar plexus blockade at L7 and sciatic nerve blockade (LPSNB) against epidural injection in dogs undergoing tibial plateau leveling osteotomy (TPLO). STUDY DESIGN: Prospective, randomized, blinded clinical trial. ANIMALS: A total of 27 healthy adult dogs undergoing unilateral TPLO surgery. METHODS: Dogs were allocated to either LPSNB (bupivacaine 2 mg kg-1, 0.75%) or epidural (morphine PF 0.1 mg kg-1 and bupivacaine 0.5 mg kg-1, 0.75%). Other aspects of clinical management were identical, including anesthetic drug protocol, area of presurgical clipping and bladder care. Time to perform the block, response to surgical stimuli, pain scores, rescue analgesia, time to stand and walk, motor score and time to first urination were recorded. One evaluator, unaware of treatment status, performed all evaluations. Student's t-test or Mann-Whitney U test was used to compare continuous variables between groups, and Fisher's exact test for categorical variables. RESULTS: Median (range) times to stand and walk were shorter for LPSNB [60 (40-120) minutes and 90 (60-150) minutes, respectively, p = 0.003] than for epidural [150 (120-240) minutes and 180 (120-360) minutes, respectively, p = 0.006]. Four dogs required rescue intraoperatively (three in epidural group, one in LPSNB group, p = 0.438). Pain scores over the 24 hour evaluation period were similar, and not significantly different, for each group. Time to spontaneous urination [LPSNB, 330 (240-360) minutes; epidural, 300 (120-1440) minutes, p = 1.0] did not differ between groups. CONCLUSIONS AND CLINICAL RELEVANCE: An ultrasound-guided lateral paravertebral approach to the lumbar plexus within the psoas compartment at L7, combined with sciatic nerve blockade, allows faster return to normal motor function, with similar pain control and impact on urination when compared with epidural in dogs after TPLO surgery.

Unexpected diagnosis of canine lymphoma when performing an ultrasound-guided cystocentesis on a 3-year-old Rottweiler dog.

A 3-year-old spayed female Rottweiler dog was brought to a veterinary clinic because of weakness, lethargy, and hair coat changes. Hematology and clinical chemistry assessments revealed anemia, hypoalbuminemia, hyperglobulinemia, and hypothyroid. After persistent pyuria, an ultrasound-guided cystocentesis was completed, which revealed a large abdominal mass. A presumptive diagnosis of canine lymphoma with renal spread was made. Due to a poor prognosis, the dog was euthanized.

Diagnostic inattendu de lymphome canin lors de la réalisation d'une cystocentèse échoguidée sur un chien Rottweiler de 3 ans. Une chienne Rottweiler stérilisée de 3 ans a été amenée dans une clinique vétérinaire en raison de faiblesse, de léthargie et de changements de pelage. Les évaluations hématologiques et chimiques cliniques ont révélé une anémie, une hypoalbuminémie, une hyperglobulinémie et une hypothyroïdie. Après une pyurie persistante, une cystocentèse échoguidée a été réalisée, révélant une masse abdominale volumineuse. Un diagnostic présomptif de lymphome canin à propagation rénale a été posé. En raison d'un mauvais pronostic, le chien a été euthanasié.(Traduit par Dr Serge Messier).

Cardiovascular changes, laboratory findings and pain scores in calves undergoing ultrasonography-guided bilateral rectus sheath block before herniorrhaphy: a prospective randomized clinical trial.

BACKGROUND: The study aimed to assess the clinical utility of a multiparametric approach to measure the impact of bilateral ultrasound-guided rectus sheath blocks (RSB) on heart rate, serum cortisol concentrations, and pain in calves undergoing herniorraphy. Fourteen calves were randomly assigned to receive either the RSB (RSB group, n = 7, injected with 0.3 mL/kg of bupivacaine 0.25% and 0.15 µg/kg of dexmedetomidine per side) or a sham injection (CG group, n = 7, injected with an equivalent volume of sterile saline solution). Monitoring included (i) continuous Holter recording from 120 min pre-surgery to 120 min post-surgery; (ii) serum cortisol concentration (SC) at -150 min pre-surgery (baseline), induction time, skin incision, end of surgical procedure (EP-t), and then 30 min, 45 min, 60 min, 120 min, 360 min after recovery; (iii) UNESP-Botucatu pain evaluation at -150 min pre-surgery and 30 min, 45 min, 60 min, 120 min, 240 min, 360 min after recovery. RESULTS: A significant difference in the heart rate was observed within the RSB group, in the time frame between 120 min to induction compared to the time frame between induction to EP-t period. The SC concentration was significantly higher in the CG at the skin incision. Calves in the RSB group recorded significantly lower pain scores at 45 min, 60 min, 120 and 240 min after recovery. CONCLUSIONS: The study demonstrated that monitoring heart rate and serum cortisol concentrations effectively quantified the effects of RSB during surgery. At the same time, the UNESP-Botucatu pain scale identified effects post-surgery when the calves regained consciousness. Overall, ultrasound-guided RSB appeared to enhance the well-being of calves undergoing herniorrhaphy.

Transvaginal ultrasound-guided oocyte retrieval in cattle: State-of-the-art and its impact on the in vitro fertilization embryo production outcome.

Transvaginal ultrasound-guided oocyte retrieval (commonly called OPU) and in vitro embryo production (IVP) in cattle has shown significant progress in recent years, in part, as a result of a better understanding of the full potential of these tools by end users. The combination of OPU and IVP (OPU-IVP) has been successfully and widely commercially used worldwide. The main advantages are a greater number of embryos and pregnancies per unit of time, faster genetic progress due to donor quick turn around and more elite sires mating combinations, larger spectrum of female age (calves, prepuberal, heifer, cow) and condition (open, pregnant) from which to retrieve oocytes, a reduced number of sperm (even sexed) required to fertilize the oocytes, among other benefits. OPU-IVP requires significant less donor preparation in comparison to conventional embryo transfer (<50% of usual FSH injections needed) to the extent of no stimulating hormones (FSH) are necessary. Donor synchronization, stimulation, OPU technique, oocyte competence, embryo performance, and its impact on cryopreservation and pregnancy are discussed.

Administration of carbetocin-a long-acting oxytocin analogue-before sperm collection by transrectal ultrasound-guided massage of the accessory sex glands in bucks (Capra hircus) and ibexes (Capra pyrenaica).

Transrectal ultrasonic-guided massage of the accessory sex glands (TUMASG) is a technique that allows collecting semen requiring few electrical stimuli or even no pulse. A long-acting analogue of oxytocin (carbetocin, 0.1 mg) was i.v. administered before TUMASG in 10 conscious bucks (Experiment 1) and 10 anaesthetized Iberian ibexes (Experiment 2) to shorten the time of semen collection, decrease the number of electrical stimuli and/or improve the semen quality. The ejaculated volume, concentration, quality parameters and kinetics variables of the sperm were determined in fresh semen. The time length of the procedures and the number of electric pulses applied were recorded. Furthermore, stress response indicators (number of vocalizations in Experiment 1; heart and respiratory rates, rectal temperature, cortisol levels, totals proteins and neutrophil-to-lymphocyte ratio in Experiment 2) were documented. In bucks, the administration of carbetocin tended to shorten the time needed for semen collection but no-showed differences in the fresh seminal quality. In the Iberian ibexes, there were no significant differences between groups in the time length of procedures or in the number of animals that ejaculated. Carbetocin administration only reduced the respiratory rate, did it modify fresh semen characteristics in ibexes. In conclusion, the administration of carbetocin did not appear as a useful tool to improve welfare during semen collection with TUMASG or semen quality in conscious bucks and anaesthetized ibexes, having only slight advantages related to the procedure.

Safety and accuracy of blind vs. ultrasound-guided dorsal retrobulbar nerve blocks in horses-A cadaveric study.

OBJECTIVE: There is limited knowledge regarding the safety and accuracy of ultrasound-guided retrobulbar nerve blocks in horses. The aim of this study was to compare these parameters between blind and ultrasound-guided injection techniques for the dorsal retrobulbar nerve block in horses. METHODS: Equine cadaver heads were used to inject the retrobulbar space with contrast medium (CM). Injections were performed either blindly based on anatomic landmarks (blind group, n = 44) or under ultrasonographic guidance (US-group, n = 44), equally divided between an experienced and unexperienced operator. Needle position and distribution of CM were assessed with computed tomography imaging and evaluated by a board-certified veterinary diagnostic imager blinded to the technique. Safety and accuracy of both techniques were compared. RESULTS: Ocular penetration was observed in two cases (n = 2/44) in the blind group but not in the US group (n = 0/44). No intrathecal, intraneural, or intravascular injections were seen in either group. Safety was significantly improved in the US group (p = .026). There was no statistically significant difference between the groups regarding the accuracy of the injection. Excellent accuracy was achieved more often with the ultrasound-guided technique (n = 11/22) than with the blind technique (n = 7/22) when performed by the unexperienced operator, but this difference was not statistically significant. CONCLUSION: To prevent globe-threatening complications and improve the safety of the injection, we recommend using the ultrasound-guided injection technique for the dorsal retrobulbar nerve block.

Surgical description and outcome of ultrasound-guided minimally invasive parathyroidectomy in 50 dogs with primary hyperparathyroidism.

OBJECTIVE: To describe the surgical technique and clinical outcome of minimally invasive parathyroidectomy for primary hyperparathyroidism (PHPT) in the dog. ANIMALS: Fifty client-owned dogs with PHPT that underwent minimally invasive parathyroidectomy. STUDY DESIGN: Retrospective cohort study. METHODS: An ultrasound-guided mini lateral approach was made via a plane established between the sternocephalicus muscle and sternohyoideus muscles to expose the thyroid gland and enlarged parathyroid gland. Abnormal parathyroid glands were removed en bloc via partial thyroidectomy. The technique for bilateral disease was similar, the skin incision was made on midline and moved laterally to develop the above-mentioned plane of dissection. Age, sex, breed, bodyweight, ultrasound findings, histopathological diagnosis, surgical time, preoperative clinical signs, and clinical outcome were extracted from the records for descriptive statistics. RESULTS: A total of 62 glands were surgically removed, including 17 hyperplastic glands (17/62, 27.4%), 34 adenomas (34/62, 54.8%), and two carcinomas (2/62, 3.2%). Hypercalcemia resolved shortly after surgery in 44 dogs (44/45, 97.8%). One dog had recurrent hypercalcemia (1/45, 2.2%), one dog had persistent hypercalcemia (1/45, 2.2%), two dogs had permanent hypocalcemia requiring life-long calcitriol supplementation (2/45, 4.4%), and one dog died from clinical hypocalcemia (1/45, 2.2%). CONCLUSION: Minimally invasive parathyroidectomy was associated with a low morbidity and led to favorable outcomes in 44/45 dogs in this series. CLINICAL SIGNIFICANCE: The results of this study supports the use of minimally invasive parathyroidectomy to treat PHPT in dogs.

Ultrasound-guided lateral pericapsular hip desensitization of the articular branches of the cranial gluteal nerve: A canine cadaveric study and feasibility study in dogs.

OBJECTIVE: To develop and assess the feasibility, as a diagnostic block, of an ultrasound-guided lateral pericapsular hip desensitization (L-PHD) technique in dogs. STUDY DESIGN: Prospective, randomized, anatomical and feasibility study. ANIMALS: A total of 11 canine cadavers and eight adult dogs scheduled for acetabular surgical denervation. METHODS: 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 (LL-PHD group) or medial (LM-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 LM-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. RESULTS: The ultrasound-guided LL-PHD and LM-PHD could be performed by inserting the needle lateral and medial to the deep gluteal muscle. Ultrasound-guided LL-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 LM-PHD selectively stained the articular branches of the cranial gluteal nerve in all but one cadaver. The PPV for LM-PHD successful test prediction was 85.7% (95% confidence interval: 48.6% to 98.6%). CONCLUSIONS: and clinical significance Ultrasound-guided LM-PHD using 0.05 mL kg-1 of dye selectively stained the articular branches of the cranial gluteal nerve in canine cadavers. The LM-PHD technique is feasible and could be used as a diagnostic block before acetabular surgical denervation in dogs.

Lumbosacral plexus block using a combination of ultrasound-guided lateral pre-iliac and parasacral approaches in cats.

OBJECTIVE: 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). STUDY DESIGN: Experimental uncontrolled, anatomic and retrospective cohort study. ANIMALS: A group of eight feline cadavers and 52 medical records. METHODS: 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. RESULTS: 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. CONCLUSIONS AND CLINICAL RELEVANCE: 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.

Antinociceptive effects of bupivacaine injected within the internal abdominis rectus sheath in standing healthy horses.

OBJECTIVE: To evaluate a regional anesthetic technique for blocking the abdominal midline in horses. STUDY DESIGN: Anatomical description and prospective, crossover, placebo-controlled, blinded study. ANIMALS: Adult horses; two cadavers, six healthy animals. METHODS: In stage 1, 0.5% methylene blue with 0.25% bupivacaine (0.5 mL kg-1) was injected using ultrasonography into the internal rectus abdominis sheath (RAS) of two cadavers with a one-point or two-point technique. The dye spread was described after the dissection of the abdomens. In stage 2, each horse was injected with 1 mL kg-1 of 0.9% NaCl (treatment PT) or 0.2% bupivacaine (treatment BT) using a two-point technique. The abdominal midline mechanical nociceptive threshold (MNT) was measured with a 1 mm blunted probe tip and results analyzed with mixed-effect anova. Signs of pelvic limb weakness were recorded. RESULTS: The cadaver dissections showed staining of the ventral branches from the eleventh thoracic (T11) to the second lumbar (L2) nerve with the one-point technique and T9-L2 with the two-point technique. Baseline MNTs were, mean ± standard deviation, 12.6 ± 1.6 N and 12.4 ± 2.4 N in treatments PT and BT, respectively. MNT increased to 18.9 ± 5.8 N (p = 0.010) at 30 minutes, and MNT was between 9.4 ± 2.0 and 15.3 ± 3.4 N from 1 to 8 hours (p > 0.521) in treatment PT. MNTs in treatment BT were 21.1 ± 5.9 to 25.0 ± 0.1 N from 30 minutes to 8 hours (p < 0.001). MNTs after the RAS injections were higher in treatment BT than PT (p = 0.007). No pelvic limb weakness was observed. CONCLUSIONS AND CLINICAL RELEVANCE: Antinociception of at least 8 hours without pelvic limb weakness was observed in the abdominal midline in standing horses after the RAS block. Further investigations are necessary to evaluate suitability for ventral celiotomies.

A non-inferiority study comparing the ultrasound-guided parasacral with a novel greater ischiatic notch plane approach in canine cadavers.

OBJECTIVE: 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. STUDY DESIGN: Prospective, randomized, non-inferiority experimental anatomic study. ANIMALS: A total of 17 (23.9 ± 5.2 kg) mesocephalic canine cadavers. METHODS: 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. RESULTS: 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. CONCLUSIONS AND CLINICAL RELEVANCE: 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.

Effect of needle gauge on pain and specimen quality of ultrasound-guided fine needle sampling without aspiration of the canine spleen.

Modifications of splenic parenchyma are common ultrasonographic findings in dogs. Splenic fine needle aspiration (FNA) is a rapid, safe procedure, routinely performed in veterinary institutions. However, 22-gauge (G) needle usually reported is selected according to general practice and the most appropriate needle size to be used remains unclear. The aim of this prospective, single-center, methods comparison study was to assess the effect of needle size on cytologic specimens' evaluation and animal welfare during the procedure. Dogs underwent ultrasound-guided splenic FNA using 23, 25, and 27G needles. Needles were compared based on initial and then detailed cytologic evaluation. The initial evaluation assessed overall cellularity, cell preservation, hemodilution, and detailed cytologic evaluation referred to exhaustive splenic components. Welfare evaluation was performed based on a scoring system. A total of 54 dogs were included in this study with 54 of 54 welfare evaluations and 35 of 54 cytologic evaluations by one or two European College of Veterinary Clinical Pathology-certified cytologists. The final cytologic diagnosis was unchanged regardless of the needle size. For the initial evaluation, 23G needles provided significantly higher cellularity than the 27G needles. For detailed cytologic evaluation, only the richness in mesothelial cells and stroma was affected by needle size. Pain induced by the procedures was considered low using 23, 25, and 27G needles with the 27G needle producing the least adverse reactions. Findings from the current study supported using needle gauges smaller than the previously published standard 22G needle for spleen ultrasound-guided fine needle nonaspiration in dogs. Due to higher cellularity and lower pain scores, authors recommend the use of 23G needles with a nonaspiration technique.

Contrast administration via ultrasound-guided injection of the cranial tibial artery results in contrast enhancement of the soft tissues of the metatarsus in horses undergoing CT.

Delivery of mesenchymal stem cells (MSC) via intravascular techniques to treat diffuse and/or inaccessible soft tissue injuries has grown in popularity. The purpose of the current prospective, analytical pilot study was to utilize CT to validate this novel technique and provide additional evidence to support its use for injectate delivery to specific soft tissue structures. Of particular interest was the proximal suspensory ligament, which presents a challenging injection target. Six adult horses without lameness underwent CT of the distal hindlimbs. Scans were obtained prior to ultrasound-guided catheterization of the cranial tibial artery, in addition to early and delayed scans acquired following intra-arterial contrast administration. Region of interest analysis of the superficial and deep digital flexor tendons and suspensory ligament was used to assess contrast enhancement within these structures. Linear mixed models were used to determine statistical significance. Significant (P < 0.05) mean contrast enhancement was seen in all postinjection time points in all soft tissue structures of interest. This indicates that ultrasound-guided injection of the cranial tibial artery results in perfusion of injectate throughout the distal hind limb, including the major soft tissue structures of the metatarsus. This provides further support for this technique as a method of MSC delivery to multifocal or inaccessible injury of these structures, including the proximal suspensory ligament.