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To compare static compliance of the respiratory system (C stRS) and the ratio of partial pressure of end-tidal to arterial carbon dioxide (P e′ CO 2 /PaCO 2), in healthy dogs using two approaches for tidal volume (V T) selection during volume-controlled ventilation: body mass based and driving pressure (ΔPaw) guided. Randomized, nonblinded, crossover, clinical trial. A total of 19 client-owned dogs anesthetized for castration and ovariohysterectomy. After a stable 10 minute baseline, each dog was mechanically ventilated with a V T selection strategy, randomized to a constant V T of 15 mL kg–1 of actual body mass (V TBW) or ΔPaw-guided V T (V TΔP) of 7–8 cmH 2 O. Both strategies used an inspiratory time of 1 second, 20% end-inspiratory pause, 4 cmH 2 O positive end-expiratory pressure and fraction of inspired oxygen of 0.4. Respiratory frequency was adjusted to maintain P e′ CO 2 between 35 and 40 mmHg. Respiratory mechanics, arterial blood gases and P e′ CO 2 /PaCO 2 were assessed. Continuous variables are presented as mean ± SD or median (interquartile range; quartiles 1–3), depending on distribution, and compared with Wilcoxon signed-rank tests. The V T was significantly higher in dogs ventilated with V TΔP than with V TBW strategy (17.20 ± 4.04 versus 15.03 ± 0.60 mL kg–1, p = 0.036). C stRS was significantly higher with V TΔP than with V TBW strategy [2.47 (1.86–2.86) versus 2.25 (1.79–2.58) mL cmH 2 O−1 kg–1, p = 0.011]. There were no differences in P e′ CO 2 /PaCO 2 between V TΔP and V TBW strategies (0.94 ± 0.06 versus 0.92 ± 0.06, p = 0.094). No discernible difference in ΔPaw was noted between the strategies. While no apparent difference was observed in the P e′ CO 2 /PaCO 2 between the V T selection strategies employed, C stRS significantly increased during the V TΔP approach. A future trial should explore if V TΔP improves perioperative gas exchange and prevents lung damage. [ABSTRACT FROM AUTHOR]

To evaluate the evidence of analgesic efficacy of tramadol for the management of postoperative pain and the presence of associated adverse events in dogs. A comprehensive search using PubMed/MEDLINE, LILACS, Google Scholar and CAB databases with no restrictions on language and following a prespecified protocol was performed from June 2019 to July 2020. Included were randomized controlled trials (RCTs) performed in dogs that had undergone general anesthesia for any type of surgery. Two authors independently classified the studies, extracted data and assessed their risk of bias using Cochrane's tool. RevMan and GRADE methods were used to rate the certainty of evidence (CoE). Overall 26 RCTs involving 848 dogs were included. Tramadol administration probably results in a lower need for rescue analgesia versus no treatment or placebo [moderate CoE; relative risk (RR): 0.47; 95% confidence interval (CI): 0.26–0.85; I2 = 0%], and may result in a lower need for rescue analgesia versus buprenorphine (low CoE; RR: 0.50; 95% CI: 0.20–1.24), codeine (low CoE; RR: 0.75; 95% CI: 0.16–3.41) and nalbuphine (low CoE; RR: 0.05; 95% CI: 0.00–0.72). However, tramadol administration may result in an increased requirement for rescue analgesia versus methadone (low CoE; RR: 3.45; 95% CI: 0.66–18.08; I2 = 43%) and COX inhibitors (low CoE; RR: 2.27; 95% CI: 0.68–7.60; I2 = 45%). Compared with multimodal therapy, tramadol administration may make minimal to no difference in the requirement for rescue analgesia (low CoE; RR: 1.12; 95% CI: 0.48–2.60; I2 = 0%). Adverse events were inconsistently reported and the CoE was very low. The overall CoE of the analgesic efficacy of tramadol for postoperative pain management in dogs was low or very low, and the main reasons for downgrading the evidence were risk of bias and imprecision. [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]

Genome editing in pigs for xenotransplantation has seen significant advances in recent years. This study compared three methodologies to generate gene-edited embryos, including co-injection of sperm together with the CRISPR-Cas9 system into oocytes, named ICSI-MGE (mediated gene editing); microinjection of CRISPR-Cas9 components into oocytes followed by in vitro fertilization (IVF), and microinjection of in vivo fertilized zygotes with the CRISPR-Cas9 system. Our goal was to knock-out (KO) porcine genes involved in the biosynthesis of xenoantigens responsible for the hyperacute rejection of interspecific xenografts, namely GGTA1, CMAH, and β4GalNT2. Additionally, we attempted to KO the growth hormone receptor (GHR) gene with the aim of limiting the growth of porcine organs to a size that is physiologically suitable for human transplantation. Embryo development, pregnancy, and gene editing rates were evaluated. We found an efficient mutation of the GGTA1 gene following ICSI-MGE, comparable to the results obtained through the microinjection of oocytes followed by IVF. ICSI-MGE also showed higher rates of biallelic mutations compared to the other techniques. Five healthy piglets were born from in vivo- derived embryos, all of them exhibiting biallelic mutations in the GGTA1 gene, with three displaying mutations in the GHR gene. No mutations were observed in the CMAH and β4GalNT2 genes. In conclusion, in vitro methodologies showed high rates of gene-edited embryos. Specifically, ICSI-MGE proved to be an efficient technique for obtaining homozygous biallelic mutated embryos. Lastly, only live births were obtained from in vivo -derived embryos showing efficient multiple gene editing for GGTA1 and GHR. • A comparison of three methodologies based on the introduction of CRISPR-Cas9 complex before (IVF), during (ICSI-MGE), and after fertilization (in vivo) for the production of genetically edited pigs was performed. • ICSI mediated gene editing proved to be an efficient technique for obtaining homozygous biallelic mutated pig embryos, similar to the microinjection of oocytes followed by IVF. • Live births were obtained from in vivo -derived embryos showing efficient multiple gene editing for GGTA1 and GHR genes. [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 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]

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 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 a lateral ultrasound (US)-guided approach to the radial, ulnar, median and musculocutaneous (RUMM) nerves through a single proximal in-plane insertion in cats and to determine whether one or two injection points are required to successfully stain all the target nerves. Prospective study. A total of eight client-owned healthy cats and 12 cat cadavers. In live cats, the US anatomy of the brachium, the landmarks and the site for needle accesses were determined. Then, 12 thawed feline cadavers were used to assess the spread of dye solution and nerve staining following the US-guided proximal-lateral-humeral RUMM injection using one and two injection points. Each cadaver was injected with 0.15 mL kg–1 of a 0.25% new methylene blue solution in either a single injection aimed for the radial nerve of one limb (G1) or via two sites delivering 0.1 mL kg–1 and 0.05 mL kg–1 aimed for the radial and musculocutaneous nerves of the opposite limb, respectively (G2). Upon dissection, staining of the target nerves around their circumference for length of >1 cm was considered successful. Sonoanatomy was consistent with anatomy upon dissection and target nerves were identified in all cadavers. Staining was 100% successful for the radial, median and ulnar nerves in both groups, and 41.7% and 100% for the musculocutaneous nerve in G1 and G2, respectively. This novel lateral US-guided approach for the proximal RUMM nerve block allowed a good identification of the nerves and related structures, and it provided a consistent muscular structure through which the needle could be easily guided. An injection performed in two aliquots (within the caudal and cranial compartments of the neurovascular sheath) appeared to be necessary to successfully stain all the target nerves. [ABSTRACT FROM AUTHOR]

Objective To determine if a nerve stimulation test ( NST) could act as a monitoring technique to confirm sacrococcygeal epidural needle placement in cats. Study design Prospective experimental trial in a clinical setting. Animals Twenty-four adult cats, scheduled for a therapeutic procedure where epidural anesthesia was indicated. Methods Under general anesthesia, an insulated needle was inserted through the S3-Cd1 intervertebral space guided by the application of a fixed electrical current (0.7 mA) until a motor response was obtained. The NST was considered positive when the epidural nerve stimulation produced a motor response of the muscles of the tail, whereas it was considered negative when no motor response was evoked. In the NST positive cases, 0.3 mL kg−1 of 0.5% bupivacaine was administrated before needle withdrawal. Ten minutes after injection, epidural blockade was confirmed by the loss of perineal (anal), and pelvic limbs reflexes (patellar and withdrawal). Results The use of a fixed electrical stimulation current of 0.7 mA resulted in correct prediction of sacrococcygeal epidural injection, corroborated by post bupivacaine loss of perineal and pelvic limb reflexes, in 95.8% of the cases. Conclusion and clinical relevance This study demonstrates the feasibility of using, in a clinical setting, an electrical stimulation test as an objective and in real-time method to confirm sacrococcygeal epidural needle placement in cats. [ABSTRACT FROM AUTHOR]

Objective To determine the minimal electrical threshold (MET) necessary to elicit appropriate muscle contraction when the tip of an insulated needle is positioned epidurally or intrathecally at the Lsub5-6 intervertebral space (phase-I) and to determine whether the application of a fixed electrical current during its advancement could indicate needle entry into the intrathecal space (phase-II) in dogs. Study design Prospective, blinded study. Animals Thirteen (phase-I) and seventeen (phase- II) dogs, scheduled for a surgical procedure where Lsub5-6 intrathecal administration was indicated. Methods Under general anesthesia, an insulated needle was first inserted into the L5-6 epidural space and secondly into the intrathecal space and the MET necessary to obtain a muscular contraction of the pelvic limb or tail at each site was determined (phase- I). Under similar conditions, in dogs of phase-II an insulated needle was inserted through the L5-6 intervertebral space guided by the use of a fixed electrical current (0.8 mA) until muscular contraction of the pelvic limb or tail was obtained. Intrathecal needle placement was confirmed by either free flow of cerebrospinal fluid (CSF) or myelography. Results The current required to elicit a motor response was significantly lower (p < 0.0001) when the tip of the needle was in the intrathecal space (0.48 ± 0.10 mA) than when it was located epidurally (2.56 ± 0.57). The use of a fixed electrical stimulation current of 0.8 mA resulted in correct prediction of intrathecal injection, corroborated by either free flow of CSF (n = 12) or iohexol distribution pattern (n = 5), in 100% of the cases. Conclusion and clinical relevance Nerve stimulation may be employed as a tool to distinguish epidural from intrathecal insulated needle position at the L5-6 intervertebral space in dogs. This study demonstrates the feasibility of using an electrical stimulation test to confirm intrathecal needle position in dogs. [ABSTRACT FROM AUTHOR]