An extended release local anaesthetic: potential for future use in veterinary surgical patients?

Pain Relief Interventions in Australian Livestock Husbandry: A Review of Animal Welfare and Pain Duration

In veterinary medicine and livestock production, ensuring good animal husbandry is vital for the physical and emotional wellbeing of animals under our care. Pain poses challenges for assessment and mitigation, especially in species unable to express pain overtly. This review examines current pain mitigation interventions in routine husbandry, focuses on the duration of pain after procedures and implications for animal welfare. Pain behaviours have been observed for days or weeks after regular husbandry procedures, and many studies have noted pain-related behaviour persisting until study finalisation, suggesting potential undocumented pain beyond study completion. Current products registered in Australia for pain mitigation in livestock primarily target immediate pain associated with procedures. The future of pain relief in livestock demands longer-acting solutions to address post-procedural pain adequately. Providing pain relief for at least 72 h post surgery is recommended, but current products require retreatment intervals to achieve this, posing practical challenges, especially in livestock. Methods of pain relief provision, such as voluntary consumption of medicated feed, transdermal medication delivery and long-acting formulations offer potential solutions for prolonged pain relief, with research ongoing in these areas. There is a need for further research and development of longer-acting pain relief to ensure optimal welfare of livestock.

Dual-responsive in situ gelling polymer matrix for tunable ketamine general anesthesia in experimental animals

Animal experimentation is a critical part of the drug development process and pharmaceutical research. General anesthesia is one of the most common procedures. Careful administration and dosing of anesthetics ensure animal safety and study success. However, repeated injections are needed to maintain anesthesia, leading to adverse effects. Ketamine, a dissociative anesthetic, is commonly used for inducing anesthesia in animals and suffers from a short half-life requiring repeated dosing. Herein, we report a novel system for controlled anesthesia post-intraperitoneal administration. A polymer solution called "premix" was developed using two stimuli-responsive polymers, Pluronic (PF) and Carbopol (CP). As the premix was mixed with ketamine solution and injected, it underwent in situ gelation, hence controlling ketamine release and anesthesia. The PF and CP concentrations were optimized for the gelation temperature and viscosity upon mixing with the ketamine solution. The optimal premix/ketamine formulation (1.5:1) was liquid at room temperature and gel at physiological conditions with favorable mucoadhesion and rheology. Premix retarded the release of ketamine, translating to tunable anesthesia in vivo. Anesthesia duration and recovery were tunable per ketamine dose with minimal side effects. Therefore, we propose the implementation of PF/CP premix as a vehicle for general anesthesia in animals for optimal duration and effect.

Notoginsenoside R1 attenuates bupivacaine induced neurotoxicity by activating Jak1/Stat3/Mcl1 pathway

Bupivacaine, a common amide local anesthetic, can provide effective analgesia or pain relief but can also cause neurotoxicity, which remains a mounting concern in clinic and animal care. However, the precise underlying mechanisms have not been fully elucidated. A natural compound, notoginsenoside R1 (NG-R1) has been reported to exhibit a neuroprotective role in stress conditions. In this study, we explored the function and mechanism of NG-R1 in alleviating bupivacaine-induced neurotoxicity in mouse hippocampal neuronal (HT-22) and mouse neuroblastoma (Neuro-2a) cell lines. Our results exhibited that NG-R1 treatment can significantly rescue the decline of cell survival induced by bupivacaine. Tunel staining and western blotting showed that NG-R1 could attenuate BPV‑induced cell apoptosis. Besides, we focused on Mcl1 as a potential target as it showed opposite expression tendency in response to NG-R1 and bupivacaine exposure. Mcl1 knockdown blocked the inhibitory effect of NG-R1 on cell apoptosis against bupivacaine treatment. Intriguingly, we found that NG-R1 can upregulate Mcl1 transcription by activating Stat3 and promote its nuclear translocation. In addition, NG-R1 can also promote Jak1 phosphorylation and docking analysis provide a predicted model for interaction between NG-R1 and phosphorylated Jak1. Taken together, our results demonstrated that NG-R1 can attenuate bupivacaine induced neurotoxicity by activating Jak1/Stat3/Mcl1 pathway.

A randomized, blinded, placebo-controlled, prospective clinical study to evaluate the effectiveness of a diluted liposomal-encapsulated bupivacaine suspension in dogs undergoing a ventral midline celiotomy

Objective

To evaluate the effectiveness of a liposomal-encapsulated bupivacaine suspension (LEBS; Nocita), at a 1:5 dilution with 0.9% NaCl, for the reduction of postoperative pain scores and a related reduction in the need for postoperative opioids in dogs undergoing ventral midline celiotomy.

Hypothesis

When infused at a 1:5 dilution, LEBS results in less postoperative pain (as indicated by pain scale scores), and a reduction in postoperative opioids, in dogs undergoing ventral midline celiotomy. The use of LEBS does not affect wound healing when compared to placebo.

Study design

This was a randomized, blinded, prospective clinical trial.

Animals

We studied 40 client-owned dogs undergoing abdominal surgery via a ventral midline celiotomy.

Procedure

Dogs undergoing a ventral midline celiotomy were enrolled and randomly allocated to 1 of 2 groups: those receiving LEBS or a placebo injection protocol into tissue planes during closure. The Glasgow Composite Pain Scale-Short Form (GCPS-SF) was used by an observer blinded to the treatment group to assess patients at 0, 1, 2, 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, and 72 h after extubation. Dogs with a score of ≥ 3 in any single category or ≥ 6 total were given a rescue analgesia. Data were analyzed to compare the number of rescue therapy doses administered between the 2 treatment groups.

Results

Forty dogs completed the study. Dogs that received a diluted LEBS protocol were equally likely to require a rescue therapy as those that received the placebo (0.9% NaCl). There were no significant difference in the pain scores or the total number of opioid injections required between the 2 treatment groups.

Conclusion and clinical relevance

In dogs undergoing ventral midline celiotomy, 1:5 diluted LEBS administration alone should not be considered the sole method of pain relief. Liposomal-encapsulated bupivacaine suspension should be used in conjunction with systemic opioids as part of a multimodal analgesic regime. This multimodal approach would allow a reduction in dose or frequency of opioids, therefore lessening the undesired side effects associated with opioids while also decreasing client costs.

The cost of research: Lasting effects of capture, surgery and muscle biopsy on brown bear (Ursus arctos) movement and physiology

Animal models are a key component of translational medicine, helping transfer scientific findings into practical applications for human health. A fundamental principle of research ethics involves weighing the benefits of the research to society against the burden imposed on the animals used for scientific purposes. The utilisation of wild animals for research requires evaluation of the effects of capture and invasive sampling. Determining the severity and duration of these interventions on the animal's physiology and behaviour allows for refining study methodology and for excluding or accounting for biased data. In this study, 39 Scandinavian brown bears (Ursus arctos) captured either while hibernating in winter or via helicopter in summer and that underwent surgery as part of a human health project had their movement, body temperature and timing of onset of hibernation compared with those of 14 control bears that had not been captured during the same period. Bears captured in winter and summer showed decreased movement from den exit until late summer, compared to those in the control group. Bears captured in summer showed reduced movement and body temperature for at least, respectively, 14 and 3 days, with an 11% decrease in hourly distance, compared to pre-capture levels, but did not differ in the timing of hibernation onset. We reveal that brown bear behaviour and physiology can be altered in response to capture and surgery for days to months, post-capture. This has broad implications for the conclusions of wildlife studies that rely upon invasive sampling.

Anaesthesia in Veterinary Oncology: The Effects of Surgery, Volatile and Intravenous Anaesthetics on the Immune System and Tumour Spread

Throughout the course of oncological disease, the majority of patients require surgical, anaesthetic and analgesic intervention. However, during the perioperative period, anaesthetic agents and techniques, surgical tissue trauma, adjuvant drugs for local pain and inflammation and other non-pharmacological factors, such as blood transfusions, hydration, temperature and nutrition, may influence the prognosis of the disease. These factors significantly impact the oncologic patient's immune response, which is the primary barrier to tumour progress, promoting a window of vulnerability for its dissemination and recurrence. More research is required to ascertain which anaesthetics and techniques have immunoprotective and anti-tumour effects, which will contribute to developing novel anaesthetic strategies in veterinary medicine.

Effects of subconjunctival ropivacaine, liposomal bupivacaine, and mepivacaine on corneal sensitivity in healthy horses

OBJECTIVE

To evaluate corneal sensitivity and adverse events following subconjunctival administration of three local anesthetics in horses.

STUDY DESIGN

Randomized, masked, crossover study.

ANIMALS

Twelve healthy adult mares.

METHODS

The subconjunctival space of the treated eye was injected with 0.2 mL of liposomal bupivacaine (1.3%), ropivacaine (0.5%), or mepivacaine (2%). All horses received each medication once and the contralateral eye received saline (control). Corneal touch threshold (CTT) was measured using a Cochet-Bonnet esthesiometer before sedation, after sedation, and at specified intervals until it returned to baseline. Ocular examinations were performed at 24-, 72, and 168 h post-injection to monitor for adverse effects.

RESULTS

The mean total time of anesthesia (TTA) was 168.3 min for ropivacaine, 169.2 min for liposomal bupivacaine, 103.3 min for mepivacaine and 30.7 min for the control. TTA for liposomal bupivacaine (p < .001) and ropivacaine (p = .001) was longer than the control. TTA for mepivacaine was not different from the control (p = .138), liposomal bupivacaine (p = .075) or ropivacaine (p = .150). Injection site hemorrhage reduced TTA regardless of treatments (p = .047). No adverse effects attributed to injections were noted.

CONCLUSION

All three medications were well tolerated. Subconjunctival administration of ropivacaine and liposomal bupivacaine resulted in longer TTAs compared to the control; however, their TTAs were not different from that of mepivacaine.

CLINICAL SIGNIFICANCE

Subconjunctivally administered liposomal bupivacaine and ropivacaine are viable options to provide prolonged corneal analgesia in horses. Future studies are needed to assess the efficacy in diseased eyes.

Nociception in Chicken Embryos, Part I: Analysis of Cardiovascular Responses to a Mechanical Noxious Stimulus

Although it is assumed that chicken embryos acquire the capacity for nociception while developing in the egg, an exact time point has not yet been specified. The present research was an exploratory study aiming to determine when the capacity of nociception emerges during embryonic development in chickens. Changes in blood pressure and heart rate (HR) in response to a noxious mechanical stimulus at the base of the beak versus a light touch on the beak were examined in chicken embryos between embryonic days (EDs) 7 and 18. Mean arterial pressure (MAP) was the most sensitive parameter for assessing cardiovascular responses. Significant changes in MAP in response to a noxious stimulus were detected in embryos at ED16 to ED18, whereas significant changes in HR were observed at ED17 and ED18. Infiltration anesthesia with the local anesthetic lidocaine significantly reduced the response of MAP on ED18, so the measured cardiovascular changes may be interpreted as nociceptive responses.

The Outcomes of an Opioid-Free Anaesthetic Plan in Fourteen Dogs Undergoing Enucleation Using an Ultrasound-Guided Supra-Temporal Retrobulbar Block: A Retrospective Case Series

The objective of this retrospective case series is to report the outcomes of an opioid-free anesthetic plan in dogs undergoing enucleation surgery. A total of 14 dogs were admitted for enucleation between March and December 2020. A multimodal approach to perioperative analgesia was used, with a focus on retrobulbar anesthesia. A combination of an ultrasound-guided retrobulbblock with a supratemporal approach in association with ketamine, dexmedetomidine and non-steroidal anti-inflammatory drugs was used in the reported cases. Intraoperative nociception was defined as an increase of 20% from the baseline in one or more of the following parameters: heart rate, respiratory rate or mean arterial pressure. An ultrasound-guided retrobulbar block in an opioid-free anesthesia regime was effective at managing the perioperative analgesia of 13 out of 14 dogs. In only one case, a bolus of fentanyl was administered to treat intraoperative nociception. Recovery was uneventful in all the dogs, and the postoperative pain scores remained below the intervention threshold at all time points. To the authors' knowledge, this is the first reported case series of opioid-free anesthesia for enucleation in dogs.

Pelvic limb anesthesia and analgesia in dogs undergoing tibial plateau leveling osteotomy (TPLO): A survey of board-certified anesthesiologists

OBJECTIVE

To report the locoregional anesthesia and analgesia preferences of veterinary anesthesiologists for use in dogs undergoing a TPLO and determine any association with specialty college, time from board-certification, or employment sector.

STUDY DESIGN

Cross sectional study.

SAMPLE POPULATION

Diplomates of the American (ACVAA) and European (ECVAA) Colleges of Veterinary Anesthesia and Analgesia.

METHODS

An electronic survey was distributed to diplomates and responses were used to determine associations between preferred methods.

RESULTS

The survey response rate was 28% (141/500) with 69% (97/141) of ACVAA diplomates and 31% of diplomates with ECVAA (44/141) certification. Peripheral nerve block (PNB) was preferred by 79% (111/141) of all diplomates, lumbosacral epidural (LE) by 21% (29/141), and peri-incisional infiltration (PI) by <1% (1/141). There was no association (p = .283) with specialty college. There was an association (p < .001) with time from board-certification with increased preference for LE when >10-years from certification and PI preferred by only those board-certified >20-years ago. There was an association with employment sector (p = .003) with more academic diplomates preferring LE. Anesthesiologists reported that treatment decisions were affected by various factors including time pressure and surgeon influence.

CONCLUSION

Diplomates of ACVAA and ECVAA prefer PNB as the locoregional method of pelvic limb anesthesia in dogs undergoing TPLO. A greater percentage of newer and private practice diplomates prefer PNB while a larger percentage of senior and academic diplomates prefer LE. Decision making is multifactorial and includes perceived time pressure and surgeon influence.

CLINICAL SIGNIFICANCE

Veterinary anesthesiologists prefer and frequently use PNB in dogs undergoing TPLO and surgeon influence may affect their chosen treatment.

Post-operative Pain Assessment Following Tooth Extraction Using Liposomal Encapsulated Bupivacaine as a Local Anesthetic in Dogs

The objective of this study was to evaluate owner assessment of appetite, demeanor, and mouth soreness following dental extractions in dogs receiving either bupivacaine hydrochloride (BH) or liposomal encapsulated bupivacaine (LEB) for dental blocks. Thirty healthy, adult dogs requiring dental extractions were enrolled in the study. All procedures were completed with dogs under general anesthesia. A non-steroidal anti-inflammatory drug was administered subcutaneously in the preoperative period. Dogs were randomly assigned to receive BH or LEB. An owner assessment to evaluate appetite, demeanor, and soreness of mouth was completed at the end of both the first and second day after discharge from the hospital. The total of the owner assessments for day 1 and both days combined was significantly lower for dogs receiving LEB (P = .007). There were no differences in the number of extractions (P = .21), time from block to evaluations (P = .07), in-hospital pain assessments (P = .99), or number of dogs requiring rescue analgesia (P = .99). This study concluded, dogs that received LEB for dental blocks had improved appetite and demeanor, and reduced soreness of mouth, as evaluated by the owner two days postoperatively, when compared to dogs who received BH.

Treatment of Pain in Rats, Mice, and Prairie Dogs

Recent myomorph and scuiromorph rodent analgesia studies are reviewed and evaluated for potential clinical application. Differences between laboratory animal studies and clinical use in diseased animals are discussed. Analgesia classes reviewed include local anesthetics, nonsteroidal anti-inflammatories, acetaminophen, opioids, and adjuvants such as anticonvulsants. Routes of administration including sustained-release mechanisms are discussed, as are reversal agents. Drug interactions are reviewed in the context of beneficial multimodal analgesia as well as potential adverse effects. Dosage recommendations for clinical patients are explored.

Pharmacokinetics and efficacy of a novel long-acting bupivacaine formulation for cornual nerve block in calves

Local anesthetics are commonly used in farm animals to provide analgesia for painful procedures but can cause adverse effects at high systemic concentrations. The pharmacokinetics and efficacy of a long-acting sucrose acetate isobutyrate (SAIB) bupivacaine formulation following cornual nerve block in calves were compared to lidocaine. Fourteen calves were randomly assigned to one of the treatment groups (i) 5% Bupivacaine-SAIB (BUP-SAIB), n = 7; or (ii) 2% lidocaine (LID), n = 7. Cornual nerve block was performed, and duration of effective analgesia was evaluated by nociceptive threshold testing using a hand-held pressure algometer. Blood samples were collected at various time points and plasma concentrations were analyzed by HPLC. Pharmacokinetic parameters were calculated using a non-compartmental model. The mechanical nociceptive thresholds showed that the novel formulation could desensitize the skin around the horn bud for 18.77 ± 8.88 h (range 8–36 h), compared to 0.79 ± 0.34 h (range 0.5–1.5 h) with lidocaine. The mean maximum plasma concentration (Cmax) of bupivacaine was 152.03 (SD 37.34) ng/mL and its Tmax was 0.39 (SD 0.13) h. The half-life of elimination was 32.79 ± 11.00 h and the rate of clearance was 0.12 ± 0.03 L h−1. No toxicity signs were seen after treatment in either group. The novel formulation produced long-lasting analgesia of several times greater duration than that produced by lidocaine. This study showed that the safety and efficacy of the SAIB formulation justifies further studies in a larger population of animals.

Efficacy of Adductor Canal Block on Medial Knee Pain in Patients with Knee Osteoarthritis: A Randomized Single-Blind Placebo-Controlled Study

BACKGROUND

This study aimed to confirm the efficacy of ultrasound-guided adductor canal block (ACB) as a treatment option for medial knee pain caused by knee osteoarthritis (KOA).

METHODS

In total, 31 participants with medial knee pain due to KOA were randomized to either the ACB (ultrasound-guided ACB, n = 15) or placebo group (1 mL of 1% lidocaine, n = 16). The primary outcome was a numerical rating scale (NRS) for knee pain intensity comparing before and 4 weeks after injection. The secondary outcomes were the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), average daily number of analgesics consumed, average daily opioid consumption, and Timed Up and Go (TUG) test results before and 4 weeks after injection.

RESULTS

Participants' baseline characteristics were not significantly different between the groups, except for age. At 4 weeks post-injection, the NRS score in the ACB group significantly improved compared to that in the placebo group (p = 0.009). However, the WOMAC, average daily number of analgesics consumed, average daily opioid consumption, and TUG test results did not show significant differences.

CONCLUSION

ACB can be an effective treatment for reducing medial knee pain in patients with KOA.

Use of Transversus Abdominis Plane and Intercostal Blocks in Bitches Undergoing Laparoscopic Ovariectomy: A Randomized Controlled Trial

In humans and dogs, loco-regional anesthesia is associated with lower peri-operative opioid consumption and less related side effects. The combination of transversus abdominis plane (TAP) and intercostal blocks can be used to desensitize the entire abdominal wall in dogs. The aim of this study was to evaluate the effectiveness of TAP and intercostal blocks in bitches undergoing laparoscopic ovariectomy. Twenty client-owned bitches were enrolled in this double-blinded randomized controlled trial. After premedication with dexmedetomidine, methadone and ketamine, the animals were randomized into two groups. Dogs in the TAP group received intercostal blocks from T8 to T10 and a TAP block with ropivacaine. Dogs in the FEN group received a fentanyl bolus and a constant rate infusion for the entire duration of the procedure. Intra-operative cardiovascular stability, post-operative pain scores, rescue opioid requirement, dysphoria during recovery, time to attain sternal recumbency and interest in food at 6 h post-extubation were compared. Bitches in the TAP group received a statistically significant lower amount of rescue fentanyl intra-operatively and methadone post-operatively. Pain scores were lower in the TAP group until 6 h post-extubation. No difference was found for dysphoric recoveries, time to attain sternal recumbency and appetite at 6 h post-extubation. No adverse event was recorded for any of the dogs. The combination of TAP and intercostal blocks can be part of an effective multi-modal analgesic strategy in bitches undergoing laparoscopic ovariectomy.

Incidence and severity of short-term incisional complications after intraoperative local infiltration of liposomal bupivacaine in dogs

OBJECTIVE

To report the incidence of short-term incisional complications in dogs receiving intraoperative local infiltration of liposomal bupivacaine.

STUDY DESIGN

Retrospective study.

ANIMALS

Client-owned dogs (n = 218).

METHODS

Medical records were searched for dogs whose surgical site was infiltrated with liposomal bupivacaine. Records were reviewed for complications within 20 days postoperatively. Cases were categorized by: (1) surgical wound classification (clean, clean-contaminated, contaminated); (2) labeled versus off-label use in orthopedic surgery - stifle surgery to address cranial cruciate ligament (CCL) disease versus other orthopedic procedures; and (3) orthopedic versus soft-tissue surgery.

RESULTS

Complications were documented in 43/218 (19.7%) records, including 27/218 (12.4%) complications that resolved spontaneously or with topical treatment. The incidence of short-term incisional complications did not differ between surgical wound classifications (P = 0.55) or between labeled versus off-label use in orthopedic surgery (P = 0.21). Complications seemed more common after soft-tissue procedures (32/123; 26.0%) than orthopedic procedures (11/95; 11.6%) (P < 0.01).

CONCLUSION

Surgical wound classification or type of orthopedic procedure did not seem to influence incisional complications of infiltrated surgical sites. Complications were more common after soft-tissue procedures than orthopedic procedures.

CLINICAL SIGNIFICANCE

Infiltration of surgical sites with liposomal bupivacaine seems safe in a broader range of orthopedic procedures than currently labeled. The results also justify further investigation in soft-tissue surgery.

Evaluation of bupivacaine liposome injectable suspension efficacy in single-use vials over five days of multiple use

OBJECTIVE

To test the anesthetic effect of a bupivacaine liposome injectable suspension (BLIS), used in a multiple-dose manner for up to 5 consecutive days.

STUDY DESIGN

Prospective, randomized, experimental study.

ANIMALS

A total of 30 male and female Sprague-Dawley rats (Rattus norvegicus), aged 97 (75-130) days and weighing 337.2 (219.6-465.9) g, mean (range).

METHODS

Rats were assigned to one of five BLIS vial groups, in which drug was administered from a newly opened vial or 1, 2, 3 and 4 days after the vial was opened. The vials were refrigerated between uses. A 14 gauge needle attached to an injection plug was used to puncture each vial once and was not removed; BLIS was withdrawn from the injection plug in a multiple-dose fashion. A dose rate of 0.4 mL kg^-1 was administered subcutaneously into the left pelvic limb paw. Antinociception was evaluated using a paw pressure test on both injected and uninjected paws before (time 0, baseline) and 1, 24, 48 and 72 hours after injection.

RESULTS

Age of BLIS vial had no significant effect on anesthetic efficacy (p = 0.97). Across all groups, paw withdrawal latency averaged 5.23 ± 0.24 seconds at baseline (before BLIS injection), increased to 16.45 ± 0.65 seconds at 1 hour after BLIS injection, declined to 7.50 ± 0.76 seconds at 24 hours after BLIS injection, and further declined thereafter (p < 0.001). There was no significant change in paw withdrawal latency in the uninjected paw over time.

CONCLUSIONS AND CLINICAL RELEVANCE

BLIS single-use vials retained efficacy when used up to 5 days in a multiple-dose fashion. Because anesthetic effects declined substantially after 24 hours, multimodal pain management remains important for providing analgesia care.

Lidocaine and bupivacaine as part of multimodal pain management in a C57BL/6J laparotomy mouse model

While the use of local anesthesia as part of multimodal pain management is common practice in human and veterinarian surgery, these drugs are not applied routinely in rodent surgery. Several recommendations on the use of local anesthesia exist, but systematic studies on their efficacy and side effects are lacking. In the present study, male and female C57BL/6J mice were subjected to a sham vasectomy or a sham embryo transfer, respectively. We tested whether a mixture of subcutaneously injected Lidocaine and Bupivacaine in combination with systemic Paracetamol applied via drinking water results in superior pain relief when compared to treatment with local anesthesia or Paracetamol alone. We applied a combination of methods to assess behavioral, emotional, and physiological changes indicative of pain. Voluntary Paracetamol intake via drinking water reached the target dosage of 200 mg/kg in most animals. Local anesthesia did not lead to obvious side effects such as irregular wound healing or systemic disorders. No relevant sex differences were detected in our study. Sevoflurane anesthesia and surgery affected physiological and behavioral measurements. Surprisingly, Paracetamol treatment alone significantly increased the Mouse Grimace Scale. Taken together, mice treated with a combination of local anesthesia and systemic analgesia did not show fewer signs of post-surgical pain or improved recovery compared to animals treated with either local anesthesia or Paracetamol.

The effect of extracorporeal shockwave on liposomal bupivacaine in a tibial plateau leveling osteotomy model

OBJECTIVE

To determine the effect of extracorporeal shock wave (ESWT) on liposomal bupivacaine in a tibial-plateau-leveling osteotomy model.

STUDY DESIGN

In vitro study.

SAMPLE POPULATION

Ten samples per group.

METHODS

In addition to a control group (sham treatment), five treatment groups were defined as A, energy (E) 3 (0.22 mJ/mm² ), 360 pulses per minute (p/m); B, E6 (0.29 mJ/mm² ), 360 p/m; C, E8 (0.39 mJ/mm² ), 360 p/m; D, E6, 480 p/m; E, E8 480 p/m. Two-milliliter aliquots of liposomal bupivacaine were placed in a gelatin chamber and treated with 1000 pulses according to group. All samples remained in the chamber for 170 seconds to reflect the longest treatment group. Free bupivacaine concentrations were determined after treatment with high-performance liquid chromatography.

RESULTS

The median free bupivacaine concentration was reported as control, 1.90 mg/mL; A, 2.10 mg/mL; B, 2.03 mg/mL; C, 2.94 mg/mL; D, 2.71 mg/mL; E, 4.35 mg/mL. Groups C (P = .027), D (P = .034), and E (P = .002) were different from the control group. Groups C (P = .0025) and D (P = .0025) were different from group E. Additional intertreatment group differences were found.

CONCLUSION

Extracorporeal shock wave therapy caused a dose-dependent release of bupivacaine; however, there was no significant release of bupivacaine from liposomes when ESWT was applied at currently recommended therapeutic settings in this model.

CLINICAL SIGNIFICANCE

This in vitro study provides evidence that concurrent electrohydraulic ESWT and liposomal bupivacaine is likely safe at currently recommended settings, however, higher energy and pulse frequency settings should be avoided.

Local and regional anaesthesia in dogs and cats: Overview of concepts and drugs (Part 1)

Pain management in veterinary patients is a crucial component of appropriate patient care. Multimodal analgesia that includes both systemically and locally/regionally administered drugs is generally the most effective approach to providing pain relief. Local anaesthetic drugs used in local and regional blockade are unique in that they can completely block the transmission of pain (in conscious patients) or nociceptive (in anaesthetized patients) signals, thereby providing profound analgesia. In addition, local and regional administration of drugs, when compared with systemic bolus administration, generally results in a lower incidence of dose‐related adverse effects. Due to the potential to provide profound analgesia and the high safety margin (when used correctly) of this drug class, local anaesthetics are recommended as part of the analgesic protocol in the majority of patients undergoing surgical procedures or suffering traumatic injuries. This manuscript, Part 1 of a two‐part instalment, emphasizes the importance of using local and regional anaesthesia as a component of multimodal analgesia, provides a review of the basic pharmacokinetics/pharmacodynamics of local anaesthetic drugs in general, lists information on commonly used local anaesthetic drugs for local and regional blockade in dogs and cats, and briefly introduces the novel liposome‐encapsulated bupivacaine (NOCITA®). Part 2 is a review of local and regional anaesthetic techniques used in dogs and cats (Grubb & Lobprise, 2020).

Sterility and concentration of liposomal bupivacaine single-use vial when used in a multiple-dose manner

OBJECTIVE

To evaluate the sterility of bupivacaine liposome injectable suspension (Nocita®) used in a multiple-dose fashion for 5 days.

STUDY DESIGN

Triplicate liposomal bupivacaine vials were stored under two conditions, (1) room temperature (24°C) and (2) refrigerated temperature (5°C). A 3-mL aliquot was withdrawn from each vial daily. Samples were inoculated in tryptic soy broth in triplicate and then incubated for 24 hours at 37°C and subcultured every 48 hours onto blood agar and Sabouraud dextrose agar, respectively. Separate 1.5-mL aliquots of liposomal bupivacaine were centrifuged at 3500 g to separate liposome-encapsulated bupivacaine from the solution. Concentration of unencapsulated bupivacaine was analyzed via high-pressure liquid chromatography. Data were analyzed by using mixed effects procedure with multiple comparisons.

SAMPLE POPULATION

Ten 20-mL vials of bupivacaine liposome injectable suspension stored under two conditions, (1) room temperature (24°C) and (2) refrigerated temperature (5°C).

RESULTS

Five days of repeated withdrawal from the single-use vials yielded no bacterial growth. One control vial, which was opened and punctured once on the last day of the experiment, yielded fungal growth of an Aspergillus spp, likely an environmental contaminant. The concentration of free bupivacaine did not significantly differ until the fifth day of sampling.

CONCLUSION

When aseptic technique was used, liposomal bupivacaine remained sterile for 5 days. Concentrations of free bupivacaine were unchanged from baseline for 4 days in both refrigerated and room temperature conditions.

CLINICAL SIGNIFICANCE

Single-use liposomal bupivacaine vials can be used extralabel in a multiple-dose fashion for up to 4 days when stored either refrigerated or room temperature when sterile technique is used.

Locoregional Anesthesia of the Head

Locoregional (local and regional) anesthesia is used routinely during surgical procedures of the head. The goal of this article is to provide a practical guide for the clinician to safely perform different techniques in dogs and cats and to minimize the risk of complications associated with locoregional anesthesia.

Local Anesthetics: Pharmacology and Special Preparations

Local anesthetics are the only class of drugs that can block transduction and transmission of nociception. Physical properties, mechanism of action, and pharmacokinetics of this class of drugs are reviewed in this article. The clinical use, such intravenous administration of lidocaine, and local and systemic toxic effects are covered. A review of current studies published in the human and veterinary literature on lidocaine patches (Lidoderm) and liposomal bupivacaine (Experal and Nocita) are discussed.

The US Opioid Epidemic and Its Impact on US General Practice Veterinarians

Objective: To assess the impact of the human opioid epidemic and associated shortages in drug supply on US general practice veterinarians. Design: Cross-sectional study. Sample: Members of the Veterinary Information Network (VIN). Procedures: An electronic survey was used to examine veterinarians' views regarding opioid use in veterinary medicine and the impact of the opioid shortage on the provision of care. The survey was distributed via the VIN data collection portal from October 12-November 6, 2018. Results: 697 veterinarians completed the survey. Most (99.7%) reported using, dispensing or prescribing opioids in veterinary practice. The most commonly used opioids were buprenorphine, tramadol and butorphanol. While most veterinarians (83.3%) reported difficulty in ordering opioids over the last 6 months, this decreased to 59.0% in the last month. The most difficult drugs to obtain were hydromorphone, morphine, injectable fentanyl, and oxymorphone. The reported rate of difficulty in obtaining all these drugs lessened over time. However, the opioid shortage caused significant difficulty in providing appropriate pain management for 41.1% of participants, and affected the ability of 44.8% of respondents to provide optimal anesthesia. Conclusions and Clinical Relevance: Veterinarians' ability to provide opioids for their patients has been impacted by the opioid shortage, with a greater impact on full mu opioid agonists as compared to drugs like butorphanol, buprenorphine, and tramadol. The results confirm the important role of opioid analgesics in the delivery of modern veterinary medicine and highlight the importance of medical health professionals being able to access these critical medications.

Preliminary Evaluation of Sustained-release Compared with Conventional Formulations of Meloxicam in Sheep (Ovis aries)

Sustained-release (SR) drugs refine current analgesic regimens by alleviating the need for multiple sessions of handling and restraint and by reducing the local tissue irritation that can occur due to repeated injections. Although a variety of SR drugs are already used in lab animal medicine, no studies exist that evaluate the suitability of an SR NSAID in sheep. This study used HPLC-MS to measure the plasma concentrations of 2 formulations of meloxicam-conventional and SRM- after subcutaneous administration in 6 adult ewes. Blood was collected at 0, 4, 12, 24, 36, 48, 60, 72, 84, 96, 120, 144, and 168 h after injection. In addition, physical exams, urinalysis, and biochemical analysis were performed at 0, 24, 48, and 120 h after dosage. Peak plasma concentrations were 1057 ± 433 ng/mL at 4 ± 0 h for conventional meloxicam and 3238 ± 1480 ng/mL at 6.7 ± 4.1 h for SR meloxicam (SRM). Elimination half-lives were 12.1 4.2 for CM and 15.2 ± 2.4 h for SRM. One sheep had an episode of acute renal azotemia starting 24 h after SRM administration; the episode resolved over time, and the definitive relationship to SRM administration was not determined. Plasma levels of SRM were higher than CM throughout the initial 24 h, remained variably elevated until 60 h after injection, but failed to sustain presumed therapeutic levels of 400 ng/mL for the full 72 h across all animals in this study. Further investigation is warranted to determine the safety and clinical efficacy of SRM in sheep. Currently, when SRM is used in sheep, we recommend the combination of a preemptive and multimodal analgesia regimen with clinical assessments throughout the postoperative period.

Ropivacaine regulates the expression and function of heme oxygenase-1

As a new generation of amide-type local anesthetics (LAs), ropivacaine has been widely used for pain management in clinical settings. Increasing evidence has shown that administration of ropivacaine causes cytotoxic effects and apoptosis. However, the underlying molecular mechanisms still need to be elucidated. In the current study, our results indicated that ropivacaine treatment caused a significant induction of heme oxygenase-1 (HO-1) at both the mRNA and protein levels in human SHSY5Y cells. Levels of HO-1 mRNA and protein peaked at 1 h and 18 h, respectively, in response to ropivacaine treatment. Additionally, ropivacaine treatment enhanced HO-1 activity in a dose-dependent manner. Interestingly, we found that ropivacaine treatment induced phosphorylation of p38. Blockage of p38 phosphorylation with its specific inhibitor SB203580 or by transfection with p38 siRNA restrained ropivacaine-stimulated HO-1 expression. Additionally, we found that ropivacaine treatment promoted nuclear translocation of Nrf2 and amplified ARE promoter activity. Silencing of Nrf2 abolished ropivacaine-induced HO-1 expression. Notably, we found that inhibition of HO-1 activity promoted ropivacaine-induced production of reactive oxygen species (ROS), deletion of reduced glutathione (GSH), and release of lactate dehydrogenase (LDH), suggesting that induction of HO-1 by ropivacaine acted as a compensatory survival response against ropivacaine.

Defining local nerve blocks for feline distal pelvic limb surgery: a cadaveric study

Objectives Anatomical and methodological detail is lacking regarding local anesthetic peripheral nerve block techniques for distal pelvic limb surgery in cats. The aim of this study was to develop, describe and test nerve block methods based on cadaveric dissections and dye injections. Methods Ten pairs of feline pelvic limbs (n = 20) were dissected and the tibial nerve (T n.), common fibular (peroneal) nerve (CF n., and its two branches, the superficial fibular [peroneal] nerve [SpF n.] and the deep fibular [peroneal] nerve [DpF n.]) and the saphenous nerve (Sa n.) were identified. Based on these dissections, a 'distal crus block' (selective blockade of the CF n., T n. and Sa n.) and a 'distal pes block' (selective blockade of the SpF n., DpF n., T n. and Sa n.) were developed for surgical procedures in two different regions of the distal pelvic limb. Techniques were tested using new methylene blue (NMB) dye injections in feline pelvic limbs (n = 12). Using a 25 G × 5/8 inch needle and 1 ml syringe, 0.1 ml/kg of NMB dye solution was injected at the site of the CF n., and 0.05 ml/kg was injected at the sites of the SpF n., DpF n., Sa n. and T n. The length and circumference (fully or partially stained) of each stained nerve were measured. Results Positive staining of nerves was observed in 12/12 limbs. The lengths stained for the CF n., DpF n., SpF n., Sa n. and T n. were 27.19 ± 7.13, 20.39 ± 5.57, 22.82 ± 7.13, 30.89 ± 6.99 and 25.16 ± 8.09 mm, respectively. The nerves were fully stained in 12, 12, 10, 11 and 11 out of 12 limbs, respectively. Conclusions and relevance These two, three-point injection methods may be an effective perioperative analgesia technique for feline distal pelvic limb procedures.