The effects of adding epinephrine or xylazine to lidocaine solution for lumbosacral epidural analgesia in fat-tailed sheep

Efficacy of a Lidocaine-Impregnated Elastrator Band for Castration and Tail Docking in Lambs

The primary objective of this study was to demonstrate the non-inferiority between lidocaine-impregnated ligation bands (LLBs) and control bands (CBs) with respect to the efficacy of castration and tail docking. Secondary objectives were to compare castration and tail-docking success, evaluate local site reactions, and compare average daily gain (ADG) between the treatment groups. A total of 238 male lambs were enrolled and randomly assigned to receive LLBs or CBs on their tail and scrotum. Lambs were weighed, had a health assessment, and the band site was observed on -3, 7, 14, 21, 28, 35, and 42 days after the bands were applied. A linear regression model was built to assess average daily gain, whereas a repeated measures model was used to evaluate body weight differences at each of the measured timepoints. Furthermore, logistic regression models were used to evaluate associations with casting outcomes. Few differences were noted between treatment groups with respect to casting success for the scrotum and tail and ADG over the entire experimental period. Non-inferiority calculations demonstrated no differences in tail docking and scrotal casting success, with casting occurring for the majority of animals by d 21 and d 42 for castration and tail docking, respectively. However, lambs receiving LLBs gained more weight from d -3 to 7 (+0.03 kg/d; 95% CI: 0 to 0.07), which may be an indication of effective pain control during the first week following band application. Overall, the use of an LLB does not affect the time to successful casting of the tail and could improve short-term growth when compared to a control band. Further studies are needed to compare LLBs to multimodal methods of pain relief.

An Exploration of Analgesia Options for Australian Sheep

During their lifetime, sheep undergo many painful husbandry and disease processes. Procedures undertaken on the farm, such as tail docking, castration, and mulesing, all cause considerable pain. In addition, sheep may experience painful diseases and injuries that require treatment by veterinary practitioners, and in biomedical research, sheep may undergo painful experimental procedures or conditions. It is important due to ethics, animal welfare, social licence, and, at times, legal requirements for farmers, veterinary practitioners, and researchers to provide pain relief for animals in their care. While there is a heightened awareness of and a greater interest in animal welfare, there remain few licensed and known analgesia options for sheep within Australia. A literature review was undertaken to identify currently known and potential future options for analgesic agents in sheep in farm and biomedical settings. Non-steroidal anti-inflammatories, opioids, local anaesthetics, α2 adrenoreceptor agonists, and NMDA receptor antagonists are some of the more common classes of analgesic drugs referred to in the literature, but few drugs are registered for use in sheep, with even fewer proven to be effective. Only six analgesic product formulations, namely, lignocaine (e.g., Numocaine®), Tri-Solfen®, ketamine, xylazine, and meloxicam (oral transmucosal and injectable formulations), are currently registered in Australia and known to be efficacious in some types of painful conditions in sheep. The gap in knowledge and availability of analgesia in sheep can pose risks to animal welfare, social licence, and research outcomes. This article presents a summary of analgesic agents that have been used in sheep on farms and in clinical veterinary and biomedical research settings along with details on whether their efficacy was assessed, doses, routes of administration, indication for use, and pain assessment techniques (if any) used. The outcome of this research highlights the challenges, gaps, and opportunities for better analgesia options in sheep.

Assessment of the Pharmacokinetics and Pharmacodynamics of Injectable Lidocaine and a Lidocaine-Impregnated Latex Band for Castration and Tail Docking in Lambs

The objectives of this study were to assess the pharmacokinetics and pharmacodynamics of the current standard-of-care for pain mitigation in lambs during castration and tail docking (injectable lidocaine) and assess the ability of Lidocaine-Loaded Bands (LLBs) to deliver therapeutic concentrations into the contacted tissues over time. The study was comprised of four different trials: (1) investigation of in vitro release of lidocaine from LLBs; (2) pharmacokinetics and pharmacodynamics of injectable lidocaine in scrotal and tail tissue; (3) pharmacokinetics and pharmacodynamics of in vivo delivery of lidocaine with LLBs placed on the tail and scrotum of lambs; and (4) a "proof-of-concept" study comparing the sensation of control- versus LLB-banded tail tissue over time. The use of injectable lidocaine provides effective short-term anesthesia for 120 to 180 min following the injection; however, additional strategies are needed to manage long-term pain. The use of an LLB could provide an alternative where tissue lidocaine concentrations meet or exceed the EC50 for at least 21-28 days and, based on electrostimulation data, provides local anesthesia for at least 3 days when compared to a control band. Further studies are needed to compare the use of an injectable local anesthetic to the LLBs.

Intrathecal adenosine enhances the antinociception of Xylazine in goats

Background

The role of adenosine (AD) in neuromodulation of nociceptive signaling at the level of the spinal cord has been established in both preclinical and clinical models. Recently, the signaling pathway that involves adenosine 5-monophosphate activated protein kinase has been reported to mediate the antinociceptive effects of xylazine (XYL). The objective of this study was to investigate the antinociceptive, cardiorespiratory and hematological effects of intrathecal administration of combined XYL-AD in goats as compared to XYL alone. Six clinically healthy adult goats weighing 25 ± 2 kg were randomly assigned to one of three groups in a cross-over design. Goats were sedated with XYL (0.05 mg/kg, IM) in all groups. Ten min later, 0.9% saline solution [SAL group], XYL (0.05 mg/kg) [XYL group] or a combination of XYL (0.05 mg/kg) and AD (2000 µg) [XYL-AD group] was injected intrathecally. Antinociception scores and both cardiorespiratory and hematological parameters were measured before XYL sedation and intrathecal injection (baseline), and at 5, 10, 15, 30, 60, 90, 120 and 150 min thereafter.

Results

The XYL-AD group showed significantly earlier onset of antinociception [5 (5–7) min] than XYL [13 (12–14.25] min (P = 0.031). The duration of complete antinociception in goats that received XYL-AD was significantly longer (P = 0.031) than that received XYL alone [65 (58.75–66.25) and 47.5 (43.75–51.25) min, respectively]. In both XYL and XYL-AD groups, heart rate (HR), arterial blood pressure (SAP, MAP and DAP) were significantly decreased (P < 0.05) compared to the baseline. Compared to the SAL group, a statistically significant reduction in HR from 10 to 150 min (P < 0.05) was detected in the XYL group contrary to the XYL-AD group. Differences in the hematological parameters among different groups were insignificant.

Conclusions

AD injected intrathecally interacts synergistically with XYL to promote antinociception in goats. This discovery supports the use of AD in combination with XYL in clinical trials.

Three Studies Evaluating the Potential for Lidocaine, Bupivacaine or Procaine to Reduce Pain-Related Behaviors following Ring Castration and/or Tail Docking in Lambs

Simple Summary

Lambs are routinely castrated and/or tail docked. Local anesthesia could improve lamb welfare, but data on the duration of effect of local anesthetics are not available. This study evaluated the efficacy of lidocaine, procaine, or bupivacaine in terms of the behavioral response to castration and/or tail docking. The benefits of local anesthetics were modest. The effects of procaine appear to last longer than lidocaine, while bupivacaine is slower to take effect but may provide longer-lasting pain relief. The duration of action of local anesthetics is limited in sheep, and detailed behavioral evaluations are required in the first hour post-procedure to observe efficacy.

Abstract

The use of local anesthesia at the time of ring castration and tail docking can improve lamb welfare. However, few local anesthetics are registered for sheep, and data on their duration of effect is limited. Three studies were conducted to evaluate the efficacy of procaine (P), lidocaine (L), and bupivacaine (B) in terms of observed alleviation of behavioral responses to castration and/or tail docking in 10-min blocks in the first 60 min post-treatment. In each study, comparisons were made between two groups of lambs castrated and/or tail docked with rubber rings and either receiving the agent using the NUMNUTS^® instrument (N) or receiving no anesthetic agent (RR). Acute pain behavior was lower in NL (n = 28) than RRL (n = 15) males in the first 10 min post-procedure (p < 0.05); lower in NB (n = 16) than RRB (n = 16) males in periods 10–20 min (0.05 < p < 0.01), 20–30 min (p < 0.05) and 40–50 min (0.05 < p < 0.01); lower in NB (n = 16) than RRB (n = 16) females between 20 and 40 min post-procedure (0.05 < p < 0.01); lower in NP (n = 8) than RRP (n = 7) males in period 10–20 min (0.05 < p < 0.01), and lower in NP (n = 9) than RRP (n = 9) females in periods 0–10 min (0.05 < p < 0.01), and 10–40 min (p < 0.05). Benefits were modest, and the effects of procaine appear to last longer than lidocaine, while bupivacaine is slower to take effect than either procaine or lidocaine but may provide longer-lasting pain relief. The duration of action of local anesthetics is short in sheep, and detailed behavioral evaluations are required in the first hour post-procedure to establish efficacy.

Analgesia for Sheep in Commercial Production: Where to Next?

Simple Summary

Increasing societal and customer pressure to provide animals with ‘a life worth living’ continues to apply pressure on industry to alleviate pain associated with husbandry practices, injury and illness. Although a number of analgesic solutions are now available for sheep, providing some amelioration of the acute pain responses, this review has highlighted a number of potential areas for further research.

Abstract

Increasing societal and customer pressure to provide animals with ‘a life worth living’ continues to apply pressure on livestock production industries to alleviate pain associated with husbandry practices, injury and illness. Over the past 15–20 years, there has been considerable research effort to understand and develop mitigation strategies for painful husbandry procedures in sheep, leading to the successful launch of analgesic approaches specific to sheep in a number of countries. However, even with multi-modal approaches to analgesia, using both local anaesthetic and non-steroidal anti-inflammatory drugs (NSAID), pain is not obliterated, and the challenge of pain mitigation and phasing out of painful husbandry practices remains. It is timely to review and reflect on progress to date in order to strategically focus on the most important challenges, and the avenues which offer the greatest potential to be incorporated into industry practice in a process of continuous improvement. A structured, systematic literature search was carried out, incorporating peer-reviewed scientific literature in the period 2000–2019. An enormous volume of research is underway, testament to the fact that we have not solved the pain and analgesia challenge for any species, including our own. This review has highlighted a number of potential areas for further research.

Use and Efficacy of Analgesic Agents in Sheep (Ovis aries) Used in Biomedical Research

Sheep (Ovis aries) are widely used as large animal models in biomedical research. However, current literature on the use of analgesics in sheep generally focuses on an industry or farm level of use. This structured review evaluates use and efficacy of analgesics administered to sheep in a biomedical research setting. Electronic databases were searched with terms related to analgesia in research sheep. After application of exclusion criteria, 29 peer-reviewed publications were evaluated from 1995 to 2018. Drugs used for analgesia in sheep include opioids, α₂ agonists, NSAID, local anesthetics, NMDA receptor antagonists, and calcium channel blockers. Opioid agonists have previously been considered short acting and of questionable efficacy in sheep, but newer modalities may provide effective analgesia. NSAID may exhibit an analgesic effect only when inflammatory pain is present and may not be beneficial for use in acute pain models. α₂ agonists provide effective yet short-lived analgesia; however, side effects are of concern. Local anesthetics were previously widely used as stand-alone agents, as alternatives to the use of general anesthetics in sheep. These agents have since fallen out of favor as sole agents. Despite this, they provide a valuable analgesic effect when used as adjuncts to general anesthetic regimes. The NMDA antagonist ketamine provided good analgesia and is likely underutilized as an analgesic agent in sheep. Future controlled studies should further evaluate the analgesic properties of ketamine in sheep.

Prospective evaluation of complications of the usage of buffering lidocaine for secondary intention healing

BACKGROUND

Circular excision by secondary-intention healing is useful for small skin defects (diameter <10 mm). But the injection pain as the local anesthesia is administered one of the patients' biggest concerns. Buffered lidocaine can effectively relieve the injection pain, but it might increase the potential complications. This study examined the effect of buffered lidocaine on wound healing.

METHODS

Patients undergoing circular excision by secondary-intention healing were divided into 2 groups and were administered buffered or unbuffered lidocaine as the local anesthesia. Comparative parameters included injection pain, postoperative pain, complication rate, scar width, and scar quality at 6 months. Statistical differences between the 2 agents were assessed.

RESULTS

The patients in the buffered group experienced 0.9 fewer scaled injection pain units than did the patients in the unbuffered group (p = 0.009). Complication rates and scar appearance did not show any statistical difference between the 2 groups.

CONCLUSION

Buffered lidocaine is useful to relieve the injection pain during the secondary-intention healing, and it is safe to use if it is applied properly.

Comparison of Two Doses of Ropivacaine Hydrochloride for Lumbosacral Epidural Anaesthesia in Goats Undergoing Laparoscopy Assisted Embryo Transfer

Goats (n = 12) undergoing laparoscopy assisted embryo transfer were randomly allotted to two groups (I and II) and injected same volume of ropivacaine hydrochloride at 1.0 mg/kg and 0.5 mg/kg body weight, respectively, at the lumbosacral epidural space. The hind quarters of all the animals were lifted up for the first 3.0 minutes following injection. Immediately after induction the animals were restrained in dorsal recumbency in Trendelenburg position in a cradle. Laparoscopy was performed after achieving pneumoperitoneum using filtered room air. Regional analgesia and changes in physiological parameters were recorded. The mean induction time in animals of group I (n = 6) was 12.666 ± 1.994 minutes. In these animals the analgesia extended up to the umbilical region and lasted for 60 minutes. Only two animals in group II were satisfactorily induced in 11.333 ± 2.333 minutes. In animals of group I, the time taken for regaining the full motor power was significantly long (405 ± 46.314 min) when compared to group II goats (95 ± 9.219 min). From this study it was concluded that ropivacaine did not produce adequate analgesia in most of the goats at 0.5 mg/kg. When used at 1.0 mg/kg, it produced satisfactory regional analgesia lasting for one hour but the prolonged motor loss precludes its use. Additional studies using ropivacaine hydrochloride at doses in between the two extremes used here may be undertaken before recommending it for lumbosacral anaesthesia in goats undergoing laparoscopy.