Pain alleviation during castration of piglets: a comparative study of different farm options

Uncontrolled pain: a call for better study design

Studies assessing animal pain in veterinary research are often performed primarily for the benefit of animals. Frequently, the goal of these studies is to determine whether the analgesic effect of a novel treatment is clinically meaningful, and therefore has the capacity to improve the welfare of treated animals. To determine the treatment effect of a potential analgesic, control groups are necessary to allow comparison. There are negative control groups (where pain is unattenuated) and positive control groups (where pain is attenuated). Arising out of animal welfare concerns, there is growing reluctance to use negative control groups in pain studies. But for studies where pain is experimentally induced, the absence of a negative control group removes the opportunity to demonstrate that the study methods could differentiate a positive control intervention from doing nothing at all. For studies that are controlled by a single comparison group, the capacity to distinguish treatment effects from experimental noise is more difficult; especially considering that pain studies often involve small sample sizes, small and variable treatment effects, systematic error and use pain assessment measures that are unreliable. Due to these limitations, and with a focus on farm animals, we argue that many pain studies would be enhanced by the simultaneous inclusion of positive and negative control groups. This would help provide study-specific definitions of pain and pain attenuation, thereby permitting more reliable estimates of treatment effects. Adoption of our suggested refinements could improve animal welfare outcomes for millions of animals globally.

Effect of Topical Spray Containing Lidocaine on Piglet Behaviour Post castration

Previous studies examining the impact of topical lidocaine spray on postcastration pain behavior in piglets used scan sampling for the collection of behavior data. This methodology led to inconclusive results on the efficacy of topical lidocaine spray for pain relief. This study uses continuous coding to examine the effect of topical lidocaine on piglet behavior post castration. Castrated piglets received either no pain relief or topical lidocaine spray and are compared to gilts that were handled only. Postcastration piglet behavior was continuously coded for postural behaviors, social isolation, as well as nosing and playing. Behaviors in the castrated piglets differed from those that were handled only, but the piglets that received the spray did not exhibit significantly different behaviors from castrated pigs that received no spray. Play, exploratory behavior, and continuous behavioral observations proved to be sensitive modalities for detecting alterations in behavior postcastration and revealed that topical lidocaine spray does not provide effective pain mitigation for piglets undergoing castration and would thus not be recommended as a method for providing postcastration pain relief in piglets.

A novel transdermal ketoprofen formulation for analgesia in cattle

Ketoprofen is registered in many countries for injectable administration in cattle. Because it is soluble in a wide range of excipients, development of a novel transdermal (TD) ketoprofen formulation was pursued to provide a convenient and pain-free route of administration in cattle. One hundred and six excipient combinations were screened using in vitro techniques (Franz diffusion cells), with a 20%_(w/v) ketoprofen formulation dissolved in a combination of 45%:45%_(v/v) ethanol and isopropyl myristate (IPM) and 10%_(v/v) eucalyptus oil achieving maximal penetration of ketoprofen through bovine skin. A bioavailability study was then conducted using a randomized cross-over design (n = 12), including IV, IM (both 3 mg/kg) and TD (10 mg/kg) ketoprofen formulations administered with a one-week washout period between administrations. The IV and IM formulation pharmacokinetic results were as expected. The C_MAX , T_{max and} AUC_0-Last were significantly higher (arithmetic mean ± SD) after TD administration (20.0 ± 6.5 μg/ml, 115 ± 17 min and 3940 ± 1324 μg*min/ml, respectively), compared to IM (11.0 ± 4.0 μg/ml, 74 ± 43 min and 2376 ± 738 μg*min/ml, respectively), although there were no significant differences for T_½β . However, dose corrected values C_MAX and AUC_inf were significantly higher for IM compared to TD. The arithmetic mean bioavailability (F) of the transdermal formulation was 50%. The plasma concentration of the TD formulation at a dose of 10 mg/kg was similar to the IM formulation at 3 mg/kg by 30 min post-dosing with an arithmetic mean ± SD of 7.97 ± 4.38 vs. 8.02 ± 3.55 μg/ml, respectively. The TD formulation was generally well tolerated by cattle, although some local irritation along the site of application was noted after 12 h of exposure during the bioavailability study. Results indicate that this novel TD formulation provides a substantial improvement in administration convenience, may improve animal welfare and end-user safety through needle-free administration, and achieves similar plasma pharmacokinetics to the IM product when administered at 10 mg/kg.

[Comparison of the efficiency of inhalation and injection anaesthesia for the castration of male suckling piglets in different organic farms]

OBJECTIVE

In Germany, injection and inhalation anesthesia with the addition of an analgesic drug are an interim solution to surgical castration under general anesthesia due to the ban on non-anesthetic castration of male suckling piglets under 8 days of age. However, the efficiency of both anesthetic procedures is submit to controversial discussion. Most of the studies addressing this question only examined one of the procedures in comparison to piglets castrated without anesthesia or uncastrated controls. Comparisons between the anesthesia methods, especially under conditions of organically working farms, are almost completely lacking. The aim of the present study was therefore to compare the efficacy of injection and inhalation anesthesia under practical conditions in 7 organic farms as well as to examine the effect of metamizole administered in addition to meloxicam.

MATERIAL AND METHODS

For this purpose, 514 male suckling piglets were examined with regard to anesthesia efficiency (reflex test, defence behaviour), body temperature, post-operative bleeding and wound healing, post-operative behavior and pain behavior as well as the course of the recovery phase.

RESULTS

The results show a basic superiority of inhalation anesthesia over injection anesthesia, especially in the areas of anesthetic efficacy, thermoregulation and duration of the recovery phase. In 7.7 to 15 % of piglets, the perianal and interclaw reflexes studied were still present at the time of castration. Following injection and inhalation anesthesia, in total 83.6 (25.2 %) of the piglets showed at least one of the following criteria: positive reflex response, clear defensive movements or vocalisations. Body temperature dropped by 0.41 °C under inhalation anesthesia and by 1.82 °C under injection anesthesia. Post-castration bleeding and wound healing were hardly influenced by the type of anesthesia. Almost all piglets showed signs of pain and pain-associated behavior for 5 and 72 hours after castration, regardless of the type of anesthesia. The post-castration recovery phases lasted significantly longer after injection anesthesia (107 minutes) than following inhalation anesthesia (33.3 minutes) until the piglets were returned to the sow.

CONCLUSION

Neither injection nor inhalation anesthesia in spite of additional administration of meloxicam, nor the supplementary use of metamizole, fulfil the EU requirements for painless castration.

CLINICAL RELEVANCE

The necessary analgesia during and after castration of male suckling piglets is not achieved under either isoflurane or ketamine/azaperone anesthesia, despite the use of meloxicam and metamizole.

The Application of 3D Landmark-Based Geometric Morphometrics towards Refinement of the Piglet Grimace Scale

Proper methods of assessment to objectively identify pain are essential for welfare improvements of piglets undergoing surgical castration on commercial farms. The Piglet Grimace Scale (PGS) is used to identify changes in facial expressions caused by acute pain in piglets undergoing tail docking and castration. However, subjective scoring methods are a concern for the validation of the PGS. The objectives of this study were to evaluate and refine the PGS through 3D landmark geometric morphometrics. Male piglets (n = 88) were randomly allocated to one of two treatments: castration and sham-castration. Piglet facial images were taken at four time points (before treatment, immediately post-treatment, 1 h post-treatment, and 4 h post-treatment) using a photogrammetry rig. Images were scored by four raters using five facial action units (FAUs): orbital tightening, ear position, temporal tension, lip contraction, and nose bulge/cheek tension. Three-dimensional facial models were generated and landmarked denoting 3 FAUs (orbital tightening, lip contraction, and nose bulge/cheek tension). Results suggest that orbital tightening and ear position may be reliable FAUs for the PGS. However, neither the PGS nor 3D landmark-based geometric morphometrics were able (both p > 0.10) to reliably identify facial indicators of pain in piglets undergoing castration.

The Neuroimmune Interface and Chronic Pain Through the Lens of Production Animals

Communication between the central nervous system (CNS) and the immune system has gained much attention for its fundamental role in the development of chronic and pathological pain in humans and rodent models. Following peripheral nerve injury, neuroimmune signaling within the CNS plays an important role in the pathophysiological changes in pain sensitivity that lead to chronic pain. In production animals, routine husbandry procedures such as tail docking and castration, often involve some degree of inflammation and peripheral nerve injury and consequently may lead to chronic pain. Our understanding of chronic pain in animals is limited by the difficulty in measuring this pathological pain state. In light of this, we have reviewed the current understanding of chronic pain in production animals. We discuss our ability to measure pain and the implications this has on animal welfare and production outcomes. Further research into the neuroimmune interface in production animals will improve our fundamental understanding of chronic pain and better inform human clinical pain management and animal husbandry practices and interventions.

Efficacy of Intra-Operative Topical Wound Anaesthesia to Mitigate Piglet Castration Pain-A Large, Multi-Centred Field Trial

Simple Summary

Piglet castration causes pain and stress to the animal. Although desperately needed, there are complexities developing safe and effective methods of pain alleviation applicable for on-farm use. Topical anaesthesia, instilled to the wound during surgery, is a newly evolving on-farm method to mitigate castration pain. In the current study, we investigated the use of Tri-Solfen^® (Animal Ethics Pty Ltd, Melbourne, Australia), a topical local anaesthetic and antiseptic formulation, instilled to the wound during the procedure, to alleviate subsequent castration-related pain experienced in piglets. We performed a large, blind, multi-centred trial comparing pain in piglets castrated with or without Tri-Solfen^®. Piglets treated with wound instillation of Tri-Solfen^®, 30 s prior to subsequent castration, showed significantly lower pain-induced motor and vocal responses during the procedure. Acute post-operative pain-related behaviours, evident in piglets in the first 30 min following castration, were also significantly reduced in treated piglets compared with untreated piglets. Using this method, Tri-Solfen^® provides an effective on-farm method to mitigate acute castration-related pain in young piglets.

Abstract

Piglet castration results in acute pain and stress to the animal. There is a critical need for effective on-farm methods of pain mitigation. Local anaesthesia using Tri-Solfen^® (Animal Ethics Pty Ltd., Melbourne, Australia), a topical local anaesthetic and antiseptic formulation instilled to the wound during surgery, is a newly evolving on-farm method to mitigate castration pain. To investigate the efficacy of Tri-Solfen^®, instilled to the wound during the procedure, to alleviate subsequent castration-related pain in neonatal piglets, we performed a large, negatively controlled, randomised field trial in two commercial pig farms in Europe. Piglets (173) were enrolled and randomised to undergo castration with or without Tri-Solfen^®, instilled to the wound immediately following skin incision. A 30 s wait period was then observed prior to completing castration. Efficacy was investigated by measuring pain-induced motor and vocal responses during the subsequent procedure and post-operative pain-related behaviour in treated versus untreated piglets. There was a significant reduction in nociceptive motor and vocal response during castration and in the post-operative pain-related behaviour response in Tri-Solfen^®-treated compared to untreated piglets, in the first 30 min following castration. Although not addressing pain of skin incision, Tri-Solfen^® is effective to mitigate subsequent acute castration-related pain in piglets under commercial production conditions.

Intramuscular vs. Intradermic Needle-Free Vaccination in Piglets: Relevance for Animal Welfare Based on an Aversion Learning Test and Vocalizations

The aim of the present study was to compare intramuscular injection with a needle and intradermic needle-free vaccinations against porcine reproductive and respiratory syndrome (PRRS) in piglets at 28 days old by studying behavioral and physiological reactions. A total of 72 piglets divided into 2 sex-balanced batches were assessed. Within each batch, the piglets were divided into three treatments, which were Hipradermic (0.2 ml of UNISTRAIN® PRRS vaccine administered with an intradermic needle-free device), Intramuscular (IM, 2.0 ml of vaccine), and Control (not vaccinated). Before the vaccination, the piglets were trained to cross a 4-m-long raceway to perform an aversion learning test. The day of vaccination, the time taken to cross the raceway was registered for each piglet at different times: prior to the vaccination and 10 min, 2, 24, 48, and 72 h after the vaccination, to measure variations in these times as signs of aversion to the vaccination process. Vocalizations, as potential signs of pain, were recorded as well at the end of this raceway to analyze their frequency (Hz), duration, and level of pressure (dB) at the moment of vaccination. Salivary cortisol, as a sign of the HPA-axis activity, was assessed 10 min after the vaccination. In addition, activity budgets, local reaction to the vaccine, and serological titer were also considered in the study. Ten minutes after the vaccination, the IM piglets took longer (p < 0.001) to cross the raceway than did the Hipradermic and Control piglets. Vocalizations were significantly different between the three treatments: the Control piglets produced vocalizations with the lowest frequency (p < 0.001) and level of pressure (p < 0.001), and IM with the highest, with Hipradermic in a significant intermediate position (p < 0.001). Accordingly, the day of the vaccination, IM and Hipradermic animals were lying on the side of the vaccine administration a greater proportion of time than were the Control piglets (10, 11, and 6%, respectively; p = 0.027). Salivary cortisol was not significantly different between treatments. The serum titer of antibodies against the PRRS was higher (p < 0.001) in both vaccinated treatments in comparison to the Control piglets. It is concluded that the Hipradermic needle-free vaccination may result in a less aversive experience in piglets than did intramuscular vaccination.

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.

Evaluating the utility of a CO2 surgical laser for piglet castration to reduce pain and improve wound healing: a pilot study

CO₂ surgical lasers are widely used for procedures in veterinary and human medicine. There is evidence to suggest surgery using a CO₂ laser reduces pain and swelling and improves healing time compared with surgery with a scalpel. Millions of piglets in North America are surgically castrated each year using a scalpel. Therefore, piglet welfare may be improved by making refinements to the surgical procedure. The objectives of this preliminary study were to determine the ability of a CO₂ surgical laser to (1) reduce pain and (2) improve wound healing of piglets undergoing surgical castration. Two-day-old male Yorkshire × Landrace piglets were used and randomly assigned to 1 of 3 treatments (n = 10 piglets/treatment group): surgical castration with the CO₂ laser, surgical castration with a scalpel, or sham (uncastrated control). Piglets were video recorded in their pens for 1 hr preprocedure and from 0 to 2, 6 to 8, and at 24 hr postprocedure for behavior scoring. Surgical site images were collected at baseline, 0, 8, 24, 48, 72, 96, 120, 144, and 168 hr postcastration for wound healing assessment. Infrared thermography images of the surgical site were also taken at baseline, 0, 0.5, 8, and 24 hr postprocedure to assess inflammation. Finally, blood was collected from each piglet at baseline and 0.5 hr postcastration to assess cortisol levels, prostaglandin E metabolite and pig-major acute phase protein concentration. Laser-castrated piglets displayed more pain behaviors across the observation period than scalpel-castrated piglets (P = 0.05). Laser-castrated piglets also displayed significantly more agonistic behavior than both scalpel-castrated piglets (P = 0.005) and sham piglets (P = 0.036); yet, laser-castrated piglets had significantly lower temperatures at the site of incision compared with scalpel-castrated piglets (P = 0.0211). There was no significant difference in wound healing or any of the blood parameters assessed between laser-castrated and scalpel-castrated piglets. There was evidence of thermal tissue damage on the scrotum of piglets that were castrated using the CO₂ laser. This may have resulted in the unremarkable healing time and the increased pain behavior observed in this study. The surgical laser technique should be refined before conclusions can be made regarding the utility of a CO₂ laser for piglet castration.

On the Road to End Pig Pain: Knowledge and Attitudes of Brazilian Citizens Regarding Castration

We explored the attitudes of Brazilians towards different methods to deal with boar taint in pork (surgical castration without pain control, SC; surgical castration with pain control, SC+PC; immunocastration, IC; raising entire males, EM). Two surveys (Sv1, n = 441 and Sv2, n = 768) containing closed and open questions were conducted. Nearly 70% of Sv1 and Sv2 participants were unaware that meat of entire males may have boar taint and that SC is widely used in pig production in Brazil. In Sv1, acceptability of SC+PC (63%) and IC (53%) was greater than of SC (15%). In Sv2, acceptability of IC (55%) and EM (52%) was greater than of SC (18%). Open-ended responses indicated that participants objected to inflicting pain to pigs to attain a production goal, and were concerned with organoleptic traits and risks of exogenous residues in pork. Participants' views regarding the potential increases in the cost of meat due to adoption of alternative methods varied; some argued that avoiding pain justifies an increase in the price of pork and others that this would impact especially lower income citizens. Our findings indicate that participants opposed surgical castration without pain control, and supported alternative methods. However, the concern with potential risks of presence of residues in meat, expressed by a few participants, may need to be addressed among consumers.

Local Anesthesia in Piglets Undergoing Castration-A Comparative Study to Investigate the Analgesic Effects of Four Local Anesthetics Based on Defensive Behavior and Side Effects

Simple Summary

More than 80 million male piglets are castrated every year within the first week of life mostly without pain relief in the EU. Castration is performed to prevent boar taint, to minimize aggressive and sexual behavior associated with intact males and to gain a constant quality of meat. It is an important animal welfare issue to eliminate pain caused by castration. Local anesthesia, meaning the sole injection of a local anesthetic into the testicles and in the surrounding tissue of conscious piglets, prior to castration is a currently discussed method in Germany. Thus, it was the aim of the present study to investigate the effect of four local anesthetics (procaine, lidocaine, bupivacaine and mepivacaine) on pain relief during surgical castration in conscious piglets. To assess pain, defensive behavior of piglets undergoing injection and castration was evaluated. In addition, attention was paid to possible side effects. Considering healing, bleeding and weight gain no negative impacts were observed, but impairments of locomotor activity occurred. The results indicate that lidocaine and mepivacaine are able to achieve significant pain relief during the castration procedure, whereas procaine and bupivacaine only during the severing of the spermatic cord.

Abstract

The aim of the present study was to investigate the effect of four local anesthetics on pain relief during surgical castration under standardized conditions in conscious piglets. Therefore, 71 male piglets (three to seven days) were distributed into control groups (handling, castration without anesthesia or analgesia) and local anesthetic trial groups (procaine, lidocaine, bupivacaine, mepivacaine). Then, 20 min prior to castration, animals of the treatment groups, except piglets in the handling group, received an injection of a local anesthetic or sodium chloride of 0.5 mL intratesticularly and 0.5 mL subscrotally. During injection and castration, defensive behavior was evaluated. Locomotor activity, as well as postoperative bleeding, wound healing and average daily weight gain were assessed to detect side effects. The injection caused increased defensive movements, significantly in the bupivacaine group. Lidocaine and mepivacaine significantly reduced defensive movements during castration, and procaine and bupivacaine only during severing of the spermatic cord. Impairments of locomotor activity were found in piglets injected with lidocaine, bupivacaine or sodium chloride. Considering healing, bleeding and weight gain, no negative impacts were observed. In conclusion, lidocaine and mepivacaine were able to achieve significant pain relief during the castration procedure, whereas procaine and bupivacaine only during the severing of the spermatic cord. Moreover, the injection of bupivacaine seemed to be painful itself.

Optimal Methods of Documenting Analgesic Efficacy in Neonatal Piglets Undergoing Castration

Analgesic products for piglet castration are critically needed. This requires extensive animal experimentation such as to meet regulatory-required proof of efficacy. At present, there are no validated methods of assessing pain in neonatal piglets. This poses challenges for investigators to optimize trial design and to meet ethical obligations to minimize the number of animals needed. Pain in neonatal piglets may be subtle, transient, and/or variably expressed and, in the absence of validated methods, investigators must rely on using a range of biochemical, physiological and behavioural variables, many of which appear to have very low (or unknown) sensitivity or specificity for documenting pain, or pain-relieving effects. A previous systematic review of this subject was hampered by the high degree of variability in the literature base both in terms of methods used to assess pain and pain mitigation, as well as in outcomes reported. In this setting we provide a narrative review to assist in determining the optimal methods currently available to detect piglet pain during castration and methods to mitigate castration-induced pain. In overview, the optimal outcome variables identified are nociceptive motor and vocal response scores during castration and quantitative sensory-threshold response testing and pain-associated behaviour scores following castration.

Assessing Pain Control Efficacy of Meloxicam and Ketoprofen When Compounded with Iron Dextran in Nursing Piglets Using A Navigation Chute

The efficacy of analgesics such as meloxicam and ketoprofen to control pain in piglets when mixed with iron dextran (ID) before injection is unknown. The purpose of this study was to compare perceived pain in castrated piglets treated 1 h before castration with either of these drugs alone, or when mixed with ID, by observing the time it takes for piglets to navigate a chute. Piglets were divided into seven treatment groups (n = 25 piglets per treatment group) including castration with analgesia (meloxicam or ketoprofen), castration with analgesic plus ID, castration without analgesic or ID, sham handled and given ID, and sham handled alone. Piglets were placed in a short chute and their time to navigate the chute was recorded at four timepoints following castration. Piglets given meloxicam or ketoprofen, with or without ID did not differ from each other in their chute navigation times. Additionally, these piglets did not differ from treatment groups that were not castrated. Piglets castrated without analgesia had significantly longer navigation times. These results indicate that meloxicam or ketoprofen, whether mixed with ID prior to injection or not, provide similar analgesic efficacy.

Topical wound anaesthesia: efficacy to mitigate piglet castration pain

OBJECTIVE

There is a critical need for safe and effective analgesic treatments to address pain resulting from surgical husbandry procedures in livestock. Piglet castration results in acute pain and stress to the animal; however, it is performed globally on millions of piglets annually, often without any analgesia what-so-ever. Tri-Solfen® (Animal Ethics Pty Ltd, Yarra Glen, Victoria, Australia) is a combination local anaesthetic and antiseptic formulation which, applied topically to wounds, has proven effective, and is registered for use to alleviate pain associated with castration (and other wounds) in lambs and calves in Australia and New Zealand. It is also reported to be effective to reduce pain in piglets following castration.

DESIGN

This randomised, blinded, placebo-controlled study examined the safety and efficacy of the formulation, administered via an adapted wound instillation method, to control pain both during and following piglet castration.

METHOD

Piglets received Tri-Solfen or placebo, instilled to the wound immediately following skin incision. A 30 s wait period was then observed prior to completing castration. Pain mitigation was assessed by grading nociceptive resistance movements and piglet vocal response during castration, as well as by grading response to mechanical sensory stimulation of the wound (von Frey and needlestick) following castration.

RESULTS

There was a significant reduction in nociceptive motor and vocal response during castration and in response to mechanical sensory wound stimulation up to and including 2 h following castration. There were no adverse events.

CONCLUSION

Administered via this method, Tri-Solfen is effective to mitigate acute peri-operative castration pain in piglets.

A novel blood-sampling technique in lactating sows: The mammary vein route

In the pig industry, labour efficiency and animal welfare have become two of the most important factors for achieving technical goals and farming competitiveness. Blood sampling is one of the most common sample-collecting techniques, but routine on-field blood collection can be very demanding for farm operators and the welfare of the animals, in particular for lactating sows. The aim of this study was to describe and investigate the mammary vein as a novel means of blood access in lactating sows that does not require coercive restraint. The study involved a total of 68 sows: 34 animals were sampled from the jugular vein (Group J) and the other 34 sows from the mammary vein (Group M). Labour time and indicators of the sow welfare (vocalizations during collection and serum cortisol concentration in the 30min after the procedure) were collected from the two groups. The total amount of labour required, calculated as the time employed to perform blood collection multiplied by the number of operators involved in performing the technique (one for Group M and two for Group J, one for restraint and one for sampling), was significantly lower in Group M than Group J (Group M, 39.83±29.45s; Group J, 82.73±55.34s; P<0.001). Mean blood volume collected at T₀ was 4.81±2.00mL and 4.84±1.73mL in Group J and Group M, respectively (P>0.05). The percentage of sows that vocalized in Group M was less than in Group J (2.94% vs. 94.12%; P<0.001). Serum cortisol concentrations were not statistically different between the two groups (P>0.05). The present study suggests greater efficiency in terms of saving labour time and reducing sow vocalization during blood collection with the use of mammary vein access compared with jugular vein access.

The Need for a Convergence of Agricultural/Laboratory and Zoo-based Approaches to Animal Welfare

Advances in animal welfare science have led to a high number of studies published for farm, laboratory and zoo animals, with a huge breadth of innovative topic areas and methodologies. This paper investigates the different approaches used to undertake welfare research in farm, laboratory and zoo animals due to the variety of constraints that each group brings. We also set recommendations to how groups can support each other in moving forwards to reduce animal suffering and promote a life worth living, a goal that all parties aim to achieve. We propose that researchers develop more collaborations across species, in particular to focus on the applied component of animal welfare and utilizing positive welfare indicators; facilitate knowledge transfer and share good practice worldwide; and accept small n based studies that can still be scientifically robust and provide individual-based steps into advances in our knowledge. Ultimately, we need to be progressing animal welfare science to a point beyond legislative needs, and ensure that "high animal welfare" becomes an additional mission statement for all animal-based industries.

Behavioural alterations in piglets after surgical castration: Effects of analgesia and anaesthesia

The present study aimed to use behavioural measures to assess pain induced by surgical castration of piglets, and evaluate the efficacy of pain-relief medications. In total, 143 male piglets from 29 sows were used. The treatments included: 1) non-castration (NC; n = 28), 2) castration without medication (SC; n = 29), 3) castration with meloxicam injection 0.4 mg/kg i.m. (ME; n = 28), 4) castration with 0.5 ml of 2% lidocaine in each testicle (LA; n = 29), and 5) castration with general inhalation anaesthesia using isoflurane (1.5%) and meloxicam injection (GA; n = 29). Behaviour was monitored continuously for a ten minute period one hour prior to castration (-1 h), as well as immediately (0 h), one hour (1 h), and two hours (2 h) after castration. Behaviour was also monitored twice (08:00 and 20:00) during the following day. Compared to -1 h, castration induced changes in several behavioural measures in SC piglets at 0 h, suggesting that castration was painful. Furthermore, inactive standing or sitting, tail wagging and aggressive behaviour differed between SC and NC piglets at 0 h. ME and LA piglets spent less time standing or sitting inactively, and LA and GA piglets showed more tail wagging than SC piglets at 0 h (P < 0.05 for all). No other behavioural measures differed among the various groups of castrated piglets. In conclusion, the results indicate that surgical castration is indeed painful. However, the efficacy of various pain-relief protocols in piglets shortly after castration was not verified.

Use of non-steroidal anti-inflammatory drugs in porcine health management

OBJECTIVE

Treatment of inflammation and pain management is an important topic in the welfare of pigs. It is very difficult for veterinary practitioners to choose the most appropriate product for a certain problem. This review aims to summarise and discuss the characteristics of different non-steroidal anti-inflammatory drugs (NSAIDs), as well as paracetamol and metamizole, available for pigs in the European Union.

METHODS

The databases Pubmed, Google Scholar, CliniPharm CliniTox and European Medicines Agency were searched. Relevant terms (eg,'meloxicam', 'fever', 'swine', 'pig', 'inflammation', 'castration', 'pain') were used to search for original articles, reviews and books. Only peer-reviewed articles were used. References from studies were also analysed in order to find additional relevant studies.

CONCLUSION

Studies which have investigated the efficacy of NSAIDs for different conditions, using different treatment regimens, are scarce. Most studies focused on the efficacy of NSAID-related pain alleviation in piglet castration, as well as the anti-inflammatory potential of NSAIDs in experimental inflammation models. Little research has been carried out on the use of metamizole, tolfenamic acid, paracetamol and sodium salicylate and their effect in pigs.

Use of Meloxicam or Ketoprofen for Piglet Pain Control Following Surgical Castration

Surgical castration of piglets is performed routinely on commercial pig farms, to prevent boar taint and minimize aggression. While this procedure is known to be painful, piglets are generally not provided any analgesic for pain relief, leading to welfare concerns. The objectives of this study were to assess the efficacy of two non-steroidal anti-inflammatory drugs (NSAIDs), meloxicam (MEL) (0.4 mg/kg or 1.0 mg/kg) and ketoprofen (KET) (6.0 mg/kg) in reducing behavioral indicators of pain in castrated piglets. This study also examined the utility of the Piglet Grimace Scale (PGS) as a pain assessment tool. Nineteen litters of 5-days-old male piglets (n = 120) were used and piglets within a litter were randomly assigned to one of eight possible treatments: 0.4 mg/kg MEL-castrated or uncastrated, 1.0 mg/kg MEL-castrated or uncastrated, 6.0 mg/kg KET-castrated or uncastrated, saline (castrated control), or sham (uncastrated control). Treatments were administered intramuscularly (IM) 20 min prior to surgical castration. Piglets were video recorded for 1 h pre-procedure, for 8 h immediately post-castration and for another hour, 24 h post-procedure. Twenty-one behaviors and postures were scored continuously for the first 15 min of each hour and 1,156 still images of piglet faces were collected and scored using the PGS. Within each treatment group post-castration, castrated piglets displayed significantly more pain-related behaviors than uncastrated piglets (0.4 mg/kg MEL: p = 0.0339, 1.0 mg/kg MEL: p = 0.0079, 6.0 mg/kg KET: p = 0.0034, Controls: p < 0.0001). Castrated piglets also grimaced significantly more post-procedure than uncastrated piglets (p = 0.0061). Compared to the castrated control, none of the NSAID treatments significantly reduced piglet pain behaviors (0.4 mg/kg MEL: p = 1.0000, 1.0 mg/kg MEL: p = 0.9995, 6.0 mg/kg KET: p = 0.4163) or facial grimacing. Piglets demonstrated significantly more pain behaviors 24 h post-castration than at all other time points (p < 0.0001). The PGS was a less effective measure to detect acute pain; however, our findings suggest it does have utility as a pain assessment tool in neonatal pigs. Our findings also indicate that the use of these NSAIDs were ineffective at alleviating castration-associated pain in piglets.

Pain alleviation in patients undergoing cardiac surgery; presternal local anesthetic and magnesium infiltration versus conventional intravenous analgesia: a randomized double-blind study

Background

Magnesium is one of the effective, safe local anesthetic adjuvants that can exert an analgesic effect in conditions presenting acute and chronic post-sternotomy pain. We studied the efficacy of continuous infusion of presternal magnesium sulfate with bupivacaine for pain relief following cardiac surgery.

Methods

Ninety adult patients undergoing valve replacement cardiac surgery randomly allocated into three groups. In all patients; a presternal catheter was placed for continuous infusion of either 0.125% bupivacaine and 5% magnesium sulfate (3 ml/h for 48 hours) in group 1, or 0.125% bupivacaine only in the same rate in group 2, versus conventional intravenous paracetamol and ketorolac in group 3. Rescue analgesia was iv 25 µg fentanyl. Postoperative Visual Analog Scale (VAS) and fentanyl consumption during the early two postoperative days were assessed. All patients were followed up over two months for occurrence of chronic post-sternotomy pain.

Results

VAS values showed high significant differences during the first 48 hours with the least pain scale in group 1 and significantly least fentanyl consumption (30.8 ± 7 µg in group 1 vs. 69 ± 18 µg in group 2, and 162 ± 3 in group 3 respectively). The incidence of chronic pain has not differed between the three groups although it was more pronounced in group 3.

Conclusions

Continuous presternal bupivacaine and magnesium infusion resulted in better postoperative analgesia than both presternal bupivacaine alone or conventional analgesic groups.

Development of a Piglet Grimace Scale to Evaluate Piglet Pain Using Facial Expressions Following Castration and Tail Docking: A Pilot Study

Facial expressions are increasingly being used to assess pain in non-human species, including rodents, horses, and lambs. The development of these species-specific grimace scales has allowed for more rapid pain detection, which can lead to better animal welfare if intervention promptly occurs. For grimace scales to ever be used as a stand-alone measure of pain, it is important they correlate with established pain assessment tools, such as behavioral analysis. This preliminary study aimed to determine whether piglets exhibit pain grimacing and if these facial expressions correlate with their behavior. It also assessed and compared the behavior of boar piglets given an analgesic and topical anesthetic prior to surgical castration and tail docking to piglets that did not receive anything for pain relief. Five-day-old male Yorkshire piglets (n = 19) from four pens were randomly assigned, within their pen, to one of five possible treatments: meloxicam (0.4 mg/kg, intramuscularly) + EMLA^® cream, meloxicam (0.4 mg/kg, intramuscularly) + non-medicated cream, saline (intramuscularly) + EMLA^® cream, saline (intramuscularly) + non-medicated cream, or no treatment prior to surgical castration and tail docking. Piglet behaviors were video recorded for 8 h immediately after castration, as well as for 1 h at 24 h pre- and post-castration. Their individual behaviors were scored continuously for the first 15 min of every hour of video collected. Facial images were also captured across all time points. A Piglet Grimace Scale (PGS) was developed and used by two observers blinded to treatment, time, and procedure to score over 600 piglet faces. All piglets displayed significant behavioral changes up to 7 h post-castration when compared to baseline, and the use of meloxicam and EMLA^® cream was not associated with a reduction in painful behaviors. Significantly higher PGS scores were noted at 0, 3, 4, and 5 h post-castration when compared to PGS scores at 7 h and there was no effect of treatment. PGS scores significantly correlated with piglet behavioral activity. The results suggest that the PGS may have utility for pain evaluation in neonatal pigs.