Effects of administration of a local anaesthetic and/or an NSAID and of docking length on the behaviour of piglets during 5 h after tail docking

Public and industry knowledge and perceptions of US swine industry castration practices

In the United States (US), surgical castration of male piglets is typically performed without any form of analgesia. This may raise concerns with the public; however, there is no information regarding current public knowledge on swine industry practices in the US. In this study we gained insight into public knowledge and perception on castration with and without analgesia in comparison to knowledge of industry stakeholders on these same topics. Through an online survey, 119 respondents were asked four questions about castration in the US swine industry. Industry respondents were contacted via social media and networking. The general public sample was accessed through Mechanical Turk. Survey responses were categorised by experience (industry vs public). Industry respondents were more aware of practices compared to the general public. Most public respondents were unaware of castration practices and the lack of analgesia use. Respondents from rural communities were more aware of castration practices than (sub)urban communities and more aware of analgesia use than those from urban communities. Those with more education had greater awareness of castration practices (occurrence not frequency). Based on the results from this first US sample, knowledge on industry practices was especially lacking for public respondents, but also for a minority of industry respondents, indicating opportunities for education and further research on the topic.

Scientific and technical assistance on welfare aspects related to housing and health of cats and dogs in commercial breeding establishments

This Scientific Report addresses a mandate from the European Commission according to Article 31 of Regulation (EC) No 178/2002 on the welfare of cats and dogs in commercial breeding establishments kept for sport, hunting and companion purposes. The aim was to scrutinise recent recommendations made by the EU Platform on Animal Welfare Voluntary Initiative on measures to assist the preparation of policy options for the legal framework of commercial breeding of cats and dogs. Specifically, the main question addressed was if there is scientific evidence to support the measures for protection of cats and dogs in commercial breeding related to housing, health considerations and painful procedures. Three judgements were carried out based on scientific literature reviews and, where possible a review of national regulations. The first judgement addressed housing and included: type of accommodation, outdoor access, exercise, social behaviour, housing temperature and light requirements. The second judgement addressed health and included: age at first and last breeding, and breeding frequency. Judgement 3 addressed painful procedures (mutilations or convenience surgeries) and included: ear cropping, tail docking and vocal cord resections in dogs and declawing in cats. For each of these judgements, considerations were provided indicating where scientific literature is available to support recommendations on providing or avoiding specific housing, health or painful surgical interventions. Areas where evidence is lacking are indicated.

Welfare of pigs on farm

This scientific opinion focuses on the welfare of pigs on farm, and is based on literature and expert opinion. All pig categories were assessed: gilts and dry sows, farrowing and lactating sows, suckling piglets, weaners, rearing pigs and boars. The most relevant husbandry systems used in Europe are described. For each system, highly relevant welfare consequences were identified, as well as related animal-based measures (ABMs), and hazards leading to the welfare consequences. Moreover, measures to prevent or correct the hazards and/or mitigate the welfare consequences are recommended. Recommendations are also provided on quantitative or qualitative criteria to answer specific questions on the welfare of pigs related to tail biting and related to the European Citizen's Initiative 'End the Cage Age'. For example, the AHAW Panel recommends how to mitigate group stress when dry sows and gilts are grouped immediately after weaning or in early pregnancy. Results of a comparative qualitative assessment suggested that long-stemmed or long-cut straw, hay or haylage is the most suitable material for nest-building. A period of time will be needed for staff and animals to adapt to housing lactating sows and their piglets in farrowing pens (as opposed to crates) before achieving stable welfare outcomes. The panel recommends a minimum available space to the lactating sow to ensure piglet welfare (measured by live-born piglet mortality). Among the main risk factors for tail biting are space allowance, types of flooring, air quality, health status and diet composition, while weaning age was not associated directly with tail biting in later life. The relationship between the availability of space and growth rate, lying behaviour and tail biting in rearing pigs is quantified and presented. Finally, the panel suggests a set of ABMs to use at slaughter for monitoring on-farm welfare of cull sows and rearing pigs.

Impact of Routine Management Procedures on the Welfare of Suckling Piglets

Piglets often undergo several painful treatments during the initial days of their lives. In this review, we investigate the acute (i.e., immediate), short-, and long-term implications of piglet processing on behavioral, physiological, clinical, and performance parameters, and how welfare impairments depend on performance instead of sham procedure, alternative techniques, or the age of the piglets. Welfare indicators that have been used to determine the least distressing procedures and knowledge gaps with regard to the procedures are identified and discussed. Tail docking and especially piglet castration have been the most researched topics, whereas marking for identification has been rarely addressed. Few or no studies have investigated the effects of teeth resection and tail docking on piglets of different age groups. Additionally, results are often found to be inconsistent, highlighting the need for additional research to determine the optimal age for processing. Studies comparing different processing techniques have produced contradictory results, but ear notching, teeth clipping, hot cautery tail docking, and tearing during castration have been determined to result in increased pain. Generally, a shorter procedure duration can reduce stress, with operator training having a distinct impact on piglet welfare during processing. As such, these topics should be further investigated.

Tranquillizing Effect of Passiflora incarnata Extract: Outcome on Behavioral and Physiological Indicators in Weaning Pigs with Intact Tails

Simple Summary

Post-weaning is the most critical phase in pig farming, characterized by efforts to ensure health, performance and welfare of animals. Despite that EU Directive 2008/120/EC prohibits the practice of tail docking, it is still commonly applied in intensive farming to avoid tail biting. From a nutritional perspective, the dietary supplementation with natural extracts with calming properties could represent a promising approach to overcome common production stressors, reducing abnormal behaviors such as tail biting. This study intended to determine the effects of the dietary inclusion of Passiflora incarnata, known for its tranquillizing activity, on skin lesions, thermal imaging, behavior, salivary cortisol and IgA levels on post-weaning piglets reared with intact tails. Growth performances were also monitored. No differences were recorded between diets regarding growth performance, whereas findings concerning aggressive and abnormal behaviors, such as tail and ear biting, and lower levels of cortisol confirmed the hypothesis of the calming effect of P. incarnata on post-weaning piglets.

Abstract

Tail docking has been used in the pig industry to decrease the occurrence of tail biting behavior. This abnormal behavior has a multifactorial origin since it is a response to simultaneous environmental, nutritional and management changes. Given the calming properties of Passiflora incarnata, we hypothesized that dietary supplementation with the extract in weaned pigs could result in a modification of behavior and physiologic indicators linked to stress. Weaned piglets (n = 120, mean body weight 9.07 ± 2.30 kg) were randomly allocated to one of two dietary treatments: control diet (CON) and CON supplemented with 1 kg/t of P. incarnata (PAS). The trial was 28 days long. The presence of skin lesions was assessed at d-1, d-10, d-19, and d-28, and saliva samples were collected for IgA and cortisol determinations at the same sampling times. Results showed the PAS group was characterized by equal growth performance as the CON group, fewer ear lesions (p < 0.05), less aggressive behavior (p < 0.001), higher enrichment exploration (p < 0.001) and lower cortisol levels (p < 0.01). Time effect was observed for tail lesions (p < 0.001) and behavioral observations (p < 0.001). Additional research is required to determine the effect of P. incarnata extract using a larger number of animals and longer period of supplementation when risks associated with tail biting are uncontrolled.

Comparative effects of nonsteroidal anti-inflammatory drugs at castration and tail-docking in neonatal piglets

This study assessed the efficacy of meloxicam, flunixin, and ketoprofen in piglets undergoing routine castration and tail-docking. Six-day-old male piglets (8/group) received one of five randomized treatments: intramuscular saline (SAL PROC), meloxicam (MEL; 0.4 mg/kg), flunixin (FLU; 2.2 mg/kg), ketoprofen (KETO; 3.0 mg/kg) or sham (SAL SHAM; saline injection, no processing). Two hours post-dose, piglets were castrated and tail-docked. Plasma cortisol, interstitial fluid (ISF) prostaglandin E2 (PGE2) and activity levels via Actical® monitoring were used to estimate pain. SAL SHAM and FLU exhibited lower cortisol concentrations than SAL PROC at the time of processing (p = 0.003 and p = 0.049, respectively), and all NSAIDs exhibited lower PGE2 than SAL PROC at 3.69 hours (MEL p = 0.050; FLU p = 0.043 and KETO p = 0.031). While not statistically significant, PGE2 was higher in SAL PROC piglets vs. other treatment groups at most time points. There was also a high degree of variability between piglets, especially for SAL PROC. Activity levels were significantly decreased at multiple time points in SAL PROC and MEL piglets following processing. However, FLU and KETO piglets had increased activity levels closer to that of the SAL SHAM group, suggesting that these NSAIDs are more effective than MEL in providing analgesia. These results demonstrate that management strategies including administration of intramuscular flunixin or ketoprofen to reduce pain associated with processing will likely improve piglet health and welfare in the United States.

A systematic review of porcine models in translational pain research

Translating basic pain research from rodents to humans has proven to be a challenging task. Efforts have been made to develop preclinical large animal models of pain, such as the pig. However, no consistent overview and comparison of pig models of pain are currently available. Therefore, in this review, our primary aim was to identify the available pig models in pain research and compare these models in terms of intensity and duration. First, we systematically searched Proquest, Scopus and Web of Science and compared the duration for which the pigs were significantly sensitized as well as the intensity of mechanical sensitization. We searched models within the specific field of pain and adjacent fields in which pain induction or assessment is relevant, such as pig production. Second, we compared assessment methodologies in surrogate pain models in humans and pigs to identify areas of overlap and possible improvement. Based on the literature search, 23 types of porcine pain models were identified; 13 of which could be compared quantitatively. The induced sensitization lasted from hours to months and intensities ranged from insignificant to the maximum attainable. We also found a near to complete overlap of assessment methodologies between human and pig models within the area of peripheral neurophysiology, which allows for direct comparison of results obtained in the two species. In spite of this overlap, further development of pain assessment methodologies is still needed. We suggest that central nervous system electrophysiology, such as electroencephalography, electrocorticography or intracortical recordings, may pave the way for future objective pain assessment.

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.

Risk factors associated with tail damage in conventional non-docked pigs throughout the lactation and rearing period

Tail biting is an abnormal behaviour in pigs, and remains an economic and welfare problem in modern pig production. Reasons for performing tail-biting behaviour are of multifactorial origin, and are often related to the current environment or internal characteristics of pigs. The objective of the present study was to identify early life risk factors connected to tail damage in non-docked pigs in a commercial Danish piggery, and to further compare the effects of cumulative cross-life experience throughout the early rearing. In an observational study, 741 piglets from 51 sows born in six batches were individually marked at birth and followed until nine weeks of age. Litter related variables and individual piglet characteristics were collected during lactation. The pigs' performance parameters were recorded from birth to nine weeks of age. The association between putative risk factors and tail damage assessed at different stages during lactation and rearing was analysed using multinomial mixed regression models. Prior to weaning, the odds of having tail damage were higher for piglets originating from litters with a high birth weight variation (P = 0.012) and for piglets that were heavier at weaning (P < 0.001). Piglets born to an aggressive sow had 2.7-fold increased odds of having tail damage (P = 0.003), while piglets of sows treated after farrowing had a lower odds (P = 0.015). Post-weaning, the most significant risk factor(s) associated with tail damage was the previous tail status of the pigs. Pigs with bite marks/ scratches in previous assessments had an on average 4-fold and pigs with a tail wound 11-fold increased odds of having tail damage during subsequent assessments. Similarly, pigs with a tail wound pre-weaning had 7-times higher odds of having tail damage at the end of rearing (P = 0.033). Pigs in groups with a higher weight variation (P = 0.030) and pigs with a greater weight gain (P < 0.001) had higher odds of having tail damage at the end of rearing. There was an increased chance of having tail damage post-weaning for piglets that were cross-fostered (P = 0.032) or that had a clinical impairment (P = 0.047) during lactation. Females generally had a lower chance of having tail damage compared to castrated males. Early life risk factors were especially associated with tail damage in pigs pre-weaning. However, the results of this study suggest that early life risk factors are secondary to the previous tail status of pigs as risk factors for later tail damage.

Tail Docking of Piglets 2: Effects of Meloxicam on the Stress Response to Tail Docking

This experiment assessed the efficacy of the cauterisation procedure with or without pain relief (injectable meloxicam) in mitigating the acute stress response to tail docking. Male piglets (n = 432) were allocated to the following treatments at 2-d post-farrowing: (1) no handling, (2) sham handling, (3) tail docked using clippers, (4) tail docked using a cauteriser, (5) meloxicam + clipper, and (6) meloxicam + cauteriser. Meloxicam treatments used Metacam® at 5 mg/mL injected i.m. 1 h prior to tail docking. Blood samples were collected at 15 and 30 min post-treatment and analysed for total plasma cortisol. Behaviours indicative of pain such as escape attempts, vocalisations and standing with head lowered were measured. The duration of vocalisations and frequency of escape attempts during treatment were greater in all tail docking treatments compared to the sham treatment. Piglets in the clipper treatment had higher (p < 0.05) cortisol concentrations at 30 min but not 15 min after treatment and stood for longer (p < 0.001) with head lowered in the first 60 min after treatment than those in the cauterisation treatment. Meloxicam reduced (p < 0.05) both the cortisol response at 30 min after tail docking with the clipper as well as the behavioural response in the first 60 min after tail docking with the clipper. In comparison to the sham treatment, cortisol concentrations at 15 min were higher in the two tail docking treatments whereas the tail docking treatments with meloxicam were similar to the sham handling treatment. In comparison to the sham handling treatment, cortisol concentrations at 30 min post-docking were higher (p < 0.05) only in the clipper treatment. While cauterisation appears to be less aversive than the clipper procedure, the administration of meloxicam did not mitigate the behavioural response during tail docking using either procedure, but reduced standing with head lowered in the first hour after docking for both methods. The commercial viability of administration of meloxicam requires consideration before it is recommended for use compared to cauterisation alone, as it requires additional handling of piglets and costs.

Intact Tails as a Welfare Indicator in Finishing Pigs? Scoring of Tail Lesions and Defining Intact Tails in Undocked Pigs at the Abattoir

Tail biting lesions are a potential measure of on-farm animal welfare, as a large range of stressors increase the risk for tail biting outbreaks. Further, tail biting is a major challenge, as lesions due to tail biting decrease animal welfare and health, as well as production efficiency and carcass quality. The aim of this study was to suggest a tail scoring system for use at slaughterhouses processing undocked pigs, and to link tail lesion scores to meat inspection data. A further aim was to suggest a definition for an intact enough tail. To validate the suggested scoring system we assessed tails before and after scalding and compared results to pathological examinations. In total, 14,433 tails were scored, and 117 tails were collected for pathological examination. After scalding, 49.2% of all tails were scored as fully intact. Of tails with lesions 2.5% were scored as having major acute wounds (>2 cm), while 11.6% had minor acute wounds (<2 cm), and 36.7% healed lesions. Intact tails were on average 31.5 cm (SD 2.5 cm) long. Lesion scored at the slaughter-line agreed well with the pathological assessment. Tail lesions were associated with several meat inspection findings: tails with more severe lesions and of shorter length increased the risk for meat inspection findings to a higher degree. A detailed lesion scoring method helps to identify carcasses at risk for condemnations, as well as being a potential method for on-farm welfare estimation. We suggest that a system for scoring tail lesions in undocked pigs should utilize a combination of scoring of the lesion and measuring the tail length. As bite marks or bruises on an otherwise intact tail were not a concern for meat hygiene, we suggest the definition of an intact enough tail could allow the inclusion of tails with these mild changes. Meat inspection findings in carcasses with tails scored as healed, but with no fresh lesions, and with more than 75% of the average intact length remaining were rather similar to those of fully intact tails. Based on these findings we suggest that a tail of this length, and with no visible fresh lesions could also be considered intact enough.

Transcriptomics Analysis of Porcine Caudal Dorsal Root Ganglia in Tail Amputated Pigs Shows Long-Term Effects on Many Pain-Associated Genes

Tail amputation by tail docking or as an extreme consequence of tail biting in commercial pig production potentially has serious implications for animal welfare. Tail amputation causes peripheral nerve injury that might be associated with lasting chronic pain. The aim of this study was to investigate the short- and long-term effects of tail amputation in pigs on caudal DRG gene expression at different stages of development, particularly in relation to genes associated with nociception and pain. Microarrays were used to analyse whole DRG transcriptomes from tail amputated and sham-treated pigs 1, 8, and 16 weeks following tail treatment at either 3 or 63 days of age (8 pigs/treatment/age/time after treatment; n = 96). Tail amputation induced marked changes in gene expression (up and down) compared to sham-treated intact controls for all treatment ages and time points after tail treatment. Sustained changes in gene expression in tail amputated pigs were still evident 4 months after tail injury. Gene correlation network analysis revealed two co-expression clusters associated with amputation: Cluster A (759 down-regulated) and Cluster B (273 up-regulated) genes. Gene ontology (GO) enrichment analysis identified 124 genes in Cluster A and 61 genes in Cluster B associated with both “inflammatory pain” and “neuropathic pain.” In Cluster A, gene family members of ion channels e.g., voltage-gated potassium channels (VGPC) and receptors e.g., GABA receptors, were significantly down-regulated compared to shams, both of which are linked to increased peripheral nerve excitability after axotomy. Up-regulated gene families in Cluster B were linked to transcriptional regulation, inflammation, tissue remodeling, and regulatory neuropeptide activity. These findings, demonstrate that tail amputation causes sustained transcriptomic expression changes in caudal DRG cells involved in inflammatory and neuropathic pain pathways.

Welfare Effects of the Use of a Combination of Local Anesthesia and NSAID for Disbudding Analgesia in Dairy Calves-Reviewed Across Different Welfare Concerns

Across the international dairy industry, the vast majority of dairy herds have dehorned cows. Farmers choose to dehorn calves for different reasons such as easier handling of non-horned cattle and reduced risk of injuries in animals and staff. This review focuses on disbudding by use of hot-iron cautery as is practiced by dairy farmers in calves <3 months of age. We examine welfare effects of the use of NSAIDs in combination with a local anesthetic including indicators relevant for the three major welfare concerns-affective states, basic health, and functioning as well as the possibility to behave naturally. Across indicators of animal welfare, the majority of available evidence suggest that the use of NSAIDs in combination with a local anesthetic is advantageous in terms of animal welfare, and no studies suggest that NSAIDs are a disadvantage to animal welfare. However, irrespective of the welfare concern, use of NSAIDs combined with a local anesthetic does not fully eliminate the welfare challenges from disbudding. Further research is needed in order to fully understand the effects of this medication protocol on calf welfare, including knowledge about the duration of healing and the presence of long-term pain. At present, this lack of knowledge challenges the precise formulation of adequate pain management-in terms of medication protocol, duration, dosage, and type of administration.

Effects of tail docking and tail biting on performance and welfare of growing-finishing pigs in a confinement housing system

A study was conducted to evaluate the effect of tail docking on the welfare and performance of victimized pigs by tail biting and tail biters. Pigs ( = 240; 25.7 ± 2.9 kg average weight), including 120 pigs that were tail docked at birth and 120 pigs that remained with intact tails, were used. Pigs were housed in 8 pens of 30 pigs in a confinement barn for 16 wk, with 4 pens each housing pigs of both sexes with docked or intact tails. Tail biters and victimized pigs with damaged tails were identified during outbreaks of tail biting. Growth performance was monitored, and skin lesions on the tail, ears, and body were assessed. Blood samples were collected from focal tail biters, victimized pigs, and nonvictimized pigs for analysis of total serum protein, IgG, and substance P concentrations. When pigs were marketed, carcass weights and the number of pigs with carcass trim loss were recorded. During the growing-finishing period, 48% of pigs with docked tails and 89% of pigs with intact tails experienced lesions on their tails, including 5% of docked pigs and 30% of intact pigs identified as victimized pigs that experienced puncture wounds with signs of infection on their tails or loss of tails ( < 0.001). Victimized pigs tended to gain less weight ( = 0.07) between 17 and 21 wk of age than other pigs when tail biting prevailed in this study. Victimized pigs were more frequently ( = 0.04) sold for less than full value and had a lower dressing percentage ( < 0.001) compared with nonvictimized pigs. For victimized pigs, total serum protein and IgG concentrations were elevated 5 d after tails were injured, suggesting that tail damage can cause inflammation, which may lead to carcass abscesses and trim loss. Compared with victimized pigs and nonvictimized pigs, tail biters had lower total serum protein ( = 0.01) and IgG ( = 0.01) concentrations, indicating that tail biters may experience poor immune functions. Results of this study demonstrated that tail docking reduced tail damage in pigs kept in a confinement system. Tail damage can cause inflammation and reduce the value of market pigs. More research is needed to test whether compromised immune functions predispose pigs to tail biting.

The effect of docking length on the risk of tail biting, tail-directed behaviour, aggression and activity level of growing pigs kept under commercial conditions

Tail biting in domestic pigs relates to a range of risk factors, primarily in the pigs' environment. Preventive tail docking is widely used, and various experimental approaches suggest that docking reduces the risk of tail biting. However, whether the docking length affects the prevalence of tail biting outbreaks is less studied, as is how a shortened tail will affect pigs' social behaviour. The aim of this study was to investigate how three different tail docking lengths, measured at docking, as well as retained intact tails (Short: 2.9 cm; Medium: 5.7 cm; Long: 7.5 cm; and Undocked) affected tail biting risk and behaviour directed at other finisher pigs with the same docking length treatment. Tail lesions were scored weekly, as was behaviour at pen level after introduction to finisher pens and until a potential outbreak of tail biting or slaughter. Pigs from four commercial herds (258 litters) entered the study. Before the pigs entered the finisher section and data collection started, some pigs were excluded, mainly due to tail biting outbreaks in the weaner section. The risk of a tail biting outbreak differed significantly between treatments (P=0.001), with a lowered risk of a tail biting outbreak in Short pens compared with Undocked (P<0.001) and Medium (P<0.05), and was affected by herd as well (P<0.001). Pens in the Long and Undocked treatments were pooled for the behavioural analysis due to low representation, especially in the Undocked treatment. The probability of tail contacts, where a pig interacted with a pen mate's tail, differed between docking length treatments and was highest in the Long/Undocked compared with the Short treatment (P<0.01), but docking length did not affect aggressive behaviour. Docking length affected the risk of a tail biting outbreak and the frequency of tail-directed behaviour in our participating herds, of which three reported a high prevalence of tail biting problems. Only the shortest docking length treatment (Short) reduced the tail biting risk, but did not completely prevent tail biting outbreaks.

Docking piglet tails: How much does it hurt and for how long?

Tail docking in pigs has the potential for evoking short- as well as long-term physiological and behavioural changes indicative of pain. Nonetheless, the existing scientific literature has thus far provided somewhat inconsistent data on the intensity and the duration of pain based on varying assessment methodologies and different post-procedural observation times. In this report we describe three response stages (immediate, short- and long-term) through the application of vocalisation, behavioural and nociceptive assessments in order to identify changes indicative of potential pain experienced by the piglets. Furthermore, we evaluated the following procedural differences: (1) cautery vs. non-cautery docking; (2) length of tail removal. Sound parameters showed a significantly greater call energy and intensity exhibited by docked vs. sham-docked piglets (P<0.05). Observations of general activity of the animals in a test situation failed to detect a difference among treatments (P>0.05) up to 48h post-tail docking. Similarly, no difference in mechanical nociceptive thresholds indicative of long term pain was observed at 17weeks following neonatal tail docking (P>0.05). The present results highlight the potential for the use of measures of vocalisation to detect peri-procedural changes possibly associated with evoked pain. Nonetheless, activity and nociceptive measures failed to identify post-docking anomalies, suggesting that alternative methodologies need to be implemented to clarify whether tail docking is associated with short- and long-term changes attributable to pain experienced by the piglets.

Which is the most preventive measure against tail damage in finisher pigs: tail docking, straw provision or lowered stocking density?

One challenge of intensive pig production is tail damage caused by tail biting, and farmers often decrease the prevalence of tail damage through tail docking. However, tail docking is not an optimal preventive measure against tail damage and thus, it would be preferable to replace it. The aim of the current study was to investigate the relative effect of three possible preventive measures against tail damage. The study included 112 pens with 1624 finisher pigs divided between four batches. Pens were randomly assigned to one level of each of three treatments: (1) tail-docked (n=60 pens) v. undocked (n=52 pens), (2) 150 g of straw provided per pig per day on the solid floor (n=56 pens) v. no straw provided (n=56 pens), (3) stocking density of 1.21 m2/pig (11 pig/pen; n=56 pens) v. 0.73 m2/pig (18 pigs/pen; n=56 pens). Tail damage was recorded three times per week throughout the finisher period by scoring the tail of each individual pig. A pen was recorded as a tail damage pen and no longer included in the study if at least one pig in a pen had a bleeding tail wound; thus, only the first incidence of tail damage on pen level was recorded. Data were analysed by a Cox regression for survival analysis assuming proportional hazards. Results are presented as hazards, and a higher hazard means that a pen has a higher risk of tail damage and of it happening earlier in the finisher period. Pens with undocked pigs had a 4.32-fold higher hazard of tail damage compared with pens with docked pigs (P<0.001). Pens with no straw provided had a 2.22-fold higher hazard of tail damage compared with pens with straw provided (P<0.01). No interactions was seen between the treatments, but the effect of tail docking was higher than the effect of straw provision (P<0.001). Stocking density did not have a significant effect on the hazard of tail damage (hazard rate ratios (HRR)=1.67; P=0.064). However, a combination of straw provision and lowered stocking density showed a similar hazard of tail damage as seen with only tail docking (HRR=1.58; P=0.39). In conclusion, tail docking and straw provision were preventive measures against tail damage, and tail docking reduced the risk more than straw provision. A combination of other preventive measures is necessary to reduce the risk of tail damage in undocked pigs to the same level as in docked pigs.

Characterization of short- and long-term mechanical sensitisation following surgical tail amputation in pigs

Commercial pigs are frequently exposed to tail mutilations in the form of preventive husbandry procedures (tail docking) or as a result of abnormal behaviour (tail biting). Although tissue and nerve injuries are well-described causes of pain hypersensitivity in humans and in rodent animal models, there is no information on the changes in local pain sensitivity induced by tail injuries in pigs. To determine the temporal profile of sensitisation, pigs were exposed to surgical tail resections and mechanical nociceptive thresholds (MNT) were measured in the acute (one week post-operatively) and in the long-term (either eight or sixteen weeks post-surgery) phase of recovery. The influence of the degree of amputation on MNTs was also evaluated by comparing three different tail-resection treatments (intact, ‘short tail’, ‘long tail’). A significant reduction in MNTs one week following surgery suggests the occurrence of acute sensitisation. Long-term hypersensitivity was also observed in tail-resected pigs at either two or four months following surgery. Tail amputation in pigs appears to evoke acute and sustained changes in peripheral mechanical sensitivity, which resemble features of neuropathic pain reported in humans and other species and provides new information on implications for the welfare of animals subjected to this type of injury.