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The perception of pain by pigs and implications for farm and veterinary practice

Pigs, Tail biting, Tail docking, , , , ,

The perception of pain by pigs and implications for farm and veterinary practice. Edwards, S., 2016. Royal Dublin Society: Abstracts book of the 24th International Pig Veterinary Society (IPVS) Congress, Dublin, Republic of Ireland 7-10th June 2016. p. 13-17.

Abstract

“Freedom from pain, injury and disease” is one of the fundamental aspects of good animal welfare. However, in commercial pig production there are a number of situations where animals may experience pain. This may result from procedures carried out deliberately for management purposes, or from spontaneous health disorders. In order to make decisions on the ethical justification of procedures and the provision of pain alleviation by appropriate anaesthesia and analgesia, it is necessary to assess the intensity and duration of pain experienced by the animals. A number of behavioural, physiological and molecular methods now exist for such assessment but, since pain is a subjective experience which the individual may express in different ways, interpreting these measures can be a challenge. Better methods are required for the practical on-farm assessment of pain and the provision of analgesia when this occurs.

Paper available in the proceedings.

Traumatic neuroma development in tail docked piglets is not associated with long-term changes in spinal nociceptive processing

Pigs, Tail docking, , , , ,

Traumatic neuroma development in tail docked piglets is not associated with long-term changes in spinal nociceptive processing. By Sandercock, D., S. Smith, J. Coe, P. Di Giminiani, S. Edwards, 2016. Royal Dublin Society: Abstracts book of the 24th International Pig Veterinary Society (IPVS) Congress, Dublin, Republic of Ireland 7-10th June 2016. p. 611.

Abstract

Introduction: Concerns exist over the long term consequences for tail stump pain experienced by piglets after docking, especially in relation to traumatic neuroma development in caudal nerves after docking injury. Neuroma formation may cause detrimental sensory changes in the tail due to altered axonal excitability leading to abnormal sensation or pain.

Aims: To characterize pig tail histopathology at time intervals up to 16 weeks after tail docking and to measure expression of key neuropeptides in caudal dorsal root ganglia and spinal cord neurons associated with (i) peripheral nerve regeneration; activating transcription factor-3 (ATF3), (ii) inflammatory pain; Calcitonin gene-related peptide (CGRP) and (iii) the maintenance of chronic pain; N-methyl D-aspartate (NMDA) ionotropic glutamate receptor subtype 2B (GRIN2B) at the same time points after tail docking injury.

Materials and Methods: Thirty-two female piglets (Landrace/Large White x synthetic sireline) were used (16 docked/16 sham-docked). Piglets were tail docked (amputation of approx. 2/3 of the tail) on post-natal day 3 using a gas hot docking iron. Equivalent sham-docked piglets served as intact controls. Pigs were euthanized by barbiturate overdose 1, 4, 8 and 16 weeks after sham/tail docking. Tail stumps (2 cm) were collected post-mortem for histopathological assessment. Caudal dorsal root ganglia (Ca1-Ca4+) and associated spinal cord were collected for gene expression analysis by real-time quantitative PCR of mRNA.

Results: Non-specific epidermal and dermal changes associated with healing were observed after tail docking. Mild inflammation, ulceration and oedema were present at 1 week. Traumatic neuroma development was a consistent feature from 4 weeks after tail docking. Neuroma axonal dispersion in the tail stump was on-going 16 weeks after tail docking. ATF-3 mRNA was significantly upregulated in caudal DRGs up to 8 weeks after tail docking, but did not differ at 16 weeks compared with sham controls. Both CGRP and GRIN2B mRNA expression was significantly upregulated 1 week after tail docking in caudal spinal cord neurons but were not significantly different from sham-docked pigs thereafter.

Conclusion: Histopathological lesions that occur shortly after tail docking (beyond 1 week) are not likely to induce or maintain pain. The effects of tail docking on peripheral nerve axonal proliferation and dispersion are relatively short-lived and, although still present, are attenuated by 16 weeks after tail docking injury. Changes in peripheral and spinal nociceptive processing associated with possible inflammatory and chronic pain appear to resolve by 4 weeks after tail docking injury.

Poster Sandercock IPVS

Temporal changes in mechanical nociceptive thresholds in juvenile pigs subjected to surgical tail amputation: a model of injury induced by tail biting

Pigs, Tail docking, , , , , ,

Temporal changes in mechanical nociceptive thresholds in juvenile pigs subjected to surgical tail amputation: a model of injury induced by tail biting. By Di Giminiani, P., E. Malcolm, M. Leach, M. Herskin, D. Sandercock, S. Edwards, 2016. Royal Dublin Society: Abstracts book of the 24th International Pig Veterinary Society (IPVS) Congress, Dublin, Republic of Ireland 7-10th June 2016. p. 649.

Abstract

Introduction: Tail biting is a global welfare problem in the pig industry leading to significant tail injury and potential carcass rejection. The temporal effects of such injuries and subsequent healing are presently unknown, although limb amputation in humans can lead to abnormal neural activity and decreased nociceptive thresholds. In order to evaluate potential sensitisation following tail damage, we created a model by surgical amputation of tails, and assessed mechanical nociceptive thresholds.

Materials and Methods: Surgical tail resection was performed to assess the influence of age, extent of tail amputated and time since amputation on thresholds of mechanical nociception. To evaluate the effect of age at the time of injury, female pigs underwent surgery at 9 weeks (±3 days ‘weaner’) (n=19) or 17 weeks (±3 days ‘finisher’) (n=43). The effect of time after amputation was evaluated on 24 pigs at 8 weeks, and 38 pigs at 16 weeks after surgery. The effect of the extent of tail amputated was assessed by assigning the pigs to 3 treatments (‘Intact’: sham-amputation; ‘short tail’: 2/3 of tail removed; ‘long tail’: 1/3 of tail removed). A Pressure Application Measurement device was used to record mechanical nociceptive thresholds (tail flick or tail clamp withdrawal responses). Within a single session, three stimuli were applied to a skin area proximal to the site of amputation, 3 days pre-surgery, 1 week and either 8 or 16 weeks post-amputation.

Results: Across the two amputation ages, results indicated that tail amputation induced a significant reduction (P<0.05) in mechanical nociceptive thresholds in short and long tails one week after surgery. The same treatment effect was observed at 16 weeks after amputation performed at 9 weeks of age (P<0.05). For surgeries performed at 17 weeks of age, thresholds tended to be lower in short compared to intact tails (P=0.081) and significantly lower (P<0.05) in long tail pigs 8 weeks after amputation. No significant difference was observed at 16 weeks following surgeries performed at 17 weeks of age.

Conclusion: These results show that surgical amputation of pig tails leads to decreased cutaneous mechanical nociceptive thresholds in the skin area proximal to the site of injury. Results indicated that severe tail injury occurring in the weaner period may be associated with sensitisation up to 16 weeks following the injury. In contrast, injuries occurring in the finishing period appeared to be associated with shorter lasting mechanical sensitisation, resolving within 16 weeks.

Poster Di Giminiani IPVS

 

FareWellDock Edinburgh Satellite Meeting

Meeting, Pigs, Tail docking, , , ,

On July 12th the FareWellDock consortium hosted a satellite meeting and videoconference at the Roslin Institute Building near Edinburgh to coincide with the 50th conference of the International Society for Applied Ethology. The aim of the satellite meeting was to invite researchers involved in other European projects on tail docking and biting to share their work and ideas with the consortium.

The speakers gave four excellent presentations which generated interesting discussions and more ideas for planning future work (see brief summaries below)

Updates of the three work packages were also presented at the meeting. Since the last meeting in March, several more articles on tail docking and biting have been published and a number are near completion. Work progress in all three work packages appears to be on track.

Emphasis was placed upon generating and circulating draft fact sheets from the 3 work packages before the FVO Stakeholder Meeting in Grange, Republic of Ireland on October 4-6th 2016.

Sabine Dippel, a researcher at the Federal Research Institute of Animal Health (FLI), provided a comprehensive overview of “Current tail biting projects in Germany” and the summarised outputs from 51 different projects ranging from those focussed on basic science to feasibility and survey-based studies. Preliminary findings suggested that:
• Undocked weaner pigs were at higher risk of tail biting than undocked fattening pigs.
• Farmers need to gain experience in observing pigs
• Farms need to change step-by-step towards intact tails
• Focus on farm-individual optimisation
• Greater coordination between production stages
• Advice, training, knowledge transfer were essential to achieving these aims
Tail biting pigs
Valérie Courboulay a researcher at IFIP (French Institute for the pig and pork industry) provided an overview of several IFIP related studies on tail biting and dissemination of information in the form of technical datasheets to French farmers. Data presented from studies where pain relief (meloxicam) was provided at the time of docking and castration showed marginal affects on general behaviours, except for increased time spent sitting. When investigating tail posture, pigs with more severe tail lesions (score 3) exhibited more tail-down posture than pigs with minor tail or no tail lesions (score 2-0). A recent study has been undertaken to develop a model of cannibalism in pigs based on frustration of exploratory behaviours by providing environmental enrichment (progressive supply) and straw in the post weaning period and then some groups were reared with or without environmental enrichment for a short duration in the fattening period. The results showed that:
• Removal of enrichment between the post weaning and fattening periods is not sufficient to induce tail biting
• Providing objects for a few days and removing them is not sufficient to induce tail biting
• Frustration of investigative behaviour, that is considered as a major risk factor, is not sufficient to induce tail biting

INRA factsheet on pain

Jen-yun Chou, a first year PhD student working at Teagasc in the Republic of Ireland, presented preliminary findings from her studies into the use of wood as a strategy to reduce the risk of tail biting in pigs managed on slatted floors. The potential use of wood as a manipulable material is viewed positively in Irish production systems due to the problems of slurry removal caused by loose straw in fully slatted systems. To date, preliminary data have shown that softwoods such as spruce and scots pine are more readily used by the pigs compared to more hardwoods such as larch and beech.
• Spruce was used up most quickly both in terms of length and weight loss, possibly due to its softness.
• There is a tendency of more interaction with the wood by pigs in pens provided with spruce.
• In terms of texture and moisture spruce is a good option for enrichment but the cost may be a drawback
• Different wood types did not affect harmful behaviours, pig physical measures and production.
• Correlation between ear lesion and tear staining scorings implies a potential welfare assessment method on farm due to easy visibility.
• Correlation between tail posture and lesion shows that posture could be an indicator of tail biting

Chewed wood

Anna Sinclair, a first year SRUC PhD student currently working at the Institut National de la Recherché Agronomique (INRA), presented preliminary findings from studies into the behavioural and neural/cellular consequences of tooth resection in commercial pigs at its implications for pig welfare. Although this work was not directly related to tail docking or biting it is a project that was developed through on-going collaborative research by Dr. Armelle Prunier ay INRA and Dr. Dale Sandercock at SRUC within the FareWellDock project, addressing the issue of early life pain in livestock. Preliminary data were presented on the effects of tooth clipping and tooth grinding on tooth length and tooth/gum injury, haematological measures, live weight/growth rates, general, stress and pain related behavioural measures. Findings to date have shown that:
• Tooth damage was readily observed but variable
• Maxillary incisors are most consistently affected
• Clipping results in tooth and gum bleeding
• Growth rates are unaffected
• Pigs exhibit reduced activity after tooth treatments
• Pigs keep their ears back less and their tails down more, although this could be handling effect
• High variation at this stage – more data are required

Tooth treatment

Application of a handheld Pressure Application Measurement device for the characterisation of mechanical nociceptive thresholds in intact pig tails

Pigs, Tail docking, , , ,

Application of a handheld Pressure Application Measurement device for the characterisation of mechanical nociceptive thresholds in intact pig tails. By Pierpaolo Di Giminiani, Dale A. Sandercock, Emma M. Malcolm, Matthew C. Leach, Mette S. Herskin and Sandra A. Edwards. 2016. Physiology & Behavior 165: 119–126.

Highlights

• Mechanical nociceptive thresholds were quantified for the first time in pig tails.
• The PAM device allowed determining anatomical and age-specific thresholds in pigs.
• A platform for the assessment of painful conditions in pigs is proposed.

Abstract

The assessment of nociceptive thresholds is employed in animals and humans to evaluate changes in sensitivity potentially arising from tissue damage. Its application on the intact pig tail might represent a suitable method to assess changes in nociceptive thresholds arising from tail injury, such as tail docking or tail biting. The Pressure Application Measurement (PAM) device is used here for the first time on the tail of pigs to determine the reliability of the methods and to provide novel data on mechanical nociceptive thresholds (MNT) associated with four different age groups (9, 17, 24 and 32 weeks) and with proximity of the target region to the body of the animal. We recorded an overall acceptable level of intra-individual reliability, with mean values of CV ranging between 30.1 and 32.6%. Across all age groups, the first single measurement of MNT recorded at region 1 (proximal) was significantly higher (P b 0.05) than the following two. This was not observed at tail regions 2 and 3 (more distal). Age had a significant effect (P b 0.05) on the mean thresholds of nociception with increasing age corresponding to higher thresholds. Furthermore, a significant effect of proximity of tail region to the body was observed (P b 0.05), with MNT being higher in the proximal tail region in pigs of 9, 17 and 24 weeks of age.
There was also a significant positive correlation (P b 0.05) between mechanical nociceptive thresholds and age/body size of the animals.
To the best of our knowledge, no other investigation of tail nociceptive thresholds has been performed with the PAM device or alternative methods to obtain mechanical nociceptive thresholds in intact tails of pigs of different age/body size. The reliability of the data obtained with the PAM device support its use in the measurement of mechanical nociceptive threshold in pig tails. This methodological approach is possibly suitable for assessing changes in tail stump MNTs after tail injury caused by tail docking and biting.

Histopathological Characterization of Tail Injury and Traumatic Neuroma Development after Tail Docking in Piglets

Pigs, Tail docking, , ,

Histopathological Characterization of Tail Injury and Traumatic Neuroma Development after Tail Docking in Piglets. By: D.A. Sandercock, S.H. Smith, P. Di Giminiani, S.A. Edwards, 2016. Journal of Comparative Pathology 155: 40-49.

Abstract

Tail docking of neonatal pigs is widely used as a measure to reduce the incidence of tail biting, a complex management problem in the pig industry. Concerns exist over the long-term consequences of tail docking for possible tail stump pain sensitivity due to the development of traumatic neuromas in injured peripheral nerves. Tail stumps were obtained post mortem from four female pigs at each of 1, 4, 8 and 16 weeks following tail amputation (approximately two-thirds removed) by a gas-heated docking iron on post natal day 3. Tissues were processed routinely for histopathological examination. Non-neural inflammatory and reparative epidermal and dermal changes associated with tissue thickening and healing were observed 1 to 4 months after docking. Mild neutrophilic inflammation was present in some cases, although this and other degenerative and non-neural reparative changes are not likely to have caused pain. Traumatic neuroma and neuromatous tissue development was not observed 1 week after tail docking, but was evident 1 month after tail docking. Over time there was marked nerve sheath and axonal proliferation leading to the formation of neuromata, which were either localized and circumscribed or comprised of multiple axons dispersed within granulation tissue. Four months after tail resection, neuroma formation was still incomplete, with possible implications for sensitivity of the tail stump.

Corrigendum to “Histopathological Characterization of Tail Injury and Traumatic Neuroma Development after Tail Docking in Piglets” J Comp Pathol 155 (1) (2016) 40-49.

The authors wish to clarify terminology used in their paper entitled ‘Histopathological characterization of tail injury and traumatic neuroma development after tail docking in piglets’ and thank the Editor for the opportunity to do so. In the absence of a specific immunohistochemical label for detection of axons, the words ‘axon/axonal’ were inaccurately used and should be replaced by ‘Schwann cell’. Without more specific proof, it
certainly does not confirm, or necessarily infer, conduction. Secondly, ‘S100 neurofilament’ was inadvertently used instead of simply ‘S100’. The authors apologise for this error, which was wholly editorial on their part. Finally, in our opinion, the literature definitions of traumatic neuromas are such that there is likely to be some disagreement as to their required component features, particularly at different stages of lesion development, in different species and in different age groups of animals. In our paper, descriptions of traumatic neuroma presence and development were also based on haematoxylin and eosin staining and not solely confined to S100 immunolabelling. To this end, features such as variably-sized microfascicles, disorderly (often circumferential) neural proliferation and nerve fibres turning back on themselves are consistent with previous reports on traumatic neuromas in a number of species, including pigs.
While the aforementioned errors are regretted, this work was intended as a descriptive morphological characterization of a wide range of histopathological changes over known time points post docking. We have had some criticism that, due to our use of the word axonal, we have implied or claimed innervation, and thus pain sensation,
during the weeks after docking. This was not our intention – rather, our opinion is neutral in terms of whether or not traumatic neuromas are painful. The last sentence of the paper acknowledged that this work could not determine that. This study was considered descriptive and foundational, to serve as a platform for further investigation.
Its take-home message, irrespective of the error in terminology, is that neural proliferation consistent with traumatic neuroma development appears to be still ongoing at 16 weeks after tail docking.

Investigating the effect of rooting substrate provision on the group lying behaviour of pigs using machine vision

Enrichment, Pigs, , ,

Investigating the effect of rooting substrate provision on the group lying behaviour of pigs using machine vision. By: Abozar Nasirahmadi, Sandra A Edwards, Barbara Sturm,
Conference Paper · June 2016. Conference: CIGR-AgEng Conference, Aarhus, Denmark

Abstract

To deliver good animal welfare, pigs should have a hygienic and undisturbed lying area within the pen. However, the provision of a rooting material is desirable to meet behavioural needs and this can only be given onto solid floor away from the dunging area, which might disrupt the group lying pattern. To determine whether daily provision of a rooting material (maize silage) onto a solid plate in the lying area of a fully slatted pen resulted in changed lying location, the lying patterns of pigs in 6 enriched pens were compared with those of 6 control pens which had only a suspended enrichment toy. Since visual monitoring of pig behaviours over long periods is very time consuming, an image
processing technique was applied to identify any changes pig lying positions and behaviour. Pigs were monitored by top view CCTV cameras and animals were extracted from their background using image processing algorithms. The x–y coordinates of each binary image were used for ellipse fitting algorithms to localize each pig. In order to find the lying positions, ellipse parameters were calculated for all fitted ellipses. Each pen was virtually subdivided into four zones in images and the centroid of each fitted ellipse was used for finding the position of each lying pig at 10 minute intervals during their lying period, after use of an algorithm to remove images in motion preceding the scan. By means of the ellipse properties it was possible to automatically find and compare the
changes in lying position of pigs in the pens. Results showed that once daily provision of rooting material did significantly change lying behaviour.

Omnivores Going Astray: A Review and New Synthesis of Abnormal Behavior in Pigs and Laying Hens

Pigs, Tail biting, ,

Omnivores Going Astray: A Review and New Synthesis of Abnormal Behavior in Pigs and Laying Hens, by Emma I. Brunberg, Bas Rodenburg, Lotta Rydhmer, Joergen B. Kjaer, Per Jensen and Linda J. Keeling. Front. Vet. Sci., 22 July 2016.

Abstract

Pigs and poultry are by far the most omnivorous of the domesticated farm animals and it is in their nature to be highly explorative. In the barren production environments, this motivation to explore can be expressed as abnormal oral manipulation directed toward pen mates. Tail biting (TB) in pigs and feather pecking (FP) in laying hens are examples of unwanted behaviors that are detrimental to the welfare of the animals. The aim of this review is to draw these two seemingly similar abnormalities together in a common framework, in order to seek underlying mechanisms and principles. Both TB and FP are affected by the physical and social environment, but not all individuals in a group express these behaviors and individual genetic and neurobiological characteristics play an important role. By synthesizing what is known about environmental and individual influences, we suggest a novel possible mechanism, common for pigs and poultry, involving the brain–gut–microbiota axis.

Proper enrichment for intensively-farmed pigs – From review to preview

Enrichment, Legal, Pigs, Policy, Straw, Tail biting, Tail docking, , , ,

Bracke, M.B.M. 2016. Enrichment materials for intensively-farmed pigs – From review to preview (Conference abstract & presentation, ICPD 2016). In: Kemp, B. et al., 2016. 16th International Conference on Production Diseases in Farm Animals. June 20-23, 2016. Wageningen, NL. p. 179.

Abstract

Tail biting is a well-known production disease in intensively-farmed pigs raising concern for animal welfare, e.g. related to the practice of routine tail docking. To reduce tail biting pigs are provided with enrichment materials. EU legislation requires that pigs have permanent access to a sufficient quantity of material to enable proper investigation and manipulation activities. In order to meet this directive many pigs are provided with a metal chain with or without a rather indestructible object attached to the chain. The European commission recently revised current guidelines as to what constitutes adequate enrichment, apparently moving into the direction of the status-quo in welfare schemes. Building on extensive previous work at Wageningen UR Livestock Research, especially on the modelling of pig enrichment (the so-called RICHPIG model) a review is presented of our current state of knowledge. In addition, an outline is given as to how so-called AMI-sensors, measuring Animal-Material Interactions (AMI) (semi-)automatically, can be used to assess the pig’s need for enrichment, also in relation to aspects associated with health status, such as feed restriction, biting wounds and streptococcus infection. It is suggested that the use of chains with or without rather indestructible materials such as pipes, balls or (hard)wood is generally inadequate to enrich the pens of intensively-farmed pigs. An evolutionary mechanism appears to be underlying the causation of multifactorial welfare problems in general, the issues of enrichment, tail biting and tail docking in pigs in particular. In this respect ongoing selection for increased resource efficiency has been exerting a profound impact on livestock production. Various routes are explored as to how persistent welfare problems may be resolved, including a method that has been called Intelligent Natural Design (IND).

Branched chain
Two organic pigs interacting simultaneously with a branched chain in the snow. Despite access to a straw bed for rooting, even organic pigs may interact with such chains for long periods of time, esp. directed towards the floor. In fact they will root the chain on the floor more than twice as much as playing with it in a horizontal position. In intensive pig production chains are often (too) short, and when a hockey-type ball or ‘sustainable’ plastic pipe is attached to the end of such a chain the pigs’ interest, and their welfare, is often even reduced further. By contrast, to improve the chain further 7mm stainless-steel anchor chains may be recommended for growing pigs over the cheaper c-chain shown here, as anchor chains have heavier and more rounded shackles.

See also an older previous presentation on tail biting.

Bracke, M.B.M, Wolthuis, M., Zonderland, J. J., Kluivers, M., 2011. TAILS TO TELL – Tail docking, tail biting and enrichment for pigs – Experiences from the Netherlands. Herning, DK, May 25-26, 2011.