Tag Archives: pain

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

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.

Reducing mutilations in the European Union

A study on reducing the number of mutilations on animals within the European Union
By Sanne van Zanen (Student Wageningen University, email: sanne . vanzanen @ wur . nl)
Commissioned by the Ministry of Economic Affairs, the Netherlands

Abstract

This study has gathered information about the possibilities to reduce the number of mutilations throughout the European Union. It has focused on surgical castration of male pigs, tail docking of pigs and beak trimming of laying hens. According to literature, these mutilations have received most attention in the European Union. Furthermore, in most of the European member states these mutilations are frequently carried out. The study is performed by a graduate student of Wageningen University and commissioned by the Ministry of Economic Affairs. The conclusions of this study do not necessary reflect the official opinion of the Ministry of Economic Affairs.

This study started off with a desk research that sketched the concept of animal welfare across the European Union. A framework of factors that influence the importance attached to animal welfare resulted from this research and was used to clarify the results of the two additional studies within the broad concept of animal welfare across the European Union. The two additional studies that were performed are a literature study and a questionnaire. The literature study has focused on retrieving in-depth information on the current situation of the member states regarding the three mutilations. The questionnaire was set up to get insights into which actions have the greatest chance of success and what are the biggest obstacles in reducing the number of mutilations in animals. The questionnaire was spread, by means of an introducing email, to scientific researchers, veterinarians, policy
makers/officers, NGO’s, employees in a slaughterhouse, farmers and students across the European Union. In total 130 respondents filled out questions about at least one of the three mutilations across 16 member states (Cyprus, Bulgaria, Greece, Luxembourg, Latvia, Czech Republic, Hungary, Estonia, Lithuania, Malta, Romania and Slovenia have not taken part in the questionnaire).

United Kingdom, Ireland, Spain and Portugal nearly raise all their pigs as entire boars. In contrast to these countries, surgical castration of male pigs is the most desired option for the Italian pig market (and parts of the Spanish and Portuguese pig production). This is due to the restrictions imposed by the Parma ham industry (slaughtering pigs at
heavy weights). Consequently, the restrictions imposed by the Parma Industry and the sensitivity for boar taint are the biggest obstacles for reducing surgical castration for the Mediterranean countries. The Eastern European and Central European region do also nearly all surgically castrate their pigs and consider the restrictions imposed by the
Parma Industry and or boar taint sensitivity as an obstacle. The Northern European and Scandinavian regions have already made some efforts on reducing the number of practices by means of non-legislative initiatives. However, the biggest problem for realizing a complete stop of these regions and an additional problem of the Central and Eastern European regions is related to the absence of (inter)national acceptance of non-castrated pigs or immunocastrated pigs, which is crucial for these exporting countries. Consequently, on-line detection methods on the slaughter line of boar taint is of high importance. A legislative approach by the national government is seen by each geography region as the most successful factor for reducing the number of surgical castrated pigs, except central European region (remains unknown).

Tail docking of pigs is forbidden by national law in Sweden, Finland and Lithuania. The remaining Northern European countries do carry out this procedure on pigs, but an increasing number of legislative and non-legislative initiatives within this region show the urgency of phasing out this mutilation. The other European regions raise also pigs with docked tails, but no active initiatives could be found that aim for a reduction of this procedure. These regions consider a lack of political interest and or consumer willingness to pay for more animal friendly products as obstacles for realizing a reduction. Moreover, each region thinks of the following animal production related factors: large stocking densities of groups of pigs, floor type of housing system used and absence and or insufficient enrichment as likely being a restriction in order to realize a reduction of tail docking. A legislation approach by the national government is the most successful factor for realizing a reduction. The Central European region is an exception, because they consider a wholesale price increase by national retailers as most successful.

Beak trimming of laying hens, is already forbidding in Sweden, Finland, Austria and Denmark either by means of national legislation or as a voluntary ban by the poultry sector. Legislative and non-legislative initiatives aim for a stop in the near future or a reduction of beak trimming within the Northern European region. The other regions do
not show a sense of urgency for reducing beak trimming of laying hens. A lack of willingness to pay of consumers and political interest are seen as obstacles for reducing beak trimming within these regions. Furthermore, it seems that the husbandry systems of these regions are not ready yet to raise hens with intact beaks, because large stocking densities, breed and the housing system used are seen as the most frequent additional obstacles. A legislation approach by the national government is the factor with the greatest chance of realizing a reduction of beak trimming for most of the regions (Northern- and Eastern European regions remain unknown). The central European region considers the influence of large multinationals as most successful. Furthermore, the questionnaire results of the Eastern European region could not be used, it is expected that this region is not ready (yet) to reduce the number of beak trimming procedures.

See also Initiatives to reduce mutilations in EU livestock production. By Spoolder, H.A.M.; Schone, Maria; Bracke, M.B.M. 2016. Report 940. Wageningen Livestock Research, Wageningen.

Docking a piglet's tail using cautery (hot iron)

Executive summary

Which of the European member states have the potential to join the four front-runners?

The European member states that have the potential to become a coalition partner of the Netherlands, Germany, Denmark and Sweden to reduce surgical castration of male pigs, tail docking of pigs and beak trimming of laying hens within the European Union.

Thesis
S.E.J. van Zanen
March 11, 2016
Adaptation Physiology Group
Wageningen University & Ministry of Economic Affairs

In order to get animal welfare higher on the European agenda The Netherlands, Germany and Denmark reached an agreement on several animal welfare related mutilations in 2014. Sweden joined the trilateral agreement in 2015. It is expected that by means of a joint European approach the biggest win for improving animal welfare can be reached within the European context. The main research question in this study is: which European member states have the potential to become a coalition partner of the Netherlands, Germany, Denmark and Sweden in order to reduce surgical castration procedures in male pigs, tail docking procedures in pigs and beak trimming procedures
in laying hens? Other research questions are about the influence of the individual member states in the European Union and the key success factors and the biggest obstacles in realizing a reduction of each of the three mutilations within several geographic regions.
This study starts with a desk research that sketches the concept of animal welfare across the European Union. The result is a framework of factors that influences the importance attached to animal welfare and is used to explain the results of the following two studies within the broad concept of animal welfare across the European Union. A second desk research focuses on retrieving in-depth information on the current situation of the member states regarding the three mutilations. Thirdly, a questionnaire was set up to get insights into which actions have the greatest chance of success and what are the biggest obstacles in reducing the number of mutilations in animals. The questionnaire was spread, by means of an introducing email, to scientific researchers, veterinarians, policy makers/officers, NGO’s, employees in a slaughterhouse, farmers and students across the European Union. In total 130 respondents filled out questions about at least one of the three mutilations across 16 member states (Cyprus, Bulgaria, Greece, Luxembourg, Latvia, Czech Republic, Hungary, Estonia, Lithuania, Malta, Romania and Slovenia have not taken part in the questionnaire). Germany, France, Italy and the United Kingdom are the most influential member states within the European Union. Furthermore, these member states, together with the Netherlands, Denmark, Spain and Poland are the biggest egg and pig producing states and or the greatest exporting countries of pork meat.
A legislative approach by the national government is seen by each geographical region as the most successful factor for reducing the number of surgical castrated pigs, except the central European region (remains unknown).
The majority of the pigs raised in the United Kingdom, Ireland, Spain and Portugal are entire boars. In contrast to these member states, the restrictions imposed by the Parma ham industry force the Italian pig market (and small parts of the Spanish and Portuguese pig production) to slaughter their pigs at heavy weights, which makes surgical castration the most desired option. Consequently, the restrictions imposed by the Parma Industry and the sensitivity for boar taint are the biggest obstacles for reducing surgical castration for the Mediterranean region. The Eastern European and Central European region do also nearly all surgically castrate their pigs and consider the restrictions imposed by the Parma Industry and or boar taint sensitivity as an obstacle(s). The Northern European and Scandinavian regions have already made some efforts on reducing the number of surgical castration practices by means of non-legislative initiatives. However, the biggest problem for realizing a complete stop in these regions (and an additional problem of the Central and Eastern European regions) is related to the absence of (inter)national acceptance of non-castrated pigs or immunocastrated pigs, which is crucial for these exporting countries. Consequently, on-line detection methods on the slaughter line of boar taint is of high importance. It is suggested that the United Kingdom has the highest potential to be a coalition partner of the Netherlands, Germany, Denmark and Sweden in order to reduce the number of surgical castrated pigs within the European Union.
The majority of the geographic regions consider a legislation approach by the national government as the most successful factor for realizing a reduction of tail docking of pigs. The Central European region is an exception, because they think of a wholesale price increase by retailers as most successfull. Tail docking of pigs is forbidden by national law in Sweden, Finland and Lithuania. The Northern European region does carry out this procedure on pigs, but an increasing number of legislative and nonlegislative initiatives within this region show the urgency of phasing out this mutilation. The other European regions raise also pigs with docked tails, but no active initiatives could be found that aim for a reduction of this procedure. These regions consider a lack of political interest and or consumer willingness to pay for more animal friendly products as obstacles for realizing a reduction. Moreover, each region considers large stocking densities of groups of pigs, floor type of housing system used and absence and or insufficient enrichment as animal-production based obstacles for realizing a reduction of tail docking. It is expected that Finland has the highest potential to be a coalition partner of the Netherlands, Germany, Denmark and Sweden in order to reduce the number of tail docking procedures in pigs within the European Union.
The Mediterranean region considers a legislative approach by the national government as the factor with the greatest chance of success in realizing a reduction of beak trimming procedures (Northern- and Eastern European regions remain unknown). The Central European region considers the influence of large multinationals as most successful. Furthermore, the questionnaire results of the Eastern European region could not be used, it is expected that this region is not ready (yet) to reduce the number of beak trimming procedures. Beak trimming of laying hens is already forbidding in Sweden, Finland, Austria and Denmark either by means of national legislation or as a voluntary ban by the poultry sector. Legislative and non-legislative initiatives aim for a stop in the near future or a reduction of beak trimming procedures within the Northern European region. The other regions do not show a sense for urgency of reducing beak trimming of laying hens. A lack of willingness to pay of consumers and political interest are seen as obstacles for reducing beak trimming within these regions. Furthermore, the husbandry systems of these regions are not ready yet to raise hens with intact beaks, because large stocking densities, breed and the housing system used are seen as the most frequent additional obstacles. Austria and Finland are suggested to have the highest potential to be coalition partners of the Netherlands, Germany, Denmark and Sweden in order to reduce the number of beak trimming procedures in laying hens within the European Union.

Effects of tail docking and docking length on neuroanatomical changes in healed tail tips of pigs

Effects of tail docking and docking length on neuroanatomical changes in healed tail tips of pigs
By M. S. Herskin, K. Thodberg and H. E. Jensen. 2015. Animal 9: 677-681.

Abstract

In pig production, piglets are tail docked at birth in order to prevent tail biting later in life. In order to examine the effects of tail docking and docking length on the formation of neuromas, we used 65 pigs and the following four treatments: intact tails (n=18); leaving 75% (n=17); leaving 50% (n=19); or leaving 25% (n=11) of the tail length on the pigs. The piglets were docked between day 2 and 4 after birth using a gas-heated apparatus, and were kept under conventional conditions until slaughter at 22 weeks of age, where tails were removed and examined macroscopically and histologically. The tail lengths and diameters differed at slaughter (lengths: 30.6±0.6; 24.9±0.4; 19.8±0.6; 8.7±0.6 cm; P<0.001; tail diameter: 0.5±0.03; 0.8±0.02; 1.0±0.03; 1.4±0.04 cm; P<0.001, respectively). Docking resulted in a higher proportion of tails with neuromas (64 v. 0%; P<0.001), number of neuromas per tail (1.0±0.2 v. 0; P<0.001) and size of neuromas (1023±592 v. 0 μm; P<0.001). The results show that tail docking piglets using hot-iron cautery causes formation of neuromas in the outermost part of the tail tip. The presence of neuromas might lead to altered nociceptive thresholds, which need to be confirmed in future studies.

Influence of tail docking, with or without a cold analgesic spray, on behaviour, performance and physiology of piglets

Influence of tail docking, with or without a cold analgesic spray, on behaviour, performance and physiology of piglets
By Armelle Prunier, Gaëlle Bataille, Marie-Christine Meunier-Salaün, Aline Bregeon, Y. Rugraff. 2001. Journées Rech. Porcine en France, 33, 313-318. (Article in French).

Abstract

Tail docking performed in order to avoid tail biting in fattening pigs is criticized. In order to assess its short term consequences, two experiments were realized. The first one performed on 160 piglets from 32 litters was focussed on the behavioural consequences and the growth performance. The aim of the second one was to determine the effects of tail docking on the adrenal (plasma cortisol and ACTH) and sympathetic (measurement of glucose and lactate released from catecholamine-induced mobilization of glycogen) axes in 20 piglets from 7 litters which were catheterized at birth. In the first experiment, there were 5 treatments: tail docking, tail docking + a cold analgesic spray, control handling, control handling + spray, no handling. In the second experiment, the same treatments were run, except the fourth one. Treatments were applied the day after birth and tail was docked with an iron docking (cautery). During treatment, tail docking caused more movements (legs and/or body) and howls (P < 0.05). During the 20 s following treatment, docked piglets demonstrated more tail jamming and wagging (P < 0.05). Both types of docking consequences were attenuated when the cold spray was used. During the following 12 hours, time spent by the piglets to rest or to be active at the sow udder was similar in the 5 groups. Growth rate during the first week of life and the occurrence of injuries at the tail did not differ between groups (P > 0.1). Tail docking with or without the cold spray had no marked effects on the patterns of plasma cortisol, ACTH, glucose and lactate. In conclusion, tail docking causes probably pain of moderate amplitude.

Impact of tail docking on behaviour of suckling piglets

Impact of tail docking on behaviour of suckling piglets
by Céline Tallet, Marine Rakotomahandry, Sabine Herlemont, Armelle Prunier, 2016. Journées Recherche Porcine, 48, 235-236 (Article in French).

Abstract

Tail docking is still applied in Europe to prevent tail biting, despite its evident negative impact on pig welfare. We aimed at characterising consequences of tail docking on suckling piglets. We compared 48 piglets with tail docked (C) to 50 undocked piglets submitted to a non-painful simulation of docking (S). Their behavioural reaction during docking and for 20 s following the process was observed: vocalisations, tail posture and movements. Observations were repeated on C animals and on 48 other animals left intact from birth (I), 4 h after the docking process, 3 days after and once a week, in addition giving a score to the state of the tail. Fifteen days after birth, their reaction to a motionless seated human was observed. The C piglets vocalised more and louder during the docking process than S piglets (P < 0.05). For the 20 s after docking, their tail remained immobile longer (P < 0.05). The tail was also more immobile during the whole suckling period (P < 0.05). The C piglets approached the unfamiliar human later than the I piglets (P < 0.05). The I piglets tended to have more tail lesions than the C group (P < 0.1) during suckling. Tail docking thus induces reactions indicating pain on the day of docking and throughout the suckling period. Evidence of first episodes of tail biting were also found in I pigs. Longer term effects remain to be characterised (pain and bitings).

Impact of straw on gastric ulceration in pigs

Impact of the amount of straw provided to pigs kept in intensive production conditions on the occurrence and severity of gastric ulceration at slaughter.
Herskin MS, Jensen HE, Jespersen A, Forkman B, Jensen MB, Canibe N, Pedersen LJ. 2016. Res Vet Sci. 104: 200-6.

Abstract

This study examined effects of the amount of straw offered on occurrence and severity of gastric lesions in pigs kept in pens (18 pigs, 0.7m(2)/pig) with partly slatted flooring and 10, 500 or 1000g straw/pig/day from 30kg live weight. The pigs had ad libitum access to dry feed. Forty-five pigs were used, three from each of 15 pens. After euthanisia, the dimension of the non-glandular region of the stomach was measured. Lesions were characterized and scored. Irrespective of straw provided, 67% of the pigs showed signs of gastric pathology. Pigs provided with 500 or 1000g straw were pooled as ‘permanent access’. The proportion of pigs with ulcerations was reduced by permanent access to straw (7 vs. 33%; P<0.05), suggesting that permanent access to straw may improve animal health, and be considered as one possible strategy to limit gastric ulceration in pigs.

500gr straw/pig/day
500gr straw/pig/day
10gr straw/pig/day
10gr straw/pig/day

Penile injuries (incl. penis biting) in domestic (& wild) pigs

Penile Injuries in Wild and Domestic Pigs.
By Weiler U, Isernhagen M, Stefanski V, Ritzmann M, Kress K, Hein C, Zöls S. 2016. Animals 6: 4.

Abstract

In boars, sexually motivated mounting can not only cause problems such as lameness, but penile injuries are also reported. The relevance of penis biting in boars is discussed controversially, but reliable data is missing. In the present study, boars ( n = 435) and barrows ( n = 85) from experimental farms were therefore evaluated for scars, fresh wounds and severe injuries of the penis. Similarly, 321 boars from 11 farms specializing in pork production with boars, and 15 sexually mature wild boars from the hunting season of 2015/16 were included in the study. In domestic boars, a high incidence of penile injuries was obvious (76.6%-87.0% of animals with scars and/or wounds at experimental farms, 64.0%-94.9% at commercial farms). The number of boars with severe injuries was in a similar range in both groups (7.3% vs. 9.3%). At commercial farms, the number of scars but not that of fresh wounds increased per animal with age by 0.3 per week. Moreover, raising boars in mixed groups led to about a 1.5 times higher number of scars than in single-sex groups. In wild boars, a considerable proportion of animals (40%) revealed penile injuries, which were even severe in three animals. We therefore conclude that penis biting is a highly relevant and severe welfare problem in the male pig population, but this phenomenon is not limited to intensive production systems.

Notes:
In commerical pig production penis biting is a problem of intact boars. The examined barrows were all free of scars, wounds, severe injuries or suppuration.
For pictures of just how severe penis biting in pigs can be see the article Penisbeissen ein blutiges Phanomen in der Ebermast.

Histological and neurophysiological pain assessment in young pigs

Original title: Approche histologique et neurophysiologie de la douleur liée à la coupe de queue chez les porcelets

Presentation of Dr. Dale Sandercock (SRUC) at a seminar on histological and neurophysiological approaches to pain assessment in young pigs. INRA-PEGASE, St-Gilles, France, December 14th 2015

Abstract

Concerns exist over the long term consequences of tail docking on possible tail stump pain sensitivity due to the development of traumatic neuromas in injured peripheral nerves. Traumatic neuroma formation may cause detrimental sensory changes in the tail due to altered peripheral and spinal neuronal excitability leading to abnormal sensation or pain. We have investigated tail injury and traumatic neuroma development by histopathological assessment after tail docking and measured the expression of key neuropeptides associated with peripheral nerve regeneration, inflammation and chronic pain. In complimentary studies on tail docking and tail biting, we have developed behavioural assessment approaches to measure mechanical nociceptive thresholds (MNT) in the pig tail in purpose built test set-up using a Pressure Application Measurement (PAM) device. Using these approaches we have determined baseline MNT in intact tails along different regions of the tail and also measured changes in MNT over time in pig with resected tails (simulation of the effect of tail biting). An overview of other Scotland’s Rural College (SRUC) pig health and welfare research projects is also presented.

Presentation Pic INRA seminar on pain (D Sandercock, 2015))

News from The Netherlands (and Germany)

This first week of February 2016 two items related to tail biting appeared in farmers’ press in The Netherlands. In addition, we recently provided input into a European project on the welfare of poultry, which will be reported on briefly below.

One news item announced that farmers are invited at the Intensive Farming Fair in Venray (LIV Venray), March 1-3 2016. At the fair two finished tail-biting projects will be presented and discussed with entrepreneurs who are active in intensive farming. One of the projects is ‘Keeping pigs with intact tails’.

The other item was a report on the German tail biting (Ringelschwanz-)project. First results of the curly-tail project in North-Rhine Westphalia showed that more than one quarter of piglets at 15 participating research farms had damaged tails before the end of the rearing period. At some farms half of the tails had been bitten. At the 15 farms participating in the study 30-94 piglets had been reared on each farm without tail docking. Outbreaks of tail biting appeared to be associated with streptococcus infections. Prevention and intervention strategies included providing dried maize silage or alfalfa hay twice daily and the isolation of biters respectively. Most tail biting occurred between week 2 and 4 after weaning. This level of tail biting is not so good news. If these levels of tail biting would persist, it may indicate that intensive systems cannot be made compatible with acceptable levels of animal welfare. Fortunately, however, experiences in Finland indicate that it should be possible to keep undocked pigs in conventional systems at much lower levels of tail biting (around 2% based on slaughter house data).

The German farmers union and North-Rhine Westphalia have agreed 1.5 years ago that they intend to stop tail docking by 2017. This will be done provided on-farm research shows that tail biting among pigs with intact tails does not reduce animal welfare. The general expectation is that the objective of safely quitting tail docking cannot be met.

From a Dutch research perspective two notes appear to be relevant:

The first is that our semantic-modelling approach provides a unique methodology to determine/assess  the cut-off point between the welfare impacts of tail biting and tail docking using formalised biological reasoning and scientific evidence. In this computation one must take into account all relevant aspects: So, not only the point that the welfare of tail bitten pigs is reduced due to blunt trauma (biting) compared to the sharp trauma of tail docking at an earlier age. But also the point must be recognised that the welfare of tail biting pigs may relatively be improved when they can bite their penmates’ tails, compared to when they cannot (other things being equal, i.e. lack of suitable enrichment). What matters for welfare as considered from the animals’ point of view is the extent to which they can satisfy their needs, e.g. for biting and the expression of species-specific foraging behaviour, taking into account also the activation of coping mechanisms such as redirected and harmful-social behaviours.

The second thing to note about the results of the German research project is the following. In addition to taking note of the bad news (many bitten tails, which has to be taken seriously, perhaps even to the point that the conclusion must be drawn that intensive systems are not compatible with acceptable animal welfare), one may also try to move forwards for the time being by focussing on the good news: Two out of the 15 pilot farms in Germany managed to keep all piglets’ tails intact. Other farms may learn from what was done on these farms to keep tails intact. Furthermore, since the EC Directive requires that all farms try to periodically keep at least some intact pigs, a 10% success rate could provide sufficient scope for progress at the population level, even when the causes of the success are poorly understood. This can be concluded from a methodology we designed previously to solve complex welfare problems like feather pecking in poultry and tail biting in pigs. This methodology has been called ‘Intelligent Natural Design’ (INO in Dutch; see also Bracke, 2010). It basically uses evolution to select the best farms to make increasing progress towards the objective of completely stopping the practice of routine tail docking in pig farming.

Countering the routine practices of tail docking and beak trimming, as well as preventing and treating outbreaks of tail biting and feather pecking requires an understanding of tipping points. Recently, we modified our tipping-bucket model for tail biting for inclusion on the Henhub website. This website, which is part of the Hennovation project, gives information about welfare issues in poultry, esp. (at present) feather pecking. On that site the modified tipping-bucket model can be found under the post describing the mechanism of feather pecking.

Tipping-bucket model of tail biting in pigs
Tipping-bucket model of tail biting in pigs

.
Bracke, M.B.M. 2010. Towards long(er) pig tails: New strategy to solve animal welfare problems. In: Lidfors, L., Blokhuis, H., Keeling, L., Proceedings of the 44th Congress of the ISAE, August 4-7 2010, Wageningen Academic Publishers, Wageningen, p. 135. (Poster, ISAE 2010, Uppsala, Sweden, Aug 4-7.

Preliminary study on tail nerves in piglets after tail docking

Carr, R.W., J.E. Coe, E. Forsch, M. Schmelz, D.A. Sandercock, 2015. Structural and functional characterisation of peripheral axons in the caudal nerve of the neonatal pigs: Preliminary data. Proceedings of the 9th EFIC Congress, Vienna, Sept 2-5.

Summary

The pig tail is innervated by the caudal tail nerves and it is evident at the site of injury after tail docking (i.e. 8/9th caudal vertebrae) that a relatively high proportion of both C and A-fibres can be affected following peripheral nerve transection, with implications for axonal excitability and nociceptive processing in the tail stump.
As a proof of principle, it is possible to assess A- and C-fibre axonal function using electrical axonal excitability techniques for pig caudal tail nerve. In neonatal caudal nerves, A and C-fibre axons show significant changes in conduction speed which are related primarily to neonatal age.
Future studies will examine axonal functional properties in pig tails later in life where traumatic neuroma formation in the caudal nerves is present.

Annotated TEM micrograph of tail nerves (Dale Sandercock)

Abstract

Structural and functional characterisation of peripheral axons in the caudal nerve of the neonatal pigs: Preliminary data
R.W. Carr1, J.E. Coe2, E. Forsch1, M. Schmelz1, D.A. Sandercock2
1Department of Anaesthesiology, University of Heidelberg, Mannheim, Germany
2Animal and Veterinary Science Research Group, Scotland’s Rural College (SRUC), Easter Bush, United Kingdom

Background and aims: Early postnatal tail docking (amputation of 2/3rds of the tail) in piglets is performed as a preventative measure to minimize potential trauma associated with tail biting in older animals. The aim of this study was to investigate caudal nerve axonal composition and the effects of tail docking on axonal function in neonatal pigs.
Methods: Axonal composition was examined using Transmission Electron Microscopy (TEM). Functional assessment of A and C-fibre axons was performed in vitro using compound action potential (CAP) recordings from isolated nerve fascicles.
Results: TEM revealed both myelinated and unmyelinated axons in dorsal and ventral caudal nerves. Myelinated axons ranged in size from small diameter thinly myelinated Aδ-axons to larger diameter Aβ-axons (mean 2.30; range 0.7-6.3 μm). Unmyelinated C-fibre axons clustered together in multiple Remak bundles (mean 0.7; range 0.3-1.9 μm). Caudal nerves were harvested for functional assessment at 5 days of age from undocked tails and at 12.3 days (i.e. 9.3 days after docking) from docked pigs. The average A-fibre CAP amplitude from undocked tails was larger (1599.6±552.9μV) and conducted more rapidly (9.79±2.04m/s) than the A-fibres from docked tails (amplitude 1065.1±507.6μV and c.v.=7.78±2.57m/s). For C-fibres, the average axonal conduction velocity in docked tails was slower (1.74±0.2m/s) than in undocked tails (2.26±0.41m/s). Axonal conduction in caudal nerve C-fibres from both intact and docked animals was completely blocked by 500 nM tetrodotoxin (TTX) suggesting conduction was mediated primarily by TTX-sensitive NaV-isoforms.
Conclusions: As a proof of principle study, it is possible to functionally assess A- and C-fibre axons in pig caudal nerve using electrical axonal excitability techniques.
Acknowledgments: ANIWHA.

Poster Carr et al. 2015