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Rearing Pigs with Intact Tails—Experiences and Practical Solutions in Sweden

Wallgren, T., Lundeheim, N., Wallenbeck, A, Westin, R. and Gunnarsson, S. 2019. Rearing pigs with intact tails- experiences and practical solutions in Sweden. Animals 2019, 9, 812; doi:10.3390/ani9100812


Tail biting is a common issue within commercial pig production. It is mainly an indicator of inadequate housing environment and results in reduced health welfare and production. To reduce the impact of tail biting, pigs are commonly tail docked, without pain relief, within the first week of life. EU Council Directive 2008/120/EC prohibits routine tail docking, but the practice is still widely used in many Member States. Sweden has banned tail docking since 1988 and all pigs have intact tails, yet tail biting is a minor problem. This paper summarises and synthesises experimental findings and practical expertise in production of undocked pigs in Sweden and describes solutions to facilitate a transition to producing pigs with intact tails within intensive pig production in the EU. Swedish pig housing conditions and management differ in many aspects from those in other EU Member States. Swedish experiences show that lower stocking density, provision of sufficient feeding space, no fully slatted flooring, strict maximum levels for noxious gases and regular provision of litter material are crucial for success when rearing pigs with intact tails. To prevent tail biting and to eliminate the need for tail docking, we strongly recommend that EU legislation should more clearly match the biological needs of pigs, as is done in Swedish legislation.

Tail docking in pigs is an amputation causing sustained transcriptomic expression changes in the spinal cord indicative of inflammation and neuropathic pain

Transcriptomics Analysis of Porcine Caudal Dorsal Root Ganglia in Tail Amputated Pigs Shows Long-Term Effects on Many Pain-Associated Genes
By Dale A. Sandercock, Mark W. Barnett, Jennifer E. Coe, Alison C. Downing,
Ajit J. Nirmal, Pierpaolo Di Giminiani, Sandra A. Edwards and Tom C. Freeman.  Frontiers in Veterinary Science, September 2019 | Volume 6 | Article 314.


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.

PhD live stream: A tale of tails – prevention of tail biting in pigs by early detection and straw management. Torun Wallgren. Friday 20-9-2019, 09.15u, Sweden

Dissertation: Friday 20 September 2019, 09.15 in Audhumbla, VHC, SLU Ultuna

Torun Wallgren defends her thesis “A tale of tails – prevention of tail biting in pigs by early detection and straw management”. View the live stream / recording

Torun Wallgren: A tale of tails – Prevention of tail biting by early detection and straw management

Opponent /external evaluator: Professor Nicole Kemper, Institute for Animal Hygiene, University of Veterinary Medicine Hannover, Germany

Examination board:

Professor Andrew Michael Janczak, Norwegian University of Life Sciences (NMBU), Oslo, Norway

Agr. Dr. Anne-Charlotte Olsson, Inst för Biosystem och Teknologi, SLU Alnarp

Professor Lotta Rydhmer, Professor, Inst för Husdjursgenetik (HGEN), SLU Ultuna

Professor Linda Keeling, Institutionen för husdjurens miljö och hälsa (HMH), SLU Ultuna (reserv).


Docent Stefan Gunnarsson, HMH, SLU Skara

Assisting supervisors:

Nils Lundeheim, Professor, HGEN, SLU Ultuna

Rebecka Westin, VMD, HMH, SLU Skara


Pigs in their natural environment spend the majority of their time exploring their surroundings through rooting, sniffing and chewing to find food and resting places. Rooting under commercial conditions is often fully dependent on the provision of rooting material. Lack of rooting opportunity may redirect the exploratory behaviour and cause tail biting, an abnormal behaviour that causes acute, long- and short-term pain. Tail biting is a common issue in modern pig production, reducing health, profitability and animal welfare. To fulfil pigs’ explorative needs, the Council Directive 2008/120/EC states that pigs should have permanent access to a sufficient amount of material, such as straw, to enable proper investigation and manipulation activities.

However, instead of improving pig environment to reduce tail biting, >90% of pigs in the EU are tail docked despite the prohibition of routine docking. Docked pigs have a less attractive and more sensitive tail tip and are less willing to allow biting. Docking aims at reducing the symptoms of tail biting rather than eliminating the cause. One argument for not increasing exploration through e.g. straw provision is fear of poor hygiene.

The overall aim of this thesis was to investigate the effect of straw on tail lesions, behaviour and hygiene (Studies I and II) as well as investigating tail position as a method for early detection of tail biting (Study III) in commercial production. Study I showed that 99% of Swedish farmers provide their pigs with straw (mediangrowers: 29 gram/pig/day; medianfinishers: 50 gram/pig/day). The amount of tail biting recorded at the abattoir was on average 1.7%. Study II showed that an increased straw ration decreased presence of tail wounds and initiated more straw-directed behaviour. Straw had little effect on hygiene. Study III showed that tail posture (hanging or curled) at feeding correctly classified 78% of the pigs with tail wounds. Less severe tail damage, e.g. swelling or bite marks, did not affect the tail posture.

The main conclusions are that increased straw reduces tail damage as well as pen-directed behaviours. Instead, straw increases straw-directed behaviours, while not affecting pig and pen hygiene negatively. Hence, it should be possible to rear pigs with intact tails without the use of tail docking in the EU.

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Chains as enrichment for pigs (Book chapter with supplement)

Chains as proper enrichment for pigs (incl. supplement) (Book chapter in Advances in Pig Welfare, M Spinka (Editor), Elsevier).

Rearing pigs in barren conditions reduces their welfare. Enrichment of pig pens is needed to allow the performance of species-specific natural behaviour like rooting. A metal chain provides rather limited enrichment, but when presented in an optimized way, may substantially improve the welfare of conventionally reared pigs in a most feasible way. The short metal chain can be optimize into the branched chain design. This is a long anchor-chain type chain reaching til floor level, with 2 or 3 shorter chain branches at nose height, and 1 such a branched chain being provided for every 5 pigs in the pen.

The underlying ideas are described in this book chapter:

Bracke MBM. Chains as proper enrichment for pigs (incl. supplement). In: Spinka M, editor. Advances in Pig Welfare: Elsevier (2017). The chapter (without supplement) can also be downloaded here.


This chapter primarily compiles work in which the author (Marc Bracke) has been involved with providing science-based decision support on the question of what is proper enrichment material for intensively-farmed pigs as required by EC Directive 2001/93/EC. Proper manipulable material should primarily provide occupation (i.e. reduce boredom), and preferably reduce tail biting.

The RICHPIG model was built expressing enrichment value as a score on a scale from 0 to 10. Metal objects like short metal chains had the lowest score. Subsequently, the Dutch government banned the use of metal chains, and most Dutch pig farmers attached a hard plastic ball or pipe to the prevalent, short metal chain. Unfortunately, our on-farm observations repeatedly suggested that this ‘enrichment’ may have reduced pig welfare, rather than improving it as intended by the Directive.

So-called AMI (animal-material interaction) sensors can be used to (semi-)automatically record object manipulation by attaching a motion sensor to hanging objects. Exploratory data are presented to, directly and indirectly, record enrichment value. AMI-sensors may provide objective, flexible and feasible registration tools of enrichment value, but their application is still rather demanding.

That the enrichment value of short metal chains can be improved upon, e.g. by providing branched chains. Essentially, this entails making chains longer, preferably reaching until the floor, and making them more readily available in a pig pen. To facilitate the process towards proper enrichment the principle of intelligent natural design (IND) is proposed. IND entails organising a repeated selection process of the (currently) best-available enrichment material so as to gradually reduce pig boredom and enhance the opportunities for the rearing of pigs with intact tails. IND should start with basically all pig farmers implementing promising enrichment like the branched-chain design on their farms as soon as possible, followed by conducting small-scale on-farm experiments to compare and improve enrichment through sharing of available knowledge. Suggestions are given as to how and why this novel approach can be implemented to solve persistent animal-welfare problems like providing proper enrichment for intensively-farmed pigs.

Related posts:

Chains as enrichment for pigs (Book chapter with supplement)
Ketting als hokverrijking voor varkens (incl. link naar het supplement)
Pig animation – Improved, branched chain design as proper enrichment for pigs
Branched chains as enrichment for pigs (technical description, pictures and video)
Proper enrichment for intensively-farmed pigs – From review to preview
A collection of pictures of other enrichment materials for pigs can be found here: Prize contest (Prijsvraag) 2011.
Do pigs play with chains? Science versus society

The video below shows the value of a branched chain provided in the outdoor run of organic pigs. This prototype branched was called ‘enriched chain’ because it was having various branches and reaching till the floor. The prototype was not yet made of stainless steel anchor chain links, but of relatively large c-chain links (2.5 cm wide, 5.5 cm long). It also shows that pigs show signs of frustration when trying to manipulate the hockey-type ball hanging on a short chain.

AMI-sensors, Farewelldock and the future of pig farming

This is a brief note on the use of AMI-sensors and the future of pig farming from the NL partner (MB) in the FareWellDock project.

The future of pig farming

The world is rapidly changing it seems, in major respects. A major energy transition is taking place reducing the dependence on fossil fuels. Agriculture must become more circular to reduce its impact on global warming. Another major transition that is taking place is the increasing role of information technology. Smart farming may soon become reality.  At the same time farm-animal welfare is an increasingly-recognised societal concern.  Since I have been working as an scientist on the interface between information-technology and pig welfare for some time now, I thought it could be interesting to share some thoughts on what the future of pig farming might look like.

AMI sensors

My most recent work related to smart farming, at least to some extent, was on AMI sensors of pig enrichment. AMI stands for animal material interactions. AMI sensors can take various shapes and forms. In some way or other AMI sensors record the amount of interaction pigs have with enrichment materials for pigs. Mostly this concerns hanging toys like chains and ropes with or without suspended materials like pieces of wood. So far the use of AMI sensors is (mainly) restricted to applications for scientific purposes, e.g. to measure the value of (different aspects of) enrichment materials (directly or indirectly), the effect of tail-biting ointments, and abnormal and/or sickness behaviour. Using AMI sensors it was possible to acquire new knowledge about enrichment. For example it was confirmed more objectively that destructibility is important for pigs. And we found that repellents may have some effect in reducing tail biting, and that pigs in tail biting pens seem to be more eager to interact with enrichment than pigs in control pens. (You can find my publication list of AMI sensors and abstracts here.) However, AMI sensors are not ready to be implemented for on-farm use, as their application generates difficulties partly because pig pens constitute a rather challenging environment for electronics but also in relation to how to properly interpret what is being recorded.

Decision support system

In 1996 I started my PhD research. I examined ways in which information technology could be used to assess animal welfare. I developed a methodology, called semantic modelling of animal welfare to derive welfare scores based on scientific knowledge. I implemented these principles to assess the welfare state of pregnant sows by developing a decision support system to assess sow welfare (the SOWEL model). A lesson regarding the future of pig farming from my PhD research may be that farmers shouldn’t be expecting that information technology and smart farming is going to make their life a lot simpler. The implementation of smart farming won’t be comparable to farmers buying a sat nav device for their farms, allowing them to forget all about road maps.

AMI sensors are not like sat nav

Tail biting and FareWellDock

As the name suggests the FareWellDock project was an international research project aimed to reduce routine tail docking of pigs in the EU. EU legislation has banned tail docking for many years now and it is most likely that future pig farming will require raising pigs with intact tails without much tail biting. This is going to be a major challenge for conventional pig farming. Countries like Denmark, the UK, Germany and the Netherlands are in various stages on the road towards this goal. Some countries like Finland and Sweden may even be said to have arrived at their final destination in this respect. Even in these countries, however, there is a continuing need to reduce tail biting and improve pig enrichment, a major risk factor for tail biting.

From my work on tail biting two major suggestions regarding the future can be made. One recommendation extends the previous one, that farming isn’t going to be simple. Tail biting is a multifactorial problem, i.e. many stressors related to enrichment, climate, feed and social conditions, may contribute to it. Underlying most of these risk factors, however, are decisions made by the farmer him/herself. In line with this I have previously suggested that perhaps the pig farmer may well be the most important risk factor for tail biting. Farmers do not always appreciate this.

The other suggestion concerns the conventional view that scientists should first solve a problem before farmers should implement it. This may have worked well with problems in the past, but it may not work for the remaining, more persistent problems like improving enrichment and raising pigs with intact tails. It is more likely that pig farmers will have to take the initiative and perhaps even start to do some collaborative ‘research’ themselves (for more details on this idea, which I have labelled ‘intelligent natural design’ see Bracke, 2010, Bracke et al., 2011, Bracke, 2016 and esp. Bracke, In press (forthcoming in june 2017)).


Tail docking: The final cut?

Tail docking: The final cut? By Monique Pairis-Garcia. You can read the first part of this article here. For the second part see the original at the Pig Progress site (published August 8, 2016).

Tail docking is applied to young piglets to avoid a potential problem later of tail biting. However, should the root of the problem be looked at instead of using this preemptive measure?

Tail docking is routinely performed on farms as a means to decrease the prevalence of tail biting. Tail biting is an abnormal redirected exploratory behaviour that results in mild to severe injury of pen mate’s tails. Several factors have been associated with tail biting behaviour including environment, nutrition, gender, genetics and health status.

Tail docking of piglets has and continues to be highly criticised in both the US and Europe. This is primarily driven by the fact that tail docking is a painful procedure as indicated by changes to the physiology and behaviour of pigs who are tail docked.

Eliminate tail docking and control tail biting

Most recently, European countries have taken a stance to eliminate this management practice by managing the problems which lead to tail biting in the first place. Several research projects including FareWellDock have been established to provide scientific research to determine the best practices to eliminate tail docking and control tail biting. Although several factors can contribute to tail biting, research has consistently demonstrated that the absence of material for manipulation increases risk of tail biting. Several enrichment objects including chains, rubber hoses, car tires, straw and peat moss have shown to decrease tail biting but not necessarily eliminate the behaviour altogether.

Unlike the European approach, the US is nowhere near implementing the elimination of tail docking on farm. Tail docking is still performed routinely on commercial swine operations in the US. Farms which are not tail docking are either smaller farms which provide outdoor access to pigs or farms on specified animal welfare friendly programmes like Animal Welfare Approved, American Humane and Certified Humane.

For the second part of this article (on the probability of eliminating tail docking and the value of enrichment) see the original at the Pig Progress site (and see also the comment section).


What are the effects of tail docking on piglets?

What are the effects of tail docking on piglets? Interview with Dr Pierpaolo Di Giminiani by Vincent Ter Beek in Pig Progress (August 8, 2016). Here you find the first half of the interview. The whole article can be found on Pig Progress.

The practice of tail docking is applied to young piglets to avoid a potential later problem of tail biting. But are there effects of docking on piglets? Very few researchers have asked that question, found Dr Pierpaolo Di Giminiani, researcher at Newcastle University, UK.

Is a tail actually a sensitive part of the pig’s body? Dr Pierpaolo Di Giminiani thinks for a while and says, “That is a very good question! I would say it is not more or less sensitive than other parts of the body. The tail is full of neuro-anatomical structures responsible for the pain response. It is comparable to our human skin.” Unlike in many other animals, the pig’s tail may not have a wide range of functions. At best it serves to chase insects away and when in a curl, it gives an indication of the animal’s health. Still, when something happens to that tail, whether this be being docked or bitten, this body part responds like any other.


Dr Pierpaolo Di Giminiani is a research associate with a focus on ethology (animal behaviour) at Newcastle University, UK. During his graduate studies at Linköping University in Sweden, he studied the cognitive impairment caused by anaesthetic protocols in rodents. At his doctorate at Aarhus University, Denmark, he focused on the assessment of behavioural measures of pain in pigs as a result of cutaneous inflammation. Currently, he investigates pain in pigs in relation to the practice of tail docking in piglets and tail injuries in older pigs.

Tail docking – and especially the effects of tail docking on piglets – has been the focus of Di Giminiani’s studies since the beginning of 2014. They form part of the FareWellDock research programme, an international conglomerate funded by the European Union, zooming in on the common problem of tail biting, the preventive solution of tail docking, virtually common everywhere in Europe, and what can be done to overcome both. Especially tail docking of piglets is a practice which is increasingly frowned upon in some European countries. For more information on FareWellDock, see box below.

Di Giminiani’s studies have mainly centred on the question of whether piglets in the short and long term suffer from any pain from tail docking. In an interview with Pig Progress, Di Giminiani points to pain being a very complex experience and it being difficult to measure properly. He says, “I find it fascinating because there is a lot that we can do, especially in a species like the pig. A lot has been done in humans and laboratory animals and we now have the opportunity to apply novel techniques in other animal species. In addition, pain mitigation is often not provided or done so arbitrarily due to the lack of valid measures of pain in non-verbal animals. Therefore, it still remains one of the big open questions in research.”

Measuring pain in animals

In many other animal studies, Di Giminiani explains, research on pain sensitivity is fairly common. Before he set himself onto the theme of pain in piglets, an academic journey took him from his native Italy to San Diego, United States and later Linköping, Sweden, to learn and discover more on pain perception in laboratory rodents.

In pigs, however, everything was different, he says, as similar research appeared to be virtually absent in pigs when starting his PhD in Denmark at Aarhus University. Indeed, a bit strange, considering that pigs have an important role to play virtually all over the world – and considering the fact that from a medical perspective, pigs and humans are very similar.

The current research on pain sensitivity around tail docking in piglets at Newcastle University roughly revolves around three questions, Di Giminiani explains:

Is pain actually occurring or not and how long does it last?
What is the level of pain experience for piglets?
Based on the outcome, what can be done – for instance the use of painkillers?
Di Giminiani says, “Basically, there are 2 common methods to assess pain in animals:

To observe spontaneous behaviour. You just observe the activity of the animals, e.g. how much they walk – their locomotion – how much they lie, how much they stand, how do they drink, how do they eat, etcetera.
“Another method revolves around stimulus and reception – how do animals react to certain controlled challenges? We apply a controlled challenge to evoke a reaction.” This last method had not been applied in pigs a lot, but was used at Newcastle University to figure out short and long-term effects of tail docking on piglets.
Di Giminiani’s research team applied a gas-heated iron for tail docking, so that any wound would immediately be closed to avoid infections. He says, “In addition to measuring responses to controlled stimuli, we developed a grimace scale to measure the facial expressions of piglets. They do seem to grimace, particularly that they squint with their eyes in the minutes immediately following tail docking.” A full scientific paper related to the findings will be sent for publication in the summer of 2016.

For the last three sections of this interview (Pain in animals in the longer term; Does it matter?; FareWellDock) see the original article, as well as several related articles, on the Pig Progress site.

Tail docking using hot iron cautery

Amount of straw needed to satisfy manipulation needs of growing-finishing pigs

Bodin L, Algers B, Andersson M, Olsson AC, Botermans J. The amount of straw for growing- finishing pigs considering the reduction of time spent in manipulative behavior. Symbiosis J of Vet Sci. 2015, 1: 105.


The behavior of rooting and digging is highly motivated in the pig. The motivation to perform this exploratory behavior is not reduced even after the dietary requirement has been fulfilled through feeding. The aim of this study was to identify the minimal amounts of straw needed to satisfy pig motivation for manipulation and reduce to a minimum the manipulating behavior of pigs directed toward pen mates. To determine the minimal amount of straw needed for conventional growing-finishing pigs, a study using 168 pigs provided with 7 different amounts of straw (20, 40, 60, 80, 100, 200 or 300 grams/ pig/ day) was performed. The straw was provided either once or four times per day. Behavior observations were made using focal animal sampling and continuous recording for one hour between 9 and 10 am and between 3 and 4 pm.

The time spent by the pigs manipulating straw increased over 10% ranging up to 27% in all the pens receiving over 200g of straw per day compared to the range from 4-22% in pens receiving 20-100g of straw. Meanwhile, the time spent in redirected behavior decreased below 5% in all the pens receiving over 200g of straw per day. No significant differences were found when comparing pens provided with straw once or four times per day.

2nd Animal Welfare Day

SRUC organises the 2nd Animal Welfare Day.
2015 marks 50 years since the publication of the report of the Brambell Commission which really began the scientific investigation of animal welfare, and laid the foundations for the Five Freedoms.
SRUC marks this anniversary with talks, demonstrations and discussions around the theme of the Five Freedoms, incl. the hosting of a webinar.
The 2nd Animal Welfare Day is held on 8th October 2015 at the Roslin Institute Building, Easter Bush Campus.
FareWellDock partner Dale Sandercock will be using this event to discuss and demonstrate quantitative image analysis (histopathology and TEM) in relation to tail docking in pigs from the FareWellDock project.
Entry is free but requires registration (see flyer).

Invitation 2nd Animal Welfare Day SRUC


Media coverage


Coverage of the project startup:

FI: Telkanranta, H. (in prep. 2014). Uusi EU-tutkimushanke tähtää tulevaisuuteen ilman hännäntypistystä (New EU-project aims at a future without tail docking). KMVET

DK: New EU project to reduce tail biting, docking in pigst (Feedstuffs, the weekly newspaper for agribusiness (Dec 2013)

DK: New EU project to reduce tail biting, docking (Pig Progress, Dec 4, 2013)

NL: Waninge (In prep.) Prikkelvoer – Opvoeding biggen leidt tot minder staartbijten (Stimulation feed – Rearing of piglets reduces tail biting). Varkens (Interview with Prof. Valros).
Op weg naar coupeervrij Europa (Towards a docking-free Europe) (Varkens, Dec 5, 2013)

SE: Dr. Stefan Gunnarsson of SLU was interviewed about the FareWellDock project on Sveriges radio (17-7-13, in Swedish).

UK: See the post on the UK’s media coverage to the press release issued by SRUC.