Monthly Archives: September 2019

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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