Tail posture predicts tail biting outbreaks in pigs

Tail posture predicts tail biting outbreaks at pen level in weaner pigs. By Helle Pelant Lahrmann, Christian Fink Hansen, Rick D’Eath, Marie Erika Busch, Björn Forkman, 2018. Applied Animal Behaviour Science 200: 29-35.


• Changes in tail posture can predict a tail biting outbreak at pen level.

• Percentage of hanging tails in pens close to an outbreak was almost doubled.

• A correlation between number of tail damages and lowered tails were identified.

• No changes in activity was identified prior to a tail biting outbreak.


Detecting a tail biting outbreak early is essential to reduce the risk of pigs getting severe tail damage. A few previous studies suggest that tail posture and behavioural differences can predict an upcoming outbreak. The aim of the present study was therefore to investigate if differences in tail posture and behaviour could be detected at pen level between upcoming tail biting pens (T-pens) and control pens (C-pens). The study included 2301 undocked weaner pigs in 74 pens (mean 31.1 pigs/pen; SD 1.5). Tails were scored three times weekly (wound freshness, wound severity and tail length) between 07:00 h–14:00 h from weaning until a tail biting outbreak. An outbreak (day 0) occurred when at least four pigs had a tail damage, regardless of wound freshness. On average 7.6 (SD 4.3) pigs had a damaged tail (scratches + wound) in T-pens on day 0. Tail posture and behaviour (activity, eating, explorative, pen mate and tail directed behaviour) were recorded in T-pens and in matched C-pens using scan sampling every half hour between 0800–1100 h 1700–2000 h on day -3, -2 and -1 prior to the tail biting outbreak in T-pens. Further, to investigate if changes in tail posture could be a measure for use under commercial conditions, tail posture was recorded by direct observation from outside the pen. The live observations were carried out just before tail scoring on each observation day until the outbreak. The video results showed more hanging/tucked tails in T-pens than in C-pens on each recording day (P < 0.001). In T-pens more tails were hanging on day -1 (33.2%) than on day -2 (24.8%) and day -3 (23.1%). Further, the number of tail damaged pigs on day 0 was correlated with tail posture on day -1, with more tails hanging in pens with 6–8 and >8 tail damaged pigs than in pens with 4–5 tail damaged pigs (P < 0.001). Live observations of tail posture in T-pens also showed a higher prevalence of hanging tails on day 0 (30.0%; P < 0.05) than on day -3/-2 (17.2%), -5/-4 (15.4%) and -7/-6 (13.0%). No differences in any of the recorded behaviours were observed between T-pens and C-pens. In conclusion, lowered tails seem to be a promising and practical measure to detect damaging tail biting behaviour on pen level even when using live observations. However, there were no changes in activity, eating, exploration or tail-directed behaviours prior to a tail biting outbreak.