Background and aim Tail docking has been suggested as an animal model of neuropathy and pain based on findings of relations between the degree of neuroma formation and the docking length. We examined effects of docking length on behaviour of piglets during and 6 h after tail docking. Methods Piglets were tail docked 2–4 d post-partum. We used 53 piglets and four treatments: intact (I), removal of either 25 (Q), 50 (H) or 75% (T) of the tail. The piglets were kept with sow and littermates under production conditions, and docked using a gas-heated instrument. Behaviour was observed during docking and for the following 6 h. Results Tail docking led to behavioural changes, the magnitude of which to some extend depended on docking length. Increased docking length led to increased intra-procedural vocalization score (0, 0.6 ± 0.2, 1.4 ± 0.2 and 1.4 ± 0.2 for I, Q, H and T, respectively, P <0.001). In the initial 6h, increased docking length led to increased time spent in the heated creep area (2 ± 1%, 15 ± 6%, 18±8% and 30±6% for I, Q, H and T, respectively; P <0.05). Piglet posture was affected as well, showing that increased docking length led to decreased lying (71 ± 2%, 68 ± 2%, 61 ± 2% and 61 ± 2% for I, Q, H and T, respectively, P <0.01) and increased time spent active (24 ± 2%, 23 ± 2%, 32 ± 2% and 30 ± 3% for I, Q, H and T, respectively, P < 0.05). Pain specific behaviours such as trembling or tail flicking were registered and occurred in 5 ± 1% and 9 ± 1% of observations. However, no effects of docking length could be shown. Conclusions Piglets responded behaviourally to tail docking. Increasing docking length led to increased pain responses such as intra-procedural vocalizations, hiding behaviour and reduced rest, indicative of increased pain. These results confirm earlier reports suggesting that tail docking might be suitable as an animal model for neuropathy and pain.