Effects of two methods of tooth resection on tooth integrity and piglet behaviour immediately before and after treatment

Erupted front deciduous teeth are often resected in pig farms to limit lesions that intact teeth may inflict to other piglets or the sow’s udder. Two techniques are commonly used: clipping with pliers and grinding with a rotating grindstone. Both techniques are potential sources of pain and stress. We analysed piglet behaviour just before and after tooth resection to identify changes that could indicate pain or distress. Behavioural observations focussed on oral behaviours, locomotion, ear position and movements, and vocalisations. In total, 120 piglets from 20 litters were allocated to clipping with sterilised pliers (CLIP), grinding with a hand-held rotative grindstone (GRIND) or SHAM-grinding at 1–4 days after birth (40 piglets/treatment, 2 piglets/treatment/litter). SHAM piglets were handled and treated as those in the GRIND group with a protective covering on the grinder head to prevent tissue damage. For resected piglets, the tip of the canines and third incisors was removed. Each litter was separated from the dam and placed in a heated holding trolley. Selected piglets were taken individually to a separate room and placed in an observation box for 1 min to be video recorded. Thereafter, tooth treatment was applied by a trained handler, and resected teeth were measured and checked for the presence of blood. The piglet was returned to the observation box and video recorded again for 1 min. Once all selected piglets had been treated, the litter was returned to the dam. Mean treatment duration was 53, 48 and 46 s in the SHAM, GRIND and CLIP groups, respectively. Presence of blood on teeth after resection was significantly more frequent (P < 0.001) in CLIP (97.5%) than GRIND (22.5%) treated piglets. Only one behaviour, ‘champing’ (opening and closing an empty mouth) differed (P = 0.005) between treatments: occurring in 45% of SHAM and 80% of CLIP pigs (P < 0.05) with GRIND pigs being intermediate (60%). This behaviour was never observed pre-treatment. A marked influence of handling on piglet behaviour regardless of the treatment was evident: walking, exploring walls and ears back decreased, while immobility, not exploring, ears in front position, and head flicks increased significantly (P < 0.05) between the pre- and post-treatment periods, but were not affected by treatment. In conclusion, although handling stress masked some of the behavioural effects of acute pain, tooth clipping appears to be more detrimental than grinding, as it led to more frequent presence of blood and champing behaviour.