“Non-specific” behaviors
Suckling    Teat in the mouth. Vigorous rhythmic suckling movements.
Udder massage Nose in contact with the udder, leaning against it. Ample and rhythmic up and down head movements.
Teat seeking Attempts to find a teat by walking and pushing other piglets, while most of the others are suckling.
Nosing The snout is close to or in contact with a substrate or a pen-mate. Snout movements may be observed.
Chewing Nibbling at littermates (ears, tail or foot, etc.) or substrates.
Licking Rubbing the tongue over littermates, floor or pen walls.
Playing Head shaking, springing (sudden jumping or leaping), running with vertical and horizontal bouncy movements. Can involve partners (gentle nudging or pushing, mounting, chasing…).
Aggression Forceful fighting, pushing with the head or biting littermates in a violent manner.
Walking Slowly moving forward with one leg at a time.
Running Trot or gallop without sudden change in direction or speed.
Sleeping Lying down, eyes closed.
Pain-castration related behaviours
Huddled up Lying with at least 3 legs tucked under the body.
Trembling Shivering as with cold. The animal may be lying, sitting or standing.
Spasms Quick and involuntary contractions of the muscles under the skin, of a leg.
Scratching Scratching the rump by rubbing it against the floor or the pen walls.
Tail wagging Tail’s movements from side to side or up and down.
Lateral lying Motionless; body weight supported by side. Shoulder in contact with floor.
Ventral lying Motionless; body weight supported by belly. Sternum in contact with floor.
Sitting Motionless; body weight supported by hind-quarters and front legs.
Standing Motionless; body weight supported by the 4 legs.
Kneeling Motionless; body weight supported by front carpal joints and hind legs.
Social cohesion
Isolated Apart from other piglets, alone or with one pen-mate at the most. A distance of at least 40 cm (about the width of two piglets) separates the animal from the closest group of littermates.
Table 1: Description of behavioral categories.