Table 1.
Ethogram of piglet’s behavior during euthanasia for Experiments 1 and 2. Behavioral recordings started from the time the two straps of the box were latched. Interruptions shorter than 3 s are considered the same bout of behavior.
| Category | Behavior | Description |
|---|---|---|
| Duration | Stand | Up on four legs. |
| Lateral Lying | Lying down with side in contact with the floor. | |
| Ventral Lying | Lying down with sternum and belly in contact with the floor. | |
| Sit | One or two hind legs folded underneath the body and supporting weight on two front legs. “Sitting like a dog“. | |
| Kneel | One or two front legs folded underneath the body with hind legs straight. | |
| Locomotion | Any movement more than two steps; walk or run. | |
| Inactive | Immobile, not doing any particular behavior. | |
| Latency | Ataxic | Lack of muscle coordination in basic movements, loss of balance on one or more feet. |
| Loss of Posture 2 | Piglet lies on the ground and does not get back up. | |
| Heavy Breathing 2 | Forceful and quick repetition of flank movements, mouth closed. | |
| Open-Mouth Breathing 2 | Mouth open to breath from. | |
| Gaping 2 | Deep forceful, rhythmic movements of the chest with mouth open, a rudimentary brain stem reflex, deep state of unconsciousness. | |
| Last Movement 2 | Piglet stops gaping and does not move at all, is clinically dead. End of experiment time. | |
| Paddle Bout 1,2 | While lying laterally the piglet’s legs paddle/run. | |
| Events | Rooting Bout 1 | Snout in contact with the floor touching, sniffing, rubbing, or chewing. |
| Escape Attempt 1,2 | Rear on hind legs, jump (all limbs lose contact with the floor), or scratch with front legs against walls. | |
| Neck Stretch 1 | Extend neck as much as possible, head up. | |
| Foot Slips 1 | Piglet scrambles/loses balance while standing. | |
| Righting Response 1,2 | Unsuccessful effort to right up onto four legs. | |
| Squeal 1,2 | High-pitched vocalization; extended sound of high amplitude and frequency. | |
| Grunt 1 | Low-pitched vocalization; sound of low to medium amplitude. | |
| Intermediate 1 | Vocalization that starts out low-pitched and ends high-pitched. Neither a grunt or squeal but some combination. |
1 Behaviors recorded as events due to their brief nature, rather than as states; 2 Behaviors recorded for Experiment 2.