Table 1.
Variables, criteria, scores, content validity and reproducibility of the acute pain scale in horses
| Variable | Criteria | Score | Content validity 1 | Reproducibility 2 | ||||||
| EV1 X EV2 | EV1 X EV3 | EV1 X EV4 | EV2 X EV3 | EV2 X EV4 | EV3 X EV4 | |||||
| Posture | Positioning in the stall | The horse’s head is at the outside door | 0 | 0.7 | 0.6 (0.4-0.7) | 0.6 (0.4-0.8) | 0.6 (0.5-0.8) | 0.7 (0.5-0.8) | 0.5 (0.3-0.7) | 0.6 (0.4-0.7) |
| The horse is inside the stall, but looking at the outside door. Observing the environment | 1 | * | 0.5 (0.3-0.7) | 0.4 (0.2-0.6) | 0.5 (0.3-0.7) | 0.5 (0.3-0.7) | 0.3 (0.1-0.6) | 0.4 (0.2-0.6) | ||
| The horse is eating | 0 | * | 0.7 (0.4-1.0) | 0.7 (0.5-1.0) | 0.6 (0.3-0.9) | 0.8 (0.6-1.0) | 0.7 (0.4-1.0) | 0.7 (0.4-1.0) | ||
| The horse is not close to the outside stall door and does not look interested in the environment | 2 | 1 | 0.9 (0.6-1.0) | 0.6 (0.3-1.0) | 0.7 (0.4-1.0) | 0.7 (0.4-1.0) | 0.8 (0.6-1.0) | 0.8 (0.6-1.0) | ||
| Head position | Above the withers or grazing | 0 | 1 | 0.4 (0.1-0.7) | 0.4 (0.1-0. 7) | 0.5 (0.2-0.7) | 0.6 (0.3-1.0) | 0.6 (0.2-0.9) | 0.8 (0.6-1.0) | |
| At the level of the withers | 1 | * | 0.3 (0–0.7) | 0.3 (0–0.6) | 0.3 (0–0.6) | 0.5 (0.1-1.0) | 0.3 (−0.2-0.7) | 0.5 (−0.1-1.0) | ||
| Below the withers but not eating | 2 | 1 | NE | NE | NE | 1.0 (1.0-1.0) | 0.7 (0.04-1.0) | 0.7 (0.04-1.0) | ||
| Interactive behaviour | Response to opening the door | The horse moves towards the door or is already positioned at the outside door | 0 | 0.7 | 0.7 (0.6-0.9) | 0.7 (0.5-0.9) | 0.4 (0.2-0.6) | 0.7 (0.6-0.9) | 0.4 (0.2-0.6) | 0.5 (0.3-0.8) |
| The horse looks at the door, but does not move towards the door | 1 | 0.7 | 0.6 (0.4-0.8) | 0.5 (0.2-0.7) | 0.3 (0.1-0.6) | 0.6 (0.4-0.8) | 0.3 (0.1-0.6) | 0.5 (0.2-0.7) | ||
| The horse does not respond to opening the door | 2 | 0.7 | 0.4 (0–0.8) | 0 (0–0) | 0.5 (0.0-0.9) | 0.3 (−0.2-0.8) | 0.2 (−0.2-0.7) | 0 (0–0) | ||
| Response to approach and presence of the observer | Moves towards or looks to the observer | 0 | 0.7 | 0.2 (0.1-0.3) | 0.3 (0.1-0.4) | 0 (0–0.1) | 0.5 (0.3-0.7) | 0 (−0.1-0.2) | 0.1 (−0.1-0.3) | |
| Moves away from the observer | 1 | 0.7 | 0.1 (−0.2-0.4) | 0.2 (−0.2-0.6) | 0 (0–0) | 0 (0–0) | 0 (0–0) | 0 (0–0) | ||
| Does not move | 2 | 0.7 | 0.2 (0–0.3) | 0.2 (0–0.4) | 0.1 (0–0.1) | 0.5 (0.2-0.7) | 0.1 (−0.1-0.3) | 0.1 (0–0.4) | ||
| Appetite | Appetite for hay | The horse eats hay | 0 | 0.7 | 0.2 (−0.2-0.6) | 0.7 (0–1.0) | 0.7 (0–1.0) | 0.3 (−0.1-0.7) | 0.3 (−0.1-0.7) | 1.0 (1.0-1.0) |
| The horse does not eat hay | 1 | 0.7 | 0.3 (−0.2-0.7) | 0.7 (0–1.0) | 0.7 (0–1.0) | 0.3 (−0.1-0.8) | 0.3 (−0.1-0.8) | 1.0 (1.0-1.0) | ||
| Response to concentrate food | Moves to the food and eats | 0 | 0.7 | −0.2 (−0.3- -0.1) | 0.4 (0–0.7) | 0.3 (0–0.6) | 0.2 (0.1-0.5) | −0.1 (−0.2- -0.1) | 0.4 (0–0.7) | |
| Hesitates to move towards the food, but eats | 1 | 0.7 | −0.1 (−0.2- -0.1) | 0.6 (0.2-0.9) | 0.4 (0.1-0.8) | 0.2 (−0.1-0.5) | −0.1 (−0.2- -0.1) | 0.4 (0–0.7) | ||
| Shows no interest in food, not eating | 2 | 0.7 | NE | NE | NE | NE | NE | NE | ||
| Activity | Locomotion | The horse moves freely alone | 0 | 0.7 | 0.1 (0–0.2) | 0.5 (0.3-0.8) | 0.3 (0.1-0.6) | 0.1 (0–0.2) | 0.1 (0–0.2) | 0.3 (0.1-0.6) |
| The horse does not move, or is reluctant to move | 1 | 1 | 0.1 (0–0.3) | 0.5 (0.3-0.8) | 0.5 (0.2-0.8) | 0.1 (0–0.2) | 0.1 (0–0.3) | 0.5 (0.2-0.9) | ||
| The horse is agitated, restless | 2 | 1 | NE | NE | NE | NE | 0.1 (−0.2-0.5) | NE | ||
| Locomotion when led by the evaluator | The horse moves freely when led | 0 | 0.7 | 0 (−0.2-0.1) | 0.3 (0–0.7) | 0.7 (0.4-1.0) | 0.1 (0–0.3) | 0.1 (0–0.2) | 0.6 (0.3-1.0) | |
| The horse does not move, or is reluctant to move when led | 1 | 1 | 0.1 (0–0.2) | 0.5 (0.1-0.9) | 0.8 (0.5-1.0) | 0.1 (0–0.3) | 0.1 (0–0.2) | 0.6 (0.3-1.0) | ||
| The horse is agitated, restless | 2 | 1 | NE | NE | NE | NE | NE | NE | ||
| Variable | Criteria | Score | Content validity 1 | Reproducibility 2 | ||||||
| EV1 X EV2 | EV1 X EV3 | EV1 X EV4 | EV2 X EV3 | EV2 X EV4 | EV3 X EV4 | |||||
| Palpation | Response to palpation of the painful area (approximately 3 cm besides the wound) | No response or change in relation to pre-procedure palpation response of the surgical wound | 0 | 1 | 0.5 (0.3-0.6) | 0.7 (0.5-0.8) | 0.7 (0.5-0.8) | 0.7 (0.5-0.8) | 0.6 (0.5-0.3) | 0.7 (0.6-0.9) |
| Mild reaction to palpation of the surgical wound | 1 | 1 | 0.3 (0.1-0.5) | 0.5 (0.3-0.7) | 0.6 (0.5-0.8) | 0.4 (0.3-0.6) | 0.3 (0.1-0.5) | 0.4 (0.2-0.6) | ||
| Violent reaction to palpation of the surgical wound | 2 | 1 | 0.3 (0–0.6) | 0.4 (0.2-0.7) | 0.6 (0.3-0.9) | 0.6 (0.4-0.8) | 0.4 (0.1-0.7) | 0.5 (0.2-0.7) | ||
| Interactive behaviour | Response to an auditory stimulus (clap hands) | Moves and/or pays attention with ears or head movements | 0 | * | 0.3 (0.1-0.5) | 0.4 (0.1-0.6) | 0.3 (0–0.5) | 0.4 (0.1-0.6) | 0.5 (0.2-0.7) | 0.6 (0.4-0.8) |
| Calm, no response | 1 | * | 0.4 (0.2-0.7) | 0.5 (0.-3-0.8) | 0.4 (0.1-0.6) | 0.4 (0.1-0.6) | 0.5 (0.2-0.7) | 0.6 (0.4-0.8) | ||
| No response to auditory stimulus due to prostration | 2 | * | NE | NE | NE | NE | NE | NE | ||
| Miscellaneous behaviours | Looking at the flank | The horse does not look at the flank | 0 | 0.7 | 0.4 (0.2-0.7) | 0.3 (0.1-0.5) | 0.4 (0.2-0.7) | 0.5 (0.3-0.7) | 0.5 (0.3-0.7) | 0.6 (0.4-0.7) |
| The horse looks at the flank | 1 | 0.7 | 0.4 (0.2-0.7) | 0.3 (0.1-0.5) | 0.4 (0.2-0.7) | 0.5 (0.3-0.7) | 0.5 (0.3-0.7) | 0.6 (0.4-0.8) | ||
| Kicking at the abdomen | The horse does not kick the abdomen | 0 | 0.7 | 0 (0–0) | 0.1 (−0.1-0.4) | 0.3 (0–0.7) | 0 (−0.1-0) | 0 (0–0) | 0.3 (0–0.6) | |
| The horse kicks at the abdomen | 1 | 0.7 | NE | 0.2 (0–0.5) | 0.5 (0–0.9) | NE | NE | 0.3 (0–0.6) | ||
| Lifting hind limbs | No lifting of hind limbs | 0 | * | 0.5 (0.3-0.7) | 0.5 (0.4-0.7) | 0.6 (0.4-0.8) | 0.4 (0.2-0.6) | 0.5 (0.3-0.7) | 0.6 (0.4-0.8) | |
| Lifting hind limbs | 1 | * | 0.3 (0.1-0.5) | 0.4 (0.2-0.5) | 0.5 (0.3-0.7) | 0.2 (0–0.4) | 0.3 (0.1-0.5) | 0.6 (0.4-0.8) | ||
| Lifting hind limbs and extending the head | 2 | * | 0.2 (0–0.5) | 0 (0–0) | 0 (0–0) | 0 (0–0) | 0.1 (−0.1-0.3) | 0 (0–0) | ||
| Head movement | Head straight ahead most of the time | 0 | * | 0.1 (0–0.2) | 0.1 (−0.2-0.4) | 0.6 (0.3-0.9) | 0 (−0.1-0.2) | 0.2 (0–0.4) | 0.4 (0–0.7) | |
| Lateral and/or vertical occasional head movements | 1 | * | 0 (−0.1-0.1) | 0 (−0.1-0) | 0.5 (0.2-0.8) | 0 (−0.1-0.2) | 0.1 (0–0.3) | 0.3 (0–0.7) | ||
| Lateral and/or vertical continuous head movements | 2 | * | 0 (0–0) | NE | NE | NE | NE | NE | ||
| Pawing on the floor (fore limbs) | Quietly standing, no pawing | 0 | 0.7 | 0.2 (0–0.5) | 0.2 (0–0.4) | 0.2 (0–0.5) | 0.3 (0–0.5) | 0.5 (0.2-0.7) | 0.7 (0.5-0.9) | |
| Pawing | 1 | 1 | 0.3 (0–0.6) | 0.2 (0–0.4) | 0.2 (0–0.5) | 0.4 (0.1-0.7) | 0.5 (0.2-0.7) | 0.7 (0.5-0.9) | ||
| Others | Moving the tail sharply and repeatedly | 1 | * | 0.1 (−0.1-0.2) | 0.3 (0.1-0.4) | 0.1 (−0.1-0.4) | 0.2 (0–0.4) | 0.2 (0–0.4) | 0.4 (0.3-0.6) | |
| Moving the tail sharply and repeatedly and lifting the hind limbs | 2 | * | 0.4 (0.1-0.7) | 0.4 (0.2-0.6) | 0.4 (0.1-0.7) | 0.3 (0.1-0.5) | 0.5 (0.2-0.8) | 0.5 (0.3-0.7) | ||
| Partial penis protrusion | 1 | * | 0.4 (0.1-0.5) | 0 (−0.2-0.2) | 0.1 (−0.1-0.4) | 0.2 (0–0.5) | 0.1 (−0.1-0.3) | 0.3 (0–0.5) | ||
| Penis protrusion | 0 | * | 0.4 (0.2-0.6) | 0.2 (0–0.4) | 0.5 (0.2-0.7) | 0.4 (0.1-0.7) | 0.5 (0.3-0.8) | 0.7 (0.5-0.9) | ||
1Content validity obtained by the arithmetic mean of the scores given by the three evaluators for each item of the scale [20].
2Inter-observer reproducibility was tested with the Kappa coefficient comparing video analysis among observers. > 0.7 - Excellent, 0.4 to 0.7 - moderate; <0.4 - poor reliability [21].
EV – Evaluator. NE – not evaluated as there were not sufficient data for statistical analysis (the behaviour was either very infrequent or not observed). * Item included after content validation.