Table 4 Refined acute pain scale in horses submitted to castration after the refinement of the data based on the specificity, relevance and criterion validity

Positioning in the stall

The horse’s head is at the outside door

0

The horse is inside the stall, but looking at the outside door, observing the environment

1

The horse is eating

0

The horse is not close to the outside stall door and does not look interested in the environment

2

Locomotion

The horse moves freely alone

0

The horse does not move, or is reluctant to move

1

The horse is agitated, restless

2

Locomotion when led by the evaluator

The horse moves freely when led

0

The horse does not move, or is reluctant to move when led

1

The horse is agitated, restless

2

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

Mild reaction to palpation of the surgical wound

1

Violent reaction to palpation of the surgical wound

2

Looking at the flank

The horse does not look at the flank

0

The horse looks at the flank

1

Kicking at the abdomen

The horse does not kick the abdomen

0

The horse kicks at the abdomen

1

Lifting hind limbs

No lifting of hind limbs

0

Lifting hind limbs

1

Lifting hind limbs and extending the head

2

Head movement

Head straight ahead most of the time

0

Lateral and/or vertical occasional head movements

1

Lateral and/or vertical continuous head movements

2

Pawing on the floor (fore limbs)

Quietly standing, no pawing

0

Pawing

1

Heart rate (compared to initial values)

25-50% increase

1

>50% increase

2