A: The Horse Grimace Scale is a pain assessment tool that identifies six facial expressions of a horse or pony and scores them on a scale of 0 (not present), 1 (moderately present) and 2 (obviously present). The actions that are scored are:
- Stiffly backwards ears – the horse or pony’s ears are held stiffly and turned backwards, causing the space between the ears to appear bigger at the top than the bottom.
- Orbital tightening – the horse or pony’s eyelid is partially or entirely closed. Any closure that reduces eye size by more than half is scored 2 (obviously present).
- Tension above the eye area – tightening of the muscles in the area above the eye causes the underlying bone to appear more prominent.
- Prominent strained chewing muscles – this is due to increased tension above the mouth.
- Mouth strained and pronounced chin – a strained mouth is present when the upper lip is drawn back, and the chin appears more obvious.
- Strained nostrils and flattening of the muzzle’s profile – the horse or pony’s nostrils look strained and slightly enlarged, and the profile of the nose flattens with longer lips.
