ASKHQ: HORSE GRIMACE SCALE

Q: What is the Horse Grimace Scale?

A: The Horse Grimace Scale is a pain assessment tool that identifies six facial expressions of a horse and scores them on a scale of 0 (not present), 1 (moderately present) and 2 (obviously present). The actions are:

• Stiffly backwards ears– the horse’s ears are held stiffly and turned backwards, causing the space between the ears to appear wider at the top than the bottom.
• Orbital tightening – the horse’s eyelid is partially or entirely closed. Any closure that reduces eye size by more than half is coded 2 (obviously present).
• Tension above the eye area – contractions 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 clearly visible when the upper lip is drawn back, and the chin appears more pronounced.
• Strained nostrils and flattening of the muzzle’s profile – the horse’s nostrils look strained and slightly dilated, and the profile of the nose flattens with elongated lips.

The overall score gives an indication of the degree of pain a horse is experiencing.