b'IS YOUR HORSE HURTING?Dalla Costa says most observers easilyHorse Grimace Scale Facial Action Unitsrecognize FAUs of expression such as:Asymmetrical and lowered ears, or earsFACIAL ACTION UNIT DESCRIPTIONheld stiffly backward;Contraction and tension of muscles above the eye area, with orbitalThe ears are held stiffly and turned Stiffly backward ears backward; movements are limited also in tightening; presence of environmental stimuliWithdrawn and unfocused stare; Strained or flared nostrils; The eyelid is half-closed or closed, the orbit Muzzle tension and/or pursed lips withOrbital tightening is contracted, eyes are not focused on the pronounced (crescent-shaped) chin; andenvironmentTension of the facial and chewing muscles. Increased muscle tension in the area above Lansade evaluated these markers in aTension above the eye area the eyes, the underlying bone structure study during which handlers groomedbecomes clearly visiblehorses in a standard manner, continu-ing even when horses reacted negativelyIncreased tension of the chewing muscles, to certain actions. She compared thisProminent strained chewingthat becomes prominent and clearly musclesto gentle grooming, in which the han- recognizabledler stopped if the horse demonstrated discomfort and continued if the horseStrained mouth, the corner of the lips is DR. EMANUELA DALLA COSTA ET AL., 2016clearly showed enjoyment.Mouth strained and shortened, the lower lip is tense, the chin Horses that feel uncomfortable duringpronounced chin is contract and becomes more pronounced grooming were more frequently observed(crescent-shaped)with their neck in a high position, eyes wide open or showing the whites, tight- Strained nostrils and flattening The nostrils are dilated and strained, the ened lips with the corner of the mouthof the profile profile changes, and you can see two raised jerkily, and asymmetrical ears, shebulges (one at the nostrils and upper lip)says. In contrast, a happy horse is relaxed in the neck, the eyes are half-closed, theridden-horse ethogram (descriptive listleast 10 seconds;upper lip is often extended, immobile, orof behaviors) is potentially more sensi- Head behind the vertical (>10) for at twitching, and the ears point backwardtive than the facial expression ethogramleast 10 seconds;together.that we developed specifically for riddenHead position changes regularly, tossed Pain and discomfort during groominghorses. However, we have shown that weor twisted from side to side, corrected induce distinct emotional states, whichcan differentiate many lame and nonlameconstantly;are expressed through different facialhorses by changes in facial expression.Ears rotated back behind vertical or expressions, Lansade says. HorsesThe ridden-horse ethogram cataloguesflat (both or one only) for at least five benefit from complex face muscles thatfacial expressions involving the ears,seconds or they repeatedly lie flat;allow expression of a wide range of facialeyes, nose, muzzle, mouth, and headEyelids closed or half-closed for two to movements, depending on the emotionalposition while ridden. It further includesfive secondsstate felt. body markers of head posture, tail posi-Sclera (white of the eye) exposed;tion, and head and tail movement. Gait Intense stare for five seconds;Ridden Horse Pain Ethogram markers include speed and regularity of Mouth opening or shutting repeatedly At the Animal Health Trusts Centerrhythm, responsiveness, bucking, rearing,with separation of teeth, for at least 10 for Equine Studies, in Newmarket, U.K.,and sudden stops. seconds;former head of Clinical OrthopaedicsThe following 24 behavioral markers Tongue exposed, protruding or hanging Sue Dyson, MA, Vet MB, PhD, DEO,are ones Dyson identified in her studiesout, and/or moving in and out;Dipl. ECVSMR, FRCVS, and her teamas occurring more commonly in lame Bit pulled through the mouth on one developed a list of observable behaviorsthan nonlame horses. She says horses dis- side;for horses under saddle, taking the horseplaying eight or more of these behaviors Tail clamped tightly or held to one side;grimace scale a step further to includewithin a five-minute period of workingLarge tail-swishing movements facial, body, and gait behaviors andon the bit are likely experiencing somerepeatedly up and down, side to side, expressions.level of musculoskeletal pain: circular, and/or during transitions;Not all horses experiencing muscu- Repeated raising or lowering of headA rushed gait (frequency of trot steps loskeletal pain show changes in facialposition; greater than 40/15 seconds), irregular expression, says Dyson. Different Head tilted or tilting repeatedly; trot or canter rhythm, or repeated horses react to pain differently, so theHead in front of vertical (>30) for atchanges of speed in trot or canter;TheHorse.com|The HorseDecember 201915DetectingPain.indd 15 10/31/19 1:48 PM'