b'IS YOUR HORSE HURTING?A low level of basal (the minimal level that achieves a physiologic effect) oxytocin could be a marker of better well-being, in a social context, she says. For instance, higher basal levels of oxytocin in plasma were observed in prairie voles subjected to chronic social isolation, in lambs reared without a mother, and in humans with greater relational distress. It is also known that oxytocin affects levels of anxiety and stress, and during periods of distress oxytocin levels increase. This could also be the case in horses, but further research is required to confirm this result and understand the underlying mechanisms.Future studies on eye blink rate might also yield more information, because blink rate is associated with levels of dopamine, a neurotransmitter that tends to elevate with pain.Testing for PainOwners and veterinarians can test horses for pain using a variety of meth-ods. One is gauging a horses response to analgesics (painkillers) such as non-steroidal anti-inflammatory (NSAID) or opioid-type medications. They can also palpate or manipulate limb structures to see if the horse withdraws from the touch due to discomfort. A device called a pressure algometer allows them to detect areas of back pain by amplifying pressure DR. NANCY LOVINGover a suspected injury until the horse reacts.However, all these methods are time-consuming and dont always correlate This horse is demonstrating obvious pain and discomfort through his grimace expression: laid-back with pain, because a variety of otherears, pursed lips and taut mouth, taut nostrils, and a checked-out eye expression, looking inward stimuli might elicit similar behavioralrather than being engaged with his surroundings.changes or elevated heart rates.when assessing pain, not only in otherwhich is complex due to the poten-Horse Grimace Scale humans but also in animal species, Dallatially greater number of behaviors that Researchers are now using a differentCosta says. A relatively short trainingneed to be scored, says Dalla Costa. set of markers to assess equine pain andsession using a manual with pictures andBehavior-based assessments are more discomfort. A horses ears and eyes aredetailed descriptions of facial action unitstime- consuming to conductthe horse extremely expressive, as are his highly(FAUs) helps horse owners learn and ap- needs to be observed for a longer time, mobile lips and nostrils. Researchers haveply grimace scales to achieve reliable painparticularly in conditions inducing only identified a number of facial expressionsevaluation of their animals.mild pain. Furthermore, some behavioral that correlate well with a horses painShe adds that while the grimace scalepain assessments that include palpation level based on a system called the horseis seemingly easy to apply, some FAUs areof the painful area can be dangerous for grimace scale (HGS). Emanuela Dallamore difficult to assess than others, soboth veterinarian and horse. Costa, DVM, PhD, Dipl. ECAWM, and col- owners and veterinarians should undergoIn contrast, changes in equine facial leagues from the Universita degli Studi ditraining before using the scale to evaluateexpressions are detectable without hav-Milano Department of Veterinary Medi- a horse. ing to approach the subject, she says. cine, in Milan, Italy, developed the HGS.The use of the horse grimace scaleGrimace assessment is used quite easily This method exploits the natural hu- for scoring pain has distinct advantagesduring routine daily work around the man instinct of focusing on head and faceover that of manual behavior analysis,horses.14December 2019The Horse|TheHorse.comDetectingPain.indd 14 10/31/19 1:48 PM'