Maria Calatayud-Bonilla PT, PhD, MSc Equine PT – Instructor
– Comparing horses and humans
– Challenges in assessment and pain expression
Introduction
How can we detect pain when it cannot be verbalized? This Clinical Pearl addresses the fascinating and unique clinical challenge of identifying myofascial pain in horses, integrating human knowledge with sensitivity to equine body language.
Equine myofascial pain presents unique challenges in its assessment, not only due to anatomical differences but, most importantly, behavioral differences compared to humans. While in humans, myofascial pain can be localized and verbalized, in horses, logically, it is not expressed directly. Their prey nature, which leads them to hide signs of pain to avoid being detected as vulnerable by predators, makes pain detection even more difficult (Ashley, 2005).
In fact, this is the first characteristic that makes it truly unique: its difficulty in detection. Although we may think this happens with any type of pain in an animal, which is true, equine myofascial pain has additional particularities that make it even more complex: it is not detectable through imaging, does not reflect in physiological parameters, and furthermore, it is comorbid with multiple conditions. We know this thanks to clinical and scientific work in human patients, where research has advanced significantly in recent decades. In equine medicine, on the other hand, we are still in an incipient phase.
We rely on the knowledge generated in humans to understand what might be happening in our horses. This requires clinical interpretation to be a transversal and comparative effort: integrating knowledge from neurophysiology, biomechanics, animal behavior, and clinical experience. And that, to me, makes it a fascinating field. Working with my human patients not only enriches me as a person but also provides a decisive advantage when helping my horses.
A horse is not just any patient: it is an athlete. And as such, its biomechanics are altered by any muscular dysfunction, no matter how minimal. Often, a performance issue, a change in attitude during training, or resistance to specific exercises may stem from active trigger points or referred pain patterns. The clinical history will rarely be clear. Sometimes the rider only notices “something strange” or says the horse “isn’t the same as before,” but they cannot pinpoint the problem itself. And sometimes, there may also be much more expressive gestures, even dangerous ones for the rider. Without knowledge of myofascial pain, we leave the diagnosis exposed.
Clinical Insight
Assessing pain in horses requires careful observation of changes in behavior, posture, and movement quality (Denoix, 2003; Gleerup, 2018). Validated scales analyzing equine facial expressions can benefit less experienced clinicians (Dalla Costa et al., 2014; Gleerup et al., 2016). However, just like with humans, practical experience and manual skills remain crucial (Barbero et al., 2018; Calatayud-Bonilla et al., 2018).
One of the most important clinical keys is learning to differentiate between pain and misbehavior. This remains one of the great challenges in fieldwork. Often, the rider interprets refusal as disobedience when in reality, it may be a protective response to pain (Dyson, 2017). The good news is that when the myofascial origin of the pain is treated, the response is usually immediate: the horse moves fluidly again and “stops fighting.” These cases are highly revealing for the rider, and that’s where, as clinicians, educating owners and trainers becomes fundamental.
Takeaway
Understanding the differences and similarities between human and equine myofascial pain is crucial to advancing its diagnosis and treatment. We cannot expect the horse to tell us where it hurts, but we can learn to listen to its body. We need more research, but above all, we need more clinicians trained in this transversal approach, capable of translating human experience into equine language. Only then can we offer our horses the same care and precision we provide our human patients. And it is this transversal approach that truly makes it unique.
References
Ashley, F. H., Waterman-Pearson, A. E., & Whay, H. R. (2005). Behavioural assessment of pain in horses and donkeys: Application to clinical practice and future studies. Equine Veterinary Journal, 37(6), 565-575.
Barbero, M., Bertoli, P., Cescon, C., Macmillan, F., Coutts, F., & Gatti, R. (2012). Intra-rater reliability of an experienced physiotherapist in locating myofascial trigger points in the upper trapezius muscle. Journal of Manual & Manipulative Therapy, 20(4), 171-177.
Calatayud-Bonilla, M., Resano-Zuazu, M., Segura-Orti, E. (2018). Intrarater reliability in locating myofascial trigger points in the equine brachiocephalicus muscle. Poster presented at: 28th Physiotherapy Symposium EUF ONCE. Fascia Scientific Advances. Madrid, Spain.
Dalla Costa, E., Minero, M., Lebelt, D., Stucke, D., Canali, E., & Leach, M. C. (2014). Development of the Horse Grimace Scale (HGS) as a pain assessment tool in horses undergoing routine castration. PLOS ONE, 9(3), e92281.
Denoix, J. M., & Dyson, S. J. (2003). The thoracolumbar spine. In M. W. Ross & S. J. Dyson (Eds.), Diagnosis and Management of Lameness in the Horse (pp. 509-521). W.B. Saunders, Philadelphia.
Dyson, S., Berger, J. M., Ellis, A. D., & Mullard, J. (2017). Can the presence of musculoskeletal pain be determined from the facial expressions of ridden horses (FEReq)? Journal of Veterinary Behavior, 19, 78-89.
Gleerup, K. B., & Lindegaard, C. (2016). Recognition and quantification of pain in horses: A tutorial review. Equine Veterinary Education, 28(1), 47-57.
Gleerup, K. B., Andersen, P. H., & Wathan, J. (2018). What information might be in the facial expressions of ridden horses? Adaptation of behavioral research methodologies in a new field. Journal of Veterinary Behavior, 23, 101-103.
