Review argues trigger points may be a primary cause of equine lameness: full analysis

A new review in Frontiers in Veterinary Science is challenging a core assumption in equine lameness workups: that the primary pain source is usually articular, tendinous, or otherwise structural in the limb. Instead, the authors argue that myofascial trigger points, or MTrPs, can be a primary driver of lameness, performance decline, and pain behavior in horses, and that they’re often missed because standard diagnostic algorithms are still centered on gait observation, regional anesthesia, and imaging. (frontiersin.org)

That argument lands in a field where “whole horse” examination is already encouraged, but where muscle-based pain may still be underweighted in practice. Traditional lameness exams emphasize localization through palpation, flexion tests, gait assessment, diagnostic analgesia, and imaging, particularly when clinicians suspect distal limb disease. At the same time, equine practice literature has long noted that pain can present at a distance from the primary lesion, and that major muscle groups should be palpated during a full workup. The new review pushes that idea further by proposing that, in some cases, myofascial dysfunction is not merely compensatory, but causal. (msdvetmanual.com)

Scheibenpflug and Haussler synthesize evidence from equine and comparative medicine around several mechanisms. They describe the classic “energy crisis” model of trigger point formation, peripheral and central sensitization, and referred pain patterns that may make proximal muscle lesions look like distal limb pathology. The review specifically highlights muscles such as the gluteus medius, longissimus lumborum, and biceps femoris as potential sources of referred pain that could be clinically indistinguishable from joint or tendon disease. It also recommends systematic myofascial palpation as a first-tier addition to routine lameness diagnostics, with rapid improvement after targeted treatment treated as supportive evidence of a myofascial origin. (frontiersin.org)

The paper builds on a small but growing evidence base. Earlier observational work found spontaneous electrical activity in equine trigger points similar to findings in humans and other species, supporting biologic plausibility. More recent equine studies have reported that MTrPs are detectable in actively competing sport horses, with one 2025 study finding higher temperatures and stronger pain-related facial expression scores at trigger point sites than at control points in dressage and show-jumping horses. Another 2025 prospective study on dry needling described growing veterinary interest in trigger point physiology, while also noting that there are still no universally accepted diagnostic standards for equine trigger points. (journals.sagepub.com)

Industry and expert commentary appears to be moving in the same direction, even if not all of it is formal peer-reviewed reaction to this specific review. Kevin Haussler, the paper’s co-author and a longstanding figure in equine sports medicine and rehabilitation, has recently emphasized systematic head-to-tail palpation, muscle tone assessment, and recognition of subtle pain presentations in horses. That broader rehabilitation perspective aligns with the review’s central message: clinicians may need to think beyond joints and tendons when a horse presents with vague, shifting, or poorly localizing lameness. Still, the wider pain literature also shows active debate about how trigger points should be interpreted mechanistically, suggesting the field is still evolving. (horsesinsideout.com)

Why it matters: For veterinary professionals, this review is less about replacing standard lameness diagnostics than about widening the differential list earlier in the case. If trigger points can generate referred pain and gait asymmetry, then some horses may be exposed to repeated imaging, nerve blocks, or prolonged workups before muscle-based pain is considered. The practical implication is a more deliberate musculoskeletal exam that includes systematic palpation, attention to pain behaviors, and collaboration with rehabilitation and sports medicine teams when findings don’t cleanly match imaging or anesthesia results. The caution, though, is equally important: this is a review article, not a prospective clinical trial, and the field still needs stronger evidence on prevalence, diagnostic reliability, and treatment-linked outcomes before MTrP assessment can be standardized across practices. (frontiersin.org)

What to watch: The next step is likely prospective validation, especially studies testing whether structured myofascial exams improve diagnostic accuracy, predict response to therapy, or reduce inconclusive lameness workups. Watch, too, for efforts to standardize palpation criteria, pressure algometry, thermography, or other adjunctive tools, since one of the biggest barriers to broader adoption is still reproducibility in identifying these lesions across clinicians. (mdpi.com)