Musculoskeletal disorders are a leading cause of lost training days, diminished performance, and early retirement in horses across disciplines. The latest special focus section of the Equine Veterinary Journal (EVJ) shines the spotlight on the impact of such disorders in sport horses, providing a useful collective resource on recent advances in diagnostic tests and therapeutic approaches.
The Special Focus section, edited by Maarten Oosterlinck and Rhiannon Morgan with guest editors Kyla Ortved and Hilary Clayton, comprises 21 retrospective studies, case series and prospective clinical trials from some of the world’s leading researchers in fields relevant to musculoskeletal disorders. The studies are presented in three sections; Aetiology, diagnostics and therapeutics, all of which should help improve general understanding of factors influencing musculoskeletal health in sport horses. A comprehensive foreword from the team of editors is included with the Special Focus, succinctly summarising all the papers within the collection. They have also recorded an accompanying podcast.
Epidemiology and aetiology
Osteochondrosis is the most common developmental orthopaedic disease in horses, with vascular failure being shown to lead to osteochondrosis lesions. Olstad summarises over a decade of research, emphasising how vascular failure can lead to diverse manifestations of osteochondrosis including osteochondritis dissecans.
Equine fatalities in equestrian eventing
Most falls and injuries during eventing occur during the cross-country phase. Cameron-Whytock et al. report on equine fatalities in the sport of eventing over 25 years, revealing that musculoskeletal injuries were the cause of death in 36.4% of cases.
Musculoskeletal injuries associated with lameness in Australian campdraft horses
Campdrafting is a popular sport in Australia that involves demonstrating the horse and rider’s ability to control a cow and ride a set pattern. From the medical records of 267 campdrafting horses Argue and Labens identified that the distribution of lameness was 53% forelimb (13% bilateral) and 41% hindlimb (7% bilateral).
Osseous pathologic changes in the thoracic region of the equine vertebral column
Vertebral pathological changes have long been related to poor performance. Spoormakers et al. used CT to detect osseous spinal pathologies in cadavers from three breeds of different sizes. Warmbloods having more lesions than horses of the two smaller breeds studied; specifically, more osteoarthritis, spondylosis and spinous process impingement.
Spinal articular dysfunction
This involves articular process joint hypomobility with impaired function of neural and connective tissues. Patricio et al. conclude that early identification and correction, followed by specific rehabilitation and strengthening may prolong the athletic careers of affected horses.
Equine suspensory ligament injuries
The equine suspensory ligament (SL) is a frequent site of injury in sport horses. Guest et al. review the composition, structure and mechanical properties of the SL concluding that a variety of treatments are available but the long-term outcome remains uncertain.
Diagnostics
Quantifying head and withers movement asymmetry equine movements are rarely completely symmetrical even in horses that are apparently not lame. Taddey et al. report IMU data for head and withers vertical displacement variables in sound horses and horses with naturally occurring forelimb lameness.
Myopathy
Most myopathy studies to date have focused on Thoroughbreds and Warmbloods. Hansen et al. describe a novel, chronic, idiopathic myopathy in a cohort of Icelandic horses presenting with poor performance and/or multi-limb lameness.
Metabolomic and proteomic stratification
Osteoarthritis (OA) is the most common cause of chronic lameness in horses with diagnosis often made after substantial joint damage has occurred. Anderson et al. investigate synovial fluid metabolomic and proteomic profiles associated with varying grades of OA in both Thoroughbred racehorses and mixed-breed horses highlighting promising targets for future diagnostic assays and therapeutic development.
In the quest to investigate therapeutics that may produce significant disease-modifying effects, Munevar Luque et al.evaluate the safety and efficacy of pooled equine umbilical cord-derived mesenchymal stem cells (eCB-MSCs) combined with hyaluronic acid (HA), compared to HA alone.
Computed tomography
The growing adoption of technologically advanced computed tomography (CT) scanners and equipment has improved accessibility of imaging the proximal limb and axial skeleton of the horse. Two comprehensive studies from Ogden et al. report the technical aspects, safety, anatomical variations, and pathological findings.
Another application of computed tomography is myelography for the diagnosis of extradural spinal cord compression. Hellige et al. describe inter and intravertebral ratios and distribution of contrast columns of the cranial cervical spine in Warmblood horses with no spinal pathology.
Another technological advancement in computed tomography (CT) is the development of scanners capable of imaging the distal limb in standing horses. Nagy et al. explore the diagnostic value of using standing fan-beam CT and standing low-field MRI in combination while Szabó et al. look at standing CT measurements of the hooves in non-lame horses.
Magnetic Resonance Imaging
MRI has become a crucial tool in diagnosing deep digital flexor tendon (DDFT) injuries. Scharf et al. review magnetic resonance imaging (MRI) of deep digital flexor tendinopathy. Peeters et al. discuss the MRI evaluation of the palmar/plantar ligaments of the proximal interphalangeal joint (PL-PIPJ) using low-field standing MRI. Bowkett-Pritchard et al. examine the agreement between low-field MRI and digital radiographic measurements of fore feet.
Therapeutics
Trimming hooves seeks to balance the hooves to optimise performance and soundness but may affect multiple aspects of hoof balance and exacerbate musculoskeletal injury. Seery et al. address the link between morphology and loading of the hoof by measuring and comparing external hoof dimensions with pressure distribution on the solar surface before and after trimming
Desmotomy
The superficial digital flexor tendon (SDFT) is one of the most common soft tissues injured in equine athletes. Blatter et al. investigate the outcome of tenoscopic desmotomy of AL-SDFT in Warmblood horses with SDF tendinopathy.
Caudal wedge ostectomy
Overriding or impinging dorsal spinous processes (kissing spines) are a frequent source of thoracolumbar pain in horses. Connaughton et al. present an experimental comparison of caudal and cranial wedge ostectomy techniques.
“This special focus brings together the latest science and knowledge on multiple aspects of the diagnosis and treatment of Musculoskeletal disorders in sport horses” said Maarten Oosterlinck, deputy editor of the EVJ. “The practical, evidence-based studies present imperative reading for veterinary practitioners, to support their goal of providing the most advanced diagnostics and therapeutic approaches for sport horses with musculoskeletal issues.”
The EVJ special focus issue on Musculoskeletal disorders in Sport horses can be found here.
The podcast in which the editors discuss the issue can be found here.