The Sport Horse Research Foundation

the Sport Horse Research Foundation

Awarded Grants & Research


Grantee: Fabrice Rossignol, DVM, Dipl ECVS
Year: 2020
Title: Assessment of Selective Laryngeal reinnervation (SLR) of the CAD muscle with the Ventral Branch of the Spinal Accessory Nerve (SAN) in horses with artificially induced RLN
Status: In Progress

Dr. Rossignol is refining a surgical technique that his team developed to correct laryngeal paralysis in horses presenting for roaring or laryngeal hemiplegia (partial laryngeal paralysis). Horses with laryngeal hemiplegia have decreased performance due to problems breathing during training and competing. This problem may affect horses used for racing and sports (all disciplines) at any level. The concept is to reinnervate the paralyzed laryngeal muscles rendering them functional again as compared to the traditional technique of surgically ‘opening’ or ‘tying back’ the paralyzed side of the larynx. Dr. Rossignol has been using this technique on more than 100 horses with great success. The SHRF funding will participate to this technique validation and standardization.


Recurrent laryngeal neuropathy (RLN) is well established as a common cause of poor performance in race and sport horses. RLN results in progressive atrophy of the ipsilateral intrinsic laryngeal muscles, including the cricoarytenoideus dorsalis muscle (CAD), resulting in a loss of arytenoid cartilage abduction at exercise and causing an inspiratory obstruction, turbulent airflow and abnormal noise production. Currently, the standard treatment for RLN remains prosthetic laryngoplasty, with the goal of permanently abducting the left arytenoid cartilage. Laryngoplasty, however, alters the initial laryngeal physiology and associated anatomical changes can lead to a fair number of complications following surgery, such as coughing, dysphagia and loss of arytenoid abduction. In the last two decades, research has been focusing on the restoration of physiological function of the CAD through reinnervation. The recently modified direct nerve implantation technique using the first and second cervical nerve is replacing the nerve-muscle pedicle technique. The observation of the long post-operative recovery and the necessity to work the horse at high intensity before stimulating the CAD muscle after a C1-C2 reinnervation, triggered the search for a possibly more adapted nerve to reinnervate the CAD muscle, that would allow a shorter rehabilitation period and already stimulate the CAD muscle during the recovery phase. The sternomandibularis muscle and the ventral branch of the large Spinal Accessory Nerve (SAN) are structures that can be well dissected and exposed, especially in the standing horse. Preliminary EMG studies have shown that this muscle is strongly activated at galop just before inspiration and more regularly at trot, but it is also triggered when the horse is grazing, which would allow stimulation of the CAD muscle while the horse is recovering in the field. So far, the results of SAN grafts performed on client owned horses alone or in combination with the C1-C2 nerve are very promising, but a clinical prospective study is missing to objectify these results.

The objectives of the study are 1) To describe a modified laryngeal reinnervation technique using the SAN for the treatment of laryngeal neuropathy in horses 2) To assess the capacity of SAN reinnervation to restore the abduction at exercise in horses with artificially induced RLN and 3) To demonstrate the quality of reinnervation at a muscular scale by histology.

Grantee: Pablo Espinosa-Mur, DVM, DACVS, DECVS
Year: 2018
Title: Radiographic and Ultrasonographic Findings of The Caudal Cervical Region in 105 Warmblood Jumpers
Status: Submitted For Publication

Cervical arthropathy in horses has been documented as a source of neck pain, stiffness, muscle atrophy, abnormal posture, poor performance, ataxia and lameness. Osteoarthritis (OA) at the cervical articular process is usually diagnosed with radiography, ultrasonography and nuclear scintigraphy. Osteoarthritis is a relatively common feature in sport horses. To the best of our knowledge, however, there are no reports in the literature describing the prevalence of cervical osteoarthritis in a normal population of sport horses. The main objective of this study was to report radiographic and ultrasonographic findings of the caudal cervical region in a population of sound and performing warmblood jumpers. Secondly, we studied the correlation between cervical facet OA seen on the radiographs and the presence of joint effusion and/or capsulitis on ultrasound. Finally, we determined the association between presence of OA, age and neck range of motion.

Grantee: Jennifer Symons, PhD
Year: 2018
Title: Comparing distal limb nuclear scinitgraphy of sport horses and racehorses
Status: Submitted For Publication

Just like their human counterparts, equine athletes in all equestrian disciplines are susceptible to injury when training and competing. Horses, however, engage in different biomechanical tasks based on their discipline. For instance, sport horses in jumping and dressage are required to negotiate turns in both directions, as well as collect and extend their stride length. Conversely, American racehorses gallop with larger stride lengths in straight lines and left turns. Differences in biomechanical tasks likely contribute to differences in horse limb loading (force magnitude and direction), and ultimately sites of injury. The purpose of this study is to examine differences in sites and incidence of injury between horses of different disciplines, specifically sport horses and racehorses. Nuclear scinitgraphy is an ideal imaging modality based on its high sensitivity and ease of imaging the entire skeleton. Study subjects include sport horses and racehorses presenting with lameness or poor performance that was investigated with nuclear scinitgraphy. Imaging reports will be reviewed for sites of increased radiopharmaceutical uptake (IRU). Each site of IRU will be recorded by location, identifying both the bone within the skeleton and the anatomical location within the bone. Each site of IRU will also be graded for severity and quality. IRU sites will be compared between sport horses and racehorses using relative risk. Similarly, IRU sites will be compared for sidedness (left, right, or bilateral) and fore/hind differences. Identifying differences in IRU sites will promote understanding of the relationship between discipline-specific biomechanical tasks and associated limb loading. Understanding these relationships may allow for future development of methods for injury prevention.


Fabrice Rossignol, DVM, Dipl ECVS

Fabrice Rossignol was graduated in 1994 from National veterinary school of Toulouse (South of France). He joined the equine clinic of Grosbois near Paris just after, and became partner in 1998. He followed an ECVS alternate training residency program between 2002 to 2007 and became an ECVS diplomate in 2010. Fabrice is a senior surgeon at the Equine clinic de Grosbois and has a partnership with Maisons-Alfort University and the Cirale. He has a 100% activity in surgery. He has a major interest in upper airway surgery and fracture repair. He is involved in several research projects such as the development of a laryngeal pacemaker and new techniques of laryngeal reinnervation. He is also a member of the AOVET expert group and Faculty since 2016 and is active in the development of new orthopedic implants.

Pablo Espinosa-Mur, DVM, DACVS, DECVS

Pablo Espinosa-Mur is a faculty surgeon at UC Davis. He obtained his Veterinary degree at the University Complutense of Madrid, Spain. He completed an Internship in Equine Medicine and Surgery at the University of Montreal, Canada. After this internship, Pablo started working with Dr. Philippe Benoit in a Lameness and Orthopedic referral practice in Paris. He then completed an equine surgery internship at Milton Equine Hospital in Canada before starting his surgical residency at UC Davis. Dr. Espinosa-Mur is currently working on several research projects including a novel technique for injection of the navicular bursa by ultrasonographic guidance. He has also worked on a technique to perform desmotomy of the palmar annular ligament in the standing horse using a minimally invasive approach and ultrasonographic assistance. This year Dr. Espinosa-Mur will present the results of the neck study at ACVS and AAEP. Pablo is also actively collaborating with Dr. Mathieu Spriet on the application of positron emission tomography as diagnostic tool in lame horses. Pablo has a specific interest in lameness, diagnostic imaging, regenerative therapies and orthopedic surgery.

Jennifer Symons, PhD Biomedical Engineer, Musculoskeletal Biomechanics Researcher

Jennifer Symons, PhD is an equestrian, scientist, and engineer that is interested in biomechanics of equine athletes. She studied mechanical and biomedical engineering at the University of California at Davis, and performed research within the J. D. Wheat Veterinary Orthopedic Research Laboratory spanning tissue mechanics to whole body dynamics. With the guidance of Susan Stover, DVM, PhD, DACVS, Jen developed and validated a combined forelimb and race surface computational model to understand the effect of race surface mechanical properties on racehorse limb dynamics during gallop. Jen currently works as an Assistant Professor of Mechanical and Biomedical Engineering at the University of Portland. Additionally, she is focused on extending her research knowledge and experience to other equine disciplines, particularly showjumping and dressage. Her goal is to identify equine athlete injuries and their causes, as well as develop methods for injury prevention and optimal performance.