The larynx in horses is a complex anatomical structure located in the throat, playing a critical role in respiration, phonation, and airway protection. It consists of cartilages, muscles, and ligaments that work together to regulate airflow into the trachea and produce vocal sounds. The equine larynx is susceptible to various conditions, such as laryngeal hemiplegia, which can impact a horse's breathing and performance. This page aggregates peer-reviewed research studies and scholarly articles that explore the anatomy, function, disorders, and clinical management of the larynx in horses, providing insights into diagnostic techniques and therapeutic interventions.
Bolfa P, Cercone M, Dennis MM, Conan A, Grevemeyer B, Ducharme NG.Equine arytenoid chondritis causes airway obstruction and abnormal upper airway noise due to a space-occupying lesion(s) and decreased abduction. Our objective was to compare clinical scores and ultrasonographic findings with gross and microscopic lesions of naturally occurring arytenoid chondritis, in order to guide surgical treatment. Seventeen naturally affected horses with advanced/severe chronic arytenoid chondritis and 4 control arytenoid cartilages were evaluated after partial arytenoidectomy. Cartilages were sectioned caudal to the corniculate process and the body of each arytenoid was...
Genton M, Robert C, Jerbi H, Huet H, Cordonnier N, Vitte-Rossignol A, Perkins JD, Rossignol F.To describe the innervation of the thyrohyoideus (TH) muscle and to confirm our findings with stimulation of first cervical (C1) nerve branches. Methods: Ex vivo phase 1 and clinical phase 2. Methods: Fourteen head and neck specimens and 17 client-owned horses. Methods: In phase 1, the cranial nerve (CN) XII and the C1 nerve were dissected with their branches in 20 dissections were performed on 14 specimens (6 left and right side and 8 only left or right) Anatomy was noted. Samples of nerve bifurcations were collected for histological confirmation of anatomical findings. First cervical nerve b...
Lynch NP, Jones SA, Bazley-White LG, Wilson ZF, Raffetto J, Pfau T, Cheetham J, Perkins JD.To identify the degree of left arytenoid cartilage (LAC) abduction that allows laryngeal airflow similar to that in galloping horses, assess 2-D and 3-D biomechanical effects of prosthetic laryngoplasty on LAC movement and airflow, and determine the influence of suture position through the muscular process of the arytenoid cartilage (MPA) on these variables. Methods: 7 equine cadaver larynges. Methods: With the right arytenoid cartilage maximally abducted and inspiratory airflow simulated by vacuum, laryngeal airflow and translaryngeal pressure and impedance were measured at 12 incremental LAC...
Grzeskowiak RM, Schumacher J, Mulon PY, Steiner RC, Cassone L, Anderson DE.Rostral laryngeal advancement, also known as laryngeal tie-forward, is used to treat horses for intermittent dorsal displacement of the soft palate and has a morbidity rate of about 6%. We hypothesized that a novel laryngeal clamp would prevent morbidity associated with the sutures tearing through the thyroid cartilage. Larynges (n = 35 horses) were used for ex vivo testing. For uniaxial testing, 15 equine larynges were tested in one of three laryngeal tie-forward constructs [standard laryngeal tie-forward; modified laryngeal tie-forward using a suture-button; and modified laryngeal tie-forwar...
Satoh M, Higuchi T, Inoue S, Miyakoshi D, Kajihara A, Gotoh T, Shimizu Y.Recent studies have assessed the cricoarytenoideus dorsalis muscle (CAD) using transoesophageal ultrasonography in equine recurrent laryngeal neuropathy (RLN). We assessed the CAD using the external transcutaneous ultrasound technique, which may constitute an easier method in horses. Objective: To evaluate ultrasonographic imaging of the left cricoarytenoideus dorsalis muscle (LCAD) and right cricoarytenoideus dorsalis muscle (RCAD) as a diagnostic tool for RLN using the transcutaneous ultrasound technique. Methods: Cross-sectional study. Methods: The axial plane thickness, cross-sectional are...
Kallmyr A, Giving EM, Moen LO, Øverlie M, Holm T, David F.To describe a resection technique of the alar folds in the standing horse. Methods: Retrospective case study. Methods: Eight Standardbred racing trotters. Methods: Horses in which alar fold collapse had been diagnosed between 2017 and 2018 were included in this study. All horses underwent alar fold resection under standing sedation and regional anesthesia with a bipolar electrosurgical open sealer/divider device (LigaSure). Intraoperative and postoperative complications were recorded. A Wilcoxon signed-rank test was used to compare differences in median prize money earning pre-surgery and post...
Luedke LK, Cheetham J, Mohammed HO, Ducharme NG.To evaluate the efficacy of various treatments for dysphagia after laryngeal surgery. Methods: Retrospective. Methods: Horses treated for dysphagia after laryngeal surgery. Methods: Medical records of horses treated for dysphagia after prosthetic laryngoplasty (PLP) or partial arytenoidectomy (PA) were reviewed. Signalment, prior surgery, preoperative videoendoscopic diagnosis, and surgical treatments were recorded. Short- and long-term follow-up were obtained. Chi-square and logistical regression were performed to correlate independent variables and outcomes. Results: Forty-four percent of ho...
Toft K, Kjeldsen ST, Otten ND, van Galen G, Fjeldborg J, Sinding M, Hansen S.Flexion of the horse's head and neck during dressage riding reduces the pharyngeal lumen with the risk of increased upper airway resistance and upper airway obstructions. According to the Fédération Equestre Internationale, hyperflexion is achieved through force, whereas the position low-deep-round is nonforced. The objectives of this study were to evaluate (1) applied rein tension and (2) dynamic structural disorders in the upper airways in dressage horses in different gaits and different head-neck positions (HNPs). Overground endoscopy (OGE) and rein tension were evaluated in 13 clinically...
Tucker ML, Sumner D, Reinink SK, Wilson DG, Carmalt JL.To compare laryngeal impedance, in terms of air flow and pressure, following arytenoid corniculectomy (COR) versus 3 other airway interventions (left-sided laryngoplasty with ipsilateral ventriculocordectomy [LLP], LLP combined with COR [LLPCOR], and partial arytenoidectomy [PA]) performed on cadaveric equine larynges with simulated left recurrent laryngeal neuropathy (RLN) and to determine whether relative laryngeal collapse correlated with the interventions performed. Methods: 28 cadaveric equine larynges. Methods: Each larynx in states of simulated left RLN alone and with airway interventio...
Beste KJ, Ortved KF, Rossignol F, Ducharme NG.To describe the use of a silicone-covered laser guide and diode laser for surgical correction of epiglottic entrapment and report postoperative outcomes in horses with epiglottic entrapment. Methods: Retrospective case series. Methods: Thoroughbred and standardbred racehorses (n = 29) with epiglottic entrapment. Methods: A silicone-covered laser guide was placed endoscopically to direct the diode laser cutting action during transection of the entrapping subepiglottic membrane and to act as a physical barrier between the membrane and the epiglottic cartilage. Postoperative complications and tra...
Jones S, Franklin S, Martin C, Steel C.There is limited knowledge of the breathing strategy and impact on the patency of the upper respiratory tract (URT) in swimming horses. Objective: To describe the respiratory responses and endoscopic appearance of the URT during tethered swimming in horses. Methods: Prospective descriptive study. Methods: Ten race-fit horses, with no history of URT obstruction, were examined during tethered swimming. Endoscopic examination, heart rate, sound recordings and above and below water video recordings were obtained. Plasma lactate concentration was measured before and 5 min after swimming and trache...
Miller S, Carstens A.Laryngoplasty is commonly used to treat laryngeal hemiplegia in Thoroughbred racehorses. Evaluation of the success of the laryngoplasty is traditionally determined using endoscopy. Laryngeal ultrasonography and normal ultrasonographic appearance have been reported in the standing horse, but post-laryngoplasty and ventriculectomy ultrasonographic evaluation has limited literature coverage. A prospective case series of 10 Thoroughbred racehorses with left laryngeal hemiplegia was examined ultrasonographically and endoscopically prior to 3-10 days, 30-50 days, and 6-12 months after laryngoplasty ...
Lee SK, Lee I.Twelve Thoroughbred racehorses were diagnosed as epiglottic entrapment at the Korea Racing Authority equine hospital. Four different surgical correction techniques were used to treat epiglottic entrapment: the transnasal hook bistoury, transoral unshielded hook bistoury, transnasal shielded hook bistoury, and transendoscopic laser techniques. Eleven cases were surgically resolved eventually, with one case of recurrence. Five complications related to surgical correction occurred: a severe nasal passage laceration and bleeding (n=1), epiglottic laceration (n=1), epiglottis tip burns (n=2), and m...
Chesworth M, Brandenberger O, Cheetham J, Windley Z, Schumacher J, Cochran K, Piercy RJ, Perkins JD. To investigate the effect of the transverse arytenoid ligament (TAL) on abduction of the arytenoid cartilage when performing laryngoplasty. Modified prosthetic laryngoplasty was performed on right and left sides of 13 cadaver larynges. Increasing force was sequentially applied to the left arytenoid cartilage at 3 N intervals from 0-24 N, when the force on the right arytenoid cartilage was either 0 or 24 N, before and after TAL transection. Digital photographs of the rostral aspect of the larynx were used to determine the left arytenoid abduction angles for these given force combinations and ...
Hibi H, Hatama S, Obata A, Shibahara T, Kadota K.A case of laryngeal squamous cell carcinoma (SCC) and squamous papilloma in a 19-year-old Thoroughbred stallion is described. The animal exhibited severe wheezing caused by laryngopharyngeal stenosis. Histological examination identified laryngeal, laryngotracheal, and guttural pouch tumor masses consisting of areas of SCC. In the epiglottic lesion, the overlying epithelium was replaced by papilloma cells, and superficial cells frequently had nuclear inclusion bodies that expressed oncoprotein E6, which is characteristic of high risk human papillomaviruses. The papillomatous epithelium was cont...
Curtiss AL, Aceto H, Embertson RM.Epiglottic entrapment can occur in yearling Thoroughbreds (TB); however, race performance following surgical correction is unknown. Objective: To determine the race performance of horses treated surgically for epiglottic entrapment as yearlings as compared to an untreated cohort. A second objective was to identify risk factors for treated horses not racing post-operatively. Methods: Retrospective cohort and case-control studies. Methods: Medical (1989-2014) and race records of 66 treated TB racehorses were reviewed. Observed abnormalities on pre- and post-operative endoscopic images and surgic...
Curtiss AL, Parente EJ.To report an epiglottopexy technique for the treatment of epiglottic retroversion (ER) in 2 horses. Methods: Case report. Methods: A 2-year-old thoroughbred gelding and a 6-year-old standardbred gelding, both with ER. Methods: Epiglottic retroversion was diagnosed via exercising endoscopic examination in both horses. Epiglottopexy technique was performed in both cases. Results: Both horses returned to previous racing class within 1 year after surgery. Repeat exercising endoscopy of 1 horse 6 months postoperatively revealed resolution of the ER. Conclusions: Epiglottopexy should be consider...
Satoh M, Higuchi T, Inoue S, Miyakoshi D, Gotoh T.Assessment of the cricoarytenoideus dorsalis muscle (CAD) in horses using a transesophageal ultrasound, computed tomography, or magnetic resonance imaging is available in a limited number of hospitals. This study assessed the ease of ultrasonographic imaging of the CAD using an external transcutaneous technique in horses. After confirmation of the CAD in the cadavers, ultrasonography in twenty live horses was carried out using a transcutaneous approach. In live horses, ultrasonographic imaging of the CAD was possible by pushing the larynx from the opposite side with the other hand. It is belie...
Gray SM, Gutierrez-Nibeyro SD, Secor EJ.To report our experience with partial arytenoidectomy in sedated standing horses. Methods: Retrospective study. Methods: Fourteen client-owned adult horses. Methods: The medical records (2013-2017) of horses treated with unilateral partial arytenoidectomy while standing and sedated were reviewed. Demographics, endoscopic findings, previous treatments, and outcome after surgery were investigated and recorded. Results: Thirteen horses had unilateral left-sided recurrent laryngeal neuropathy (RLN) and 1 horse had bilateral RLN. Five horses had a previous failed prosthetic laryngoplasty. Left-side...
Cercone M, Hokanson CM, Olsen E, Ducharme NG, Mitchell LM, Piercy RJ, Cheetham J.The dorsal cricoarytenoid (DCA) muscles, are a fundamental component of the athletic horse's respiratory system: as the sole abductors of the airways, they maintain the size of the rima glottis which is essential for enabling maximal air intake during intense exercise. Dysfunction of the DCA muscle leads to arytenoid collapse during exercise, resulting in poor performance. An electrodiagnostic study including electromyography of the dorsal cricoarytenoid muscles and conduction velocity testing of the innervating recurrent laryngeal nerves (RLn) was conducted in horses with normal laryngeal fu...
Suarez-Fuentes DG, Tatarniuk DM, Caston SS, Bell CD, Loinaz RJ, Hostetter JM.To evaluate the efficacy and safety of a transendoscopic monopolar electrosurgical triangle-tip knife as instrumentation to perform unilateral ventriculocordectomy (VC) in healthy adult horses. Methods: In vivo experimental study. Methods: Nine horses donated for medical conditions unrelated to respiratory system. Methods: The triangle-tip knife was applied in contact fashion. Left VC was performed under standing sedation. Endoscopic images of the upper airway were graded for inflammation by 2 masked surgeons preoperatively and immediately, 24 hours and, in 2 cases, 7 and 14 days postopera...
Ahern BJ, Lukas E, Lam K, Wilke E, Bertin FR, Van Eps A, Franklin S.To evaluate a prototype dynamic laryngoplasty system (DLPS) in a static airflow model. Methods: Experimental. Methods: Ten equine larynges. Methods: The right arytenoid was fixed in abduction in all specimens. A left-sided laryngoplasty was performed with No. 2 Fiberwire and a FASTakII anchor. Each larynx was tested in a static airflow model. The system was adjusted to a flow rate of 55 L/s and prelaryngeal pressure of 12 mm Hg prior to testing in maximal arytenoid abduction. In phase 1, the left suture was loosened, shortened, and tested in 3-mm steps from 0 to 30 mm. In phase 2, the su...
Sekhar V, Wong E, Elhassan HA, Singh N.Mules and other equine species have been used in warfare for thousands of years to transport goods and supplies. Mules are known for 'braying', which is disadvantageous in warfare operations. This article explores the fascinating development of surgical techniques to stop military mules from braying, with particular emphasis on the key role played by the otolaryngologist Arthur James Moffett in devoicing the mules of the second Chindit expedition of World War II. Methods: The PubMed database (1900-2017) and Google search engine were used to identify articles related to devoicing mules in the m...
Sandersen C, Ceusters J, Fourez A, Tosi I, Graide H, Lejeune JP, Serteyn D.Recurrent laryngeal neuropathy (RLN) commonly affects horses and is characterized by abnormal respiratory sounds and exercise intolerance. The recurrent laryngeal nerve shows lesions of demyelination. The benefit of applying stem cells to demyelinated nerves has been demonstrated in various animal models. The aim of the study was to test the feasibility and safety of a peri-neuronal injection of autologous muscle-derived mesenchymal stem cells to the left recurrent laryngeal nerve in healthy horses by using an electrical nerve stimulator. Muscle-derived stems cell are obtained from five health...
Brandenberger O, Martens A, Robert C, Wiemer P, Pamela H, Vlaminck L, Barankova K, Haspeslagh M, Perkins JD, Ducharme N, Rossignol F.To describe the anatomy of the entry to the equine esophagus (vestibulum esophagi) and to assess the risk of penetrating its adventitia and/or lumen during laryngoplasty. Methods: Ex vivo cadaveric study. Methods: Five isolated equine larynges and 39 equine head and neck specimens. Methods: The anatomy of the vestibulum esophagi was studied by dissection of 5 cadaver specimens. Then, a bilateral laryngoplasty was performed, including 5 suture placements through the muscular processes, caudal, rostral, and sagittal, with straight and curved needles. Two of the 3 surgeons performing the implanta...
Barakzai SZ, Wells J, Parkin TDH, Cramp P.Unilateral ventriculocordectomy (VeC) is frequently performed, yet objective studies in horses with naturally occurring recurrent laryngeal neuropathy (RLN) are few. Objective: To evaluate respiratory noise and exercising overground endoscopy in horses with grade B and C laryngeal function, before and after unilateral laser VeC. Methods: Prospective study in clinically affected client-owned horses. Methods: Exercising endoscopy was performed and concurrent respiratory noise was recorded. A left-sided laser VeC was performed under standing sedation. Owners were asked to present the horse for re...
Ahern BJ, Lim YW, van Eps A, Franklin S.To determine the effect of a prototype dynamic laryngoplasty system (DLPS) on arytenoid abduction. Methods: In vitro experimental. Methods: Ten equine larynges. Methods: Dissected larynges were mounted, and the right arytenoid was maximally abducted for testing. A left-sided laryngoplasty (LP) was performed by using a strand of No. 2 FiberWire and a FASTakII anchor. Phase 1 involved tightening the suture, without the DLPS device in place, in 1-mm increments and acquiring a digital image of the rima glottidis at each increment. Phase 2 involved tying the suture with the DLPS in place at a left ...
Kieffer PJ, Aceto H, Stefanovski D, Parente EJ.To assess the outcome of transendoscopic laser surgery for the treatment of epiglottic entrapment (EE) and determine the influence of preoperative morphological characteristics on outcomes. Methods: Retrospective cohort study. Methods: Thoroughbred racehorses treated with transendoscopic laser surgery (n = 66) and untreated cohorts (n = 132). Methods: Medical, surgical, and race records of 66 horses treated with transendoscopic laser surgery were compared with untreated cohorts randomly selected from their last race presurgery. Postsurgery data were collated as number of starts and rac...
Parente EJ.Many abnormalities of the upper airway that can inhibit performance are determined on a critical resting endoscopic evaluation. Some dynamic abnormalities can only be seen during an exercising endoscopic evaluation, which should be performed whenever the history of abnormal noise or performance limitations is not completely consistent with the resting endoscopic findings. Head and neck position may play a critical role in the evaluation process and the exact position during performance should be reproduced during the clinical examination to definitively define the abnormality. Treatments and p...
Garrett KS, Pierce SW, Embertson RM, Stromberg AJ.OBJECTIVE-To determine the association between results of endoscopic evaluation of arytenoid function (AF) and epiglottic structure (ES) in Thoroughbred yearlings and racing performance at 2 to 4 years of age. DESIGN-Retrospective case series. ANIMALS-2,954 Thoroughbred yearlings. Procedures-Records of yearlings that had endoscopic evaluation of the larynx between 1998 and 2001 were obtained, and results were graded by use of standardized scales. A modified Havemeyer scale (grade I, II.1, II.2, III, or IV) was used to evaluate AF; ES was graded on a scale of 0 to IV. Records were annotated if ...
Rossignol F, Brandenberger O, Perkins JD, Marie JP, Mespoulhès-Rivière C, Ducharme NG.In horses, the only established method for reinnervation of the larynx is the nerve-muscle pedicle implantation, whereas in human medicine, direct nerve implantation is a standard surgical technique for selective laryngeal reinnervation in human patients suffering from bilateral vocal fold paralysis. Objective: (1) To describe a modified first or second cervical nerve transplantation technique for the treatment of recurrent laryngeal neuropathy (RLN) in horses and (2) evaluate the outcomes of reinnervation using direct nerve needle-stimulation of the first cervical nerve and exercising endosco...
Heath RB, Steffey EP, Thurmon JC, Wertz EM, Meagher DM, Hyyppa T, Van Slyke GL.Sequelae of routine orotracheal intubation under clinical conditions were characterised in 38 healthy horses presented at three veterinary medical teaching hospitals. Four of these were necropsied and their tissues studied histologically. To minimise variation, 30 mm id cuffed silicone endotracheal tubes or Cole cuffless tubes were used in all patients. Fibreoptic endoscopic examination of upper respiratory and tracheal areas was accomplished pre-intubation, immediately post extubation and after 24 h. Endoscopy revealed that intubation was associated with laryngeal and/or tracheal lesions in a...
Anderson BH, Kannegieter NJ, Goulden BE.An endoscopic survey of young race horses was performed to examine the prevalence and character of laryngeal movements during quiet respiration. The main aim was to determine whether those arytenoid movements which could possibly reflect the efficiency of left dorsal cricoarytenoid muscle function changed over a period of time. Of the 452 horses examined, 439 were Thoroughbreds and 23 were Standardbreds, 250 were less than 2 years of age (6-21 months), and 202 were 2 years old. One hundred and nine of these horses were examined again 16 months later. Arytenoid movements were given one of four ...
Robinson NE, Sorenson PR.Obstruction of the upper and lower airways is common in horses. In the upper airway, paresis of abductor muscles of the nares and larynx allows inspiratory collapse of soft tissues, which is accentuated by factors increasing upper airway resistance and by high inspiratory flow rates. Intrapulmonary airway obstruction occurs due to accumulation of secretions, release of chemical mediators in response to a variety of stimuli, and parasympathetic stimulation of airways. Obstruction of large airways increases the work of breathing, whereas obstruction of small airways may cause no measurable incre...
Morris EA, Seeherman HJ.Forty-six racehorses with a history of poor performance underwent endoscopic evaluation of laryngeal and pharyngeal function while exercising on a high-speed treadmill. This evaluation allowed the definitive diagnosis of intermittent or continual upper respiratory tract obstruction as a cause of poor performance, as well as the documentation of the dynamic functional anatomy of the obstruction. Ten of the horses (22%) were determined to have a functional abnormality of the upper respiratory tract. These abnormalities included epiglottic entrapment (1 horse), persistent dorsal displacement of t...
Zebisch A, May A, Reese S, Gehlen H.Hyperflexion, that is the strong deflection of the horse's head, poll and neck, is a prevalent training technique in equitation. Hyperflexion has come under criticism in recent years for being suspected of affecting the horses' well-being contrary to animal welfare. The goal of the present study is a comparison between the impacts of different poll-neck positions on findings in the upper respiratory tract of ridden horses. For this purpose, video recordings of the larynges of 14 horses were taken using an overground endoscope. The videos were recorded at rest and during three different riding ...
Yamamoto Y, Atoji Y, Hobo S, Yoshihara T, Suzuki Y.To discuss the significance of laryngeal sensation on various disorders of the horse, we studied the morphological and topographical characteristics of sensory structures in the laryngeal mucosa using immunohistochemistry and immunoelectron microscopy. Various sensory structures, i.e. glomerular endings, taste buds and intraepithelial free nerve endings, were found in the laryngeal mucosa by immunohistochemistry for protein gene product 9.5 (PGP 9.5) and neurofilament 200kD (NF200). Glomerular nerve endings were distributed mainly in the epiglottic mucosa; some endings were also found in the a...
Ducharme NG, Hackett RP, Gleed RD, Ainsworth DM, Erb HN, Mitchell LM, Soderholm LV.We hypothesized that changes in pleural pressure induced by resistive breathing would affect transmural pulmonary artery, pulmonary capillary, and pulmonary wedge pressures. Seven horses were assigned to exercise with each of 4 upper respiratory resistive loads in random order at intervals of at least 2 days: 1) control--no added resistive loads; 2) inspiratory resistive load (Iobst)--left laryngeal hemiplegia; 3) expiratory resistive load (Eobst)--one-way valve in the right nostril; and 4) combined inspiratory and expiratory resistive loads (CIEobst)--left nostril occlusion. On each occasion,...
Jansson N, Ducharme NG, Hackett RP, Mohammed HO.To examine the effect of cordopexy, laryngoplasty, and cordopexy combined with a modified laryngoplasty on airway mechanics. Methods: Experimental airway mechanics were determined by subjecting equine cadaveric larynges to airflows similar to inspiratory airflow of exercising horses. Methods: Twenty equine larynges. Methods: Using cadaveric larynges, we developed and tested a new technique of arytenoid cartilage abduction. All larynges had the right arytenoid cartilage abducted to mimic the degree of arytenoid abduction that occurs at maximal exertion in live horses. Three surgical techniques ...
Ducharme NG, Hackett RP, Fubini SL, Erb HN.Twenty Thoroughbred and Standardbred horses underwent endoscopic evaluation of arytenoid cartilage movement twice within 1 week. Each time, a flexible endoscope was passed without sedation through the right nostril and the left nostril, and through the right nostril 5 minutes after administration of xylazine hydrochloride (0.55 mg/kg or 1.1 mg/kg intravenously). Laryngeal cartilage movement was videorecorded. All videotaped images were reviewed by three veterinarians and subjectively placed in one of four grades. The intraobserver agreement rate varied from 52.6% for examination under sedation...
Durando MM, Martin BB, Hammer EJ, Langsam SP, Birks EK.The primary goal was to investigate the relationship between dynamic upper airway abnormalities and arterial blood gas tensions during exercise. Horses that completed a high-speed treadmill examination consisting of upper-airway videoendoscopy, blood gas evaluation and electrocardiogams and, postexercise, echocardiograms and tracheal washes, were included. An age-matched group of fit, healthy Thoroughbreds, trained to run on a high-speed treadmill, served as controls for blood gas values at specific exercise speeds. One hundred and nineteen horses completed the treadmill examination. Sixty (50...
Dixon J, Smith K, Perkins J, Sherlock C, Mair T, Weller R.Melanomas are one of the most common neoplasms in the horse and are frequently found in the head region. There is a genetic predisposition in horses with a gray hair coat. Computed tomography (CT) is frequently used in referral practice to evaluate the equine head but there are few reports describing the CT appearance of melanomas in this location. The aim of this retrospective, case series study was to describe characteristics in a group of horses with confirmed disease. Case records from two referral hospitals were reviewed, and 13 horses were identified that had undergone CT of the head, wi...
Passman SN, Cheetham J, Bonassar LJ, Ducharme NG, Rawlinson JJ.Upper airway obstruction is a common problem in the performance horse as the soft tissues of the larynx collapse into the airway, yet there is a paucity of information on biomechanical properties for the structural cartilage components. Objective: To measure the geometry and compressive mechanical properties of the hyaline cartilage to improve understanding of laryngeal function and morphology. Methods: A total of 11 larynges were harvested from Thoroughbred and Standardbred racehorses. During gross dissection, linear dimensions of the cricoid were obtained. From both the cricoid and arytenoid...
López-Plana C, Sautet JY, Pons J, Navarro G.Quantitative measurements were made on cross-sectional preparations of the distal part of the recurrent laryngeal nerve (RLN) from nine young mixed-breed horses to establish reference values for the total number of myelinated fibres, mean fibre diameter and percentage of thickest fibres (over 9.5 microns) and to delineate diameter distribution curves. The total number of myelinated fibres, mean fibre diameter and percentage of thickest fibres for the left RLN were significantly lower than those of the right RLN (P < 0.005). The distribution of fibres was unimodal. The fibre diameter ranged ...
Manohar M, Goetz TE.Exercise-induced pulmonary hemorrhage (EIPH) is a common occurrence in racehorses. The objective of this study was to compare pulmonary vascular pressures of healthy Thoroughbred horses with and without postexertion endoscopically detectable fresh blood in the trachea. The nasopharynx, larynx, and trachea (down to the carina) of horses were examined weekly with an endoscope 55-60 min postexertion, and the diagnosis of EIPH was confirmed by the presence of fresh blood in the trachea. Measurements of heart rate and right atrial, pulmonary arterial, and pulmonary arterial wedge pressures were mad...
Collins N, Milne E, Hahn C, Dixon P.The establishment of a single validated endoscopic laryngeal grading system for assessing recurrent laryngeal neuropathy (RLN) is desirable to facilitate direct comparisons between the findings of different clinical and research groups worldwide. The objective of this study was to assess the relationship between the Havemeyer endoscopic laryngeal grading system and histopathological changes consistent with RLN in the left cricoarytenoideus dorsalis (CAD) muscle of horses of different breeds with a full range of clinical severities of RLN, i.e., from normal endoscopic laryngeal function to comp...
Lechartier A, Rossignol F, Brandenberger O, Vitte A, Mespoulhès-Rivière C, Rossignol A, Boening KJ.To compare mechanical properties of 2 techniques with a conventional technique for anchoring the muscular process in a laryngoplasty procedure. Methods: Experimental ex vivo study. Methods: Equine larynges (n = 60). Methods: A single loop (SL), a screw (SC), and a double loop technique (DL) were compared. Constructs were subjected to cyclic loading, oscillating from 5 to 50 N for 3000 cycles, followed by a single cycle to failure test. Mean distraction, load at failure, stiffness, and failure mode were compared between groups. Results: Mean ± SD distraction in cyclic loading was greater for D...
Strand E, Skjerve E.Many horses demonstrate dynamic collapse of more than one upper respiratory tract (URT) structure during high-speed treadmill videoendoscopy (HSTV). Objective: To report the frequency of complex dynamic URT collapse in harness racehorses and determine if an association exists between occurrence of certain disorders. Methods: Retrospective study of 99 Standardbreds and Coldblooded trotters that had one or more dynamic URT disorders identified during HSTV between 1998 and 2006. The horses underwent HSTV using a protocol that included periods of free head carriage and poll flexion until fully fat...
Brown JA, Hinchcliff KW, Jackson MA, Dredge AF, O'Callaghan RA, McCaffrey JR, Slocombe RF, Clarke AF.Little information is available regarding the prevalence of abnormalities of the upper airway and their association with performance in the general population of Thoroughbred racehorses. Objective: To describe the prevalence of selected abnormalities of the upper airway and their association with performance in Thoroughbred racehorses in Australia. Objective: That abnormalities of the upper airway of Thoroughbred racehorses are associated with poor race performance. Methods: Rhinolaryngoscopy was performed after racing and presence and characteristics of abnormalities of the larynx and pharynx...
Dean PW, Nelson JK, Schumacher J.Cartilage retention strengths of laryngoplasty prostheses were compared in larynges of 2-, 3-, and 4-year-old horses, using doubled polyester and expanded polytetrafluoroethylene prostheses. Bilateral laryngoplasties were performed on each of 15 (seven 2-year-old, two 3-year-old, and six 4-year-old) larynges, which were collected at an abbatoir. Prostheses were secured to a mechanical testing machine, and tension causing arytenoid cartilage abduction was applied, until total failure of the cartilage or prosthesis resulted. Tension caused cricoid cartilage failure in 1 specimen, and muscular pr...
McCluskie LK, Franklin SH, Lane JG, Tremaine WH, Allen KJ.To assess the effect of head position on relative position of the larynx and hyoid apparatus in horses with palatal dysfunction, and to define a standard position for radiographic assessment of laryngeal tie-forward. Methods: Prospective clinical study. Methods: Adult horses (n=9) with palatal dysfunction. Methods: Left lateral radiographs of the larynx were obtained pre and postoperatively for 3 different head positions (flexed=90 degrees ; neutral=100 degrees ; extended=115 degrees ). Distance between thyrohyoid bone and thyroid cartilage was measured. Data were analyzed to investigate diffe...
Holcombe SJ, Derksen FJ, Berney C, Becker AC, Horner NT.To determine the effect of desensitization of the laryngeal mucosal mechanoreceptors on upper airway mechanics in exercising horses. Methods: 6 Standardbreds. Methods: In study 1, videoendoscopic examinations were performed while horses ran on a treadmill with and without topical anesthesia of the laryngeal mucosa. In study 2, peak tracheal and nasopharyngeal pressures and airflows were obtained from horses during incremental treadmill exercise tests, with and without topical anesthesia of the laryngeal mucosa. A nasal occlusion test was performed on each horse while standing during an endosco...
Mair TS, Batten EH, Stokes CR, Bourne FJ.Mucosal lymphoid nodules were identified within the equine respiratory tract by an acetic acid fixation technique. Nodules were identified in foetuses from nine months gestational age, and estimates of total and regional nodule populations were made in foetal, neonatal and adult horses. Nodules occurred at specific sites within the tract, which probably relate to areas where inhaled antigens accumulate. The largest populations of nodules occurred in the nasopharynx and larynx, with smaller numbers in the nasal cavity, trachea and bronchi. There was an age-related change in the size of these no...
Davison JA, Lumsden JM, Boston RC, Ahern BJ.To review a large number of equine overground endoscopy (OGE) examinations to determine the incidence of dynamic upper airway obstructions (DUAO); correlations were explored with laryngeal endoscopy findings at rest and abnormal exercising respiratory noise. Methods: Retrospective analysis of horses presenting for OGE because of perceived poor performance and/or history of abnormal exercising respiratory noise between 2010 and 2014. Signalment, history and examination findings during resting laryngeal endoscopy and OGE were reviewed. Results: Of the total examinations, 311 were reviewed. One o...
Tetens J, Derksen FJ, Stick JA, Lloyd JW, Robinson NE.To evaluate the efficacy of prosthetic laryngoplasty with and without bilateral ventriculocordectomy for treatment of experimentally induced left laryngeal hemiplegia (LLH). Methods: 15 adult Standardbreds. Methods: Horses were allotted to 3 equal groups. Sham operation (group 1), prosthetic laryngoplasty (group 2), or prosthetic laryngoplasty with bilateral ventriculocordectomy (group 3) was performed after induction of LLH. Upper airway function testing was performed prior to left recurrent laryngeal neurectomy (LRLN), 14 days after LRLN, and 60 and 180 days after surgical treatment. Measure...
Duncan ID, Baker GJ, Heffron CJ, Griffiths IR.The larynges of 6 horses were examined endoscopically and the findings correlated with the gross and histological appearance of the intrinsic laryngeal muscles and their nerve supply. In all cases it appeared that the balance between abductor and adductor muscle groups had been lost due to preferential atrophy of individual muscles or groups of muscles. The laryngeal abnormalities recorded were asymmetry of the larynx with asynchronous left sided abduction and fluttering or trembling of the left vocal cord and arytenoid cartilage. It is suggested that these changes represent the early signs of...
