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Topic:Larynx
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.
Comparison of morphological changes and tactile sensitivity of the pharynx and larynx between four standing sedative and analgesic protocols in eight adult healthy horses. To compare the topographic modifications and tactile sensitivity of the pharynx and larynx after administration of four sedative and analgesic protocols in standing horses. Methods: Experimental, observer-blinded, crossover study. Methods: Eight healthy mares. Methods: Five protocols were evaluated: 1) xylazine and butorphanol administered intravenously (IV); 2) detomidine and butorphanol administered IV; 3) xylazine administered IV and lidocaine topically; 4) detomidine administered IV and lidocaine topically and 5) no analgesia or sedation (control). Quality of sedation, head height and sudd...
The occurrence of dynamic structural disorders in the pharynx and larynx, at rest and during exercise, in horses diagnosed with mild and moderate Equine Asthma (Inflammatory Airway Disease). The goal of the present study was to establish the occurrence of structural disorders in the larynx and pharynx during treadmill exercise tests in horses diagnosed with Equine Asthma (EA). Investigation was performed in 29 horses, patients of the Equine Clinic of the Warsaw University of Life Sciences in Poland, admitted with poor exercise performance. Upper and lower airway examinations were performed in all patients revealing both mild to moderate Equine Asthma (13 horses), and no lower airway abnormalities (16 animals). In the group of horses with EA, 11 did not have structural disorders of...
Modified first or second cervical nerve transplantation technique for the treatment of recurrent laryngeal neuropathy in horses. 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...
Hold your horses: A comparison of human laryngomalacia with analogous equine airway pathology. Laryngomalacia is the most common cause of stridor in infants. Dynamic airway collapse is also a well-recognised entity in horses and an important cause of surgical veterinary intervention. We compare the aetiology, clinical features and management of human laryngomalacia with equine dynamic airway collapse. Methods: A structured review of the PubMed, the Ovid Medline and the Cochrane Collaboration databases (Cochrane Central Register of Controlled Trials, Cochrane Database of Systemic Reviews). Results: There are numerous equine conditions that cause dynamic airway collapse defined specifical...
Overground endoscopy in 311 Thoroughbred racehorses: findings and correlation to resting laryngeal function. 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...
Evaluation of two methods for topical application of contrast medium to the pharyngeal and laryngeal region of horses. OBJECTIVE To determine the pharyngeal and laryngeal distribution of radiopaque contrast medium administered orally or via nasopharyngeal catheter to standing horses. ANIMALS 5 healthy adult horses. PROCEDURES A crossover study was conducted. Radiopaque contrast medium (12 mL) was administered orally and via nasopharyngeal catheter to each horse. Pharyngeal and laryngeal distribution of contrast medium was determined by examination of radiographs obtained immediately after administration of contrast medium, compared with those obtained before administration. Regional distribution of contrast me...
Ex vivo biomechanical stability of 5 cricoid-suture constructs for equine laryngoplasty. To determine the biomechanical properties of 5 suture constructs in the equine cricoid under cyclic loading and load to failure testing. Methods: Ex vivo study. Methods: Seventy-five equine cadaver larynges. Methods: Each larynx was implanted with 1 of 5 cricoid-suture constructs. The standard laryngoplasty, where a suture is passed once through the cricoid, including its caudal edge, was used in 2 constructs: 1 with 5 USP Ethibond (ES) and 1 with 2 mm Fibertape (FS). In the third construct, the 2 mm Fibertape was passed twice through the cricoid including its caudal edge (Double Loop-DL). Con...
In vitro comparison of 3 techniques of prosthesis attachment to the muscular process of the equine arytenoid cartilage. To determine the degree and ease of arytenoid abduction achieved with abaxial placement of a FASTak II suture anchor compared to 2 suture patterns with different directions of insertion-caudomedial to craniolateral and medial to lateral. Methods: Ex vivo experimental. Methods: Cadaveric larynges from 10 Standardbred racehorses. Methods: Each larynx was sequentially instrumented with all 3 arytenoid suture attachment in random order: (1) abaxial placement of a FASTak II suture, (2) caudomedial to craniolateral suture, and (3) medial to lateral suture placement. Each construct was abducted at 5N...
Modified technique for common carotid artery transposition in standing horses. To describe a modified technique for permanent translocation of the common carotid artery (CCA) to a subcutaneous position in standing horses. Methods: Experimental study. Methods: Healthy adult Standardbred and Warmblood horses (n = 8). Methods: Surgery was performed with the horses standing under sedation and with local anesthesia. A combination of previously described techniques was used modifying the approach and closure of the incision. The right CCA was approached through a linear skin incision dorsal and parallel to the jugular vein and through the brachiocephalicus and omohyoideus ...
Oesophageal lumen pH in yearling horses and effects of management and administration of omeprazole. In human subjects, arytenoid chondritis can be caused by chemical trauma of mucosa attributable to gastro-oesophageal reflux. Although a similar process may be involved in the aetiopathogenesis of arytenoid chondritis in horses, the oesophageal lumen pH in this species is poorly understood. Objective: To determine if gastro-oesophageal reflux occurs in horses by characterising oesophageal lumen pH. Methods: Blinded, randomised, placebo-controlled, crossover, experimental study. Methods: Luminal oesophageal pH in six yearling horses was recorded over four 24 h periods using an ambulatory pH rec...
IMAGING DIAGNOSIS-IDIOPATHIC HYOID MALFORMATION IN AN 8-YEAR-OLD WELSH SECTION D HORSE. An 8-year-old gelding was evaluated for intermittent dorsal displacement of the soft palate (DDSP) at exercise. Standing laterolateral radiographs demonstrated an abnormal crossed appearance of the stylohyoid bones. Computed tomography (CT) confirmed abnormal positioning of the left stylohyoid bone and articulations with both the left thyrohyoid and ceratohyoid bones. Surgical treatment consisted of combined left ceratohyoidectomy and thyrohyoidectomy. Postoperatively the patient's presenting complaint resolved completely, with the horse returning to full work. Standing laterolateral radiograp...
Surgical Treatment of Iatrogenic Ventral Glottic Stenosis Using a Mucosal Flap Technique. To describe a novel surgical technique for correcting postoperative ventral glottic stenosis (cicatrix or web formation) and the outcome in 2 Thoroughbred racehorses. Methods: Retrospective case report. Methods: Thoroughbreds diagnosed with ventral glottic stenosis (n=2). Methods: Horses presenting with iatrogenic ventral glottic stenosis and resultant exercise intolerance and abnormal exercise-related noise were anesthetized and a midline sagittal skin incision was made over the ventral larynx and between the sternohyoideus muscles overlying the cricothyroid notch. The cricothyroid ligament, ...
Ex Vivo Mechanical Evaluation of a Sternal ZipFix(®) Implant for Prosthetic Laryngoplasty in Horses. To evaluate the properties of a ZipFix(®) (ZipFix) implant in equine laryngeal cartilages. Methods: Ex vivo biomechanical study. Methods: Equine arytenoid (n=36) and cricoid cartilages (n=18). Methods: Suture bites were placed in arytenoid or cricoid cartilages using a ZipFix(®) implant or a single strand of USP 5 braided polyester (TiCron™), and arytenoid and cricoid cartilages were separately subjected to single load to failure (25 N preload) or cyclic loading for 1,000 cycles, followed by single load to failure. Load, distraction, and stiffness were recorded. Results: Four arytenoid-Zip...
Transoesophageal ultrasound and computer tomographic assessment of the equine cricoarytenoid dorsalis muscle: Relationship between muscle geometry and exercising laryngeal function. Early detection of recurrent laryngeal neuropathy (RLN) is of considerable interest to the equine industry. Objective: To describe two imaging modalities, transoesophageal ultrasound (TEU) and computed tomography (CT) with multiplanar reconstruction to assess laryngeal muscle geometry, and determine the relationship between cricoarytenoid dorsalis (CAD) geometry and function. Methods: Two-phase study evaluating CAD geometry in experimental horses and horses with naturally occurring RLN. Methods: Equine CAD muscle volume was determined from CT scan sets using volumetric reconstruction with Live...
COMPUTED TOMOGRAPHIC APPEARANCE OF MELANOMAS IN THE EQUINE HEAD: 13 CASES. 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...
Training of upper respiratory endoscopy in the horse using preserved head and neck. Endoscopy of the upper respiratory tract (URT) is one of the minimally invasive techniques used for diagnosis and treatment of diseases in horses. Training in the use of an endoscope follows an apprenticeship approach, with extensive practice needed to help achieve effective skills acquisition. The use of live animals for training presents the risk of injury to both the animal and the trainee. The increased number of students and practitioners, a shortage of facilities, and limited time available from expert clinicians add more challenges to the training process. In this work, we focused on th...
Laryngeal advancement surgery improves swallowing function in a reversible equine dysphagia model. Pharyngeal dysphagia is a debilitating, sometimes fatal condition in horses, with multiple aetiologies. The pathophysiology is complex and not fully understood. Treatment is largely supportive. Laryngeal advancement surgery may diminish symptoms of dysphagia and improve swallowing in affected horses. Objective: 1) to induce reversible moderate and marked pharyngeal dysphagia by regional anaesthesia of branches of the glossopharyngeal (IX), vagus (X) and hypoglossal (XII) nerves; 2) to characterise the dysphagia produced by each model; and 3) to determine whether laryngeal advancement surgery i...
Ultrasonographic detection of early atrophy of the intrinsic laryngeal muscles of horses. To describe the ultrasonographic changes in the cricoarytenoideus dorsalis (CAD) and cricoarytenoideus lateralis (CAL) muscles of horses before and at various times during the 32 weeks after unilateral neurectomy of the right recurrent laryngeal nerve. Methods: 28 healthy Standardbreds. Methods: For each horse, the appearance of the CAD and CAL muscles on the right (neurectomized) and left (control) sides was serially monitored ultrasonographically by percutaneous (CAD and CAL) and transesophageal (CAD) approaches. The ultrasonographic images were assessed to determine the mean pixel intensity...
In vitro mechanical evaluation of equine laryngeal tie-forward constructs prepared with different suture materials and placement patterns. To compare the mechanical properties of laryngeal tie-forward (LTF) constructs prepared with different suture materials and suture placement patterns during single load to failure testing. Methods: Larynges harvested from 50 horse cadavers and 5 intact horse cadavers. Methods: In vitro LTF constructs were created by a standard technique with polyester sutures, a standard technique with polyethylene sutures, a modified technique with metallic implants and polyester sutures, a modified technique with metallic implants and polyethylene sutures, or a modified tie-off technique with polyester sutur...
Update on laryngeal disorders and treatment. Laryngeal disorders are relatively common in the horse, and thorough diagnostic evaluation is essential to make an accurate definitive diagnosis and selection of appropriate treatment. The value of exercising endoscopy must not be overlooked, and the recent development of dynamic (overground) endoscopy is providing new insights into dynamic laryngeal lesions. The focus of this article will be on recently described disorders and treatments or modifications to existing treatments. It summarizes the numerous investigations attempting to perfect the laryngoplasty procedure for treatment of larynge...
Dynamic upper respiratory abnormalities in Thoroughbred racehorses in South Africa. Upper airway endoscopy at rest has been the diagnostic method of choice for equine upper respiratory tract (URT) conditions. Development of high-speed treadmill endoscopy improved the sensitivity of URT endoscopy by allowing observation of the horse's nasopharynx and larynx during exercise. However, treadmill exercise may not always accurately represent the horse's normal exercise as track surface, rider, tack and environmental variables are altered. Recently, the development of dynamic overground endoscopy (DOE) has addressed some of these shortcomings. A retrospective study was undertaken to...
Endoscopic, transoral, reduction of epiglottic entrapment via wire snare technique. To describe the use of a wire snare technique for epiglottic entrapment. Methods: Case series. Methods: Eight adult horses. Methods: Under general anesthesia, a modified mouth gag was placed in the oropharynx. An endoscope was passed through the gag until there was adequate visualization of the entrapped epiglottis. The entrapping mucosa was grasped with bronchoesophageal forceps and pulled rostrally, releasing the epiglottis. A custom snare was passed down the bronchoesophageal forceps to encircle the redundant subepiglottic mucosa. Tension was applied to the entrapping mucosa via the forceps...
[Complex fracture of the larynx caused by a horse kick]. Every blunt laryngeal trauma requires examination by an ENT physician and may necessitate observation for a number of hours. The literature shows a heterogeneous picture regarding airway management (tracheotomy vs. intubation). Extremely violence forces such as horse kicks require a tracheotomy, as demonstrated by case studies. In such cases, a high level of responsibility lies with the emergency physician providing the initial treatment. We present the case of a 37-year-old horse trainer, who suffered a horse kick to the larynx with a complex laryngeal fracture. Intubation of the patient by t...
Tracheal resection and anastomosis after traumatic tracheal stenosis in a horse. To report a resection and anastomosis technique to treat trauma-induced tracheal stenosis. Methods: Case report. Methods: A 9-year-old Warmblood gelding. Methods: Endoscopy, radiography, and ultrasonography were used to diagnose a single ring tracheal stenosis; the stenotic region was resected and adjacent tracheal rings anastomosed with an end-to-end technique. Results: The anastomosis healed completely despite formation of a unilateral partial mucosal stenosis "web," which was subsequently removed by transendoscopic laser surgery. During tracheal anastomosis, the left recurrent laryngeal ner...
The effect of the laryngeal tie-forward procedure and soft palate cautery on nasopharyngeal diameter in horses. The laryngeal tie-forward (LTF) procedure has been shown to move the larynx rostrally and dorsally whilst repositioning the basihyoid bone caudally and dorsally. Other studies have shown that the position of the hyoid bones influences the size of the nasopharynx. The effect of the LTF procedure on the size of the nasopharynx is unknown. It was hypothesised that the LTF procedure would result in a decrease in dorsoventral nasopharyngeal diameter. Twenty-five thoroughbred horses which underwent LTF with or without soft palate cautery (LTF±SPC) for treatment of dorsal displacement of the soft pa...
Diagnosis and treatment of dynamic collapse of the cricotracheal ligament in thoroughbred racehorses. To describe (1) diagnosis of dynamic collapse of the cricotracheal ligament in a group of horses and (2) treatment and outcome of affected horses. Methods: Retrospective case series. Methods: Thoroughbred horses (n = 8). Methods: Of 600 over ground dynamic endoscopic examinations performed, 8 Thoroughbred horses had cricotracheal ligament collapse (CTLC); 5 were 2 years old and in early training and 2 were mature horses in full work. CTLC was diagnosed if circumferential collapse of the cricotracheal ligament was identified during exercise. Seven horses had repeat endoscopic examination. T...
Mechanical comparison of 3 anchoring techniques in the muscular process for laryngoplasty in the equine larynx. 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...
In vitro mechanical testing of braided polyurethane elastic fiber and braided polyester for equine laryngoplasty. In vitro comparison of the mechanical properties of braided polyurethane elastomer (Lycra®) and braided polyester (Ethibond™) (1) when inserted into the muscular process of the arytenoid cartilage and (2) as suture loops. Methods: Experimental. Methods: Equine cadaver larynges (n = 15). Methods: The muscular processes (n = 30) of the arytenoid cartilages were dissected from each larynx and embedded in a resin base. Lycra® and Ethibond™ prostheses were randomly allocated to the left or right muscular process and each underwent cyclic fatigue (25-50 N) followed by load-to-failure...
Genetics of upper and lower airway diseases in the horse. Genetic predispositions for guttural pouch tympany, recurrent laryngeal neuropathy and recurrent airway obstruction (RAO) are well documented. There is also evidence that exercise-induced pulmonary haemorrhage and infectious diseases of the respiratory tract in horses have a genetic component. The clinical expression of equine respiratory diseases with a genetic basis results from complex interactions between the environment and the genetic make-up of each individual horse. The genetic effects are likely to be due to variations in several genes, i.e. they are polygenic. It is therefore unlikel...
