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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.
Mechanical properties of various suture materials and placement patterns tested with surrogate in vitro model constructs simulating laryngeal advancement tie-forward procedures in horses. To compare the mechanical properties of laryngeal tie-forward (LTF) surrogate constructs prepared with steel fixtures and No. 5 braided polyester or braided polyethylene by use of a standard or a modified suture placement technique. Methods: 32 LTF surrogate constructs. Methods: Surrogate constructs were prepared with steel fixtures and sutures (polyester or polyethylene) by use of a standard or modified suture placement technique. Constructs underwent single-load-to-failure testing. Maximal load at failure, elongation at failure, stiffness, and suture breakage sites were compared among constr...
An ex vivo model to evaluate the effect of cyclical adductory forces on maintenance of arytenoid abduction after prosthetic laryngoplasty performed with and without mechanical arytenoid abduction. To (1) develop a model of cyclical adduction force on an abducted left arytenoid cartilage that mimics swallowing or coughing; (2) determine if arytenoid abduction by a clamp before knot tying will improve the maintenance of abduction under cyclical adduction testing. Methods: Experimental. Methods: Cadaveric equine larynges (n = 14). Methods: Left laryngoplasty performed using a single suture of #5 Ethibond with (n = 7) and without (n = 7) abducting the arytenoid with a clamp before knot tying. Each laryngoplasty was loaded cyclically from 2 to 26 N at 0.5 Hz for 5000 cycles i...
Regenerative medicine approach to reconstruction of the equine upper airway. Airway obstruction is a common cause of poor performance in horses. Structural abnormalities (insufficient length, rigidity) can be a cause for the obstruction. Currently, there are a few effective clinical options for reconstruction of the equine larynx. A regenerative medicine approach to reconstruction may provide the capability to stabilize laryngeal structures and to encourage restoration of site-appropriate, functional, and host-derived tissue. The purpose of this study was the histopathological evaluation of (1) decellularization of equine (horse) laryngeal cartilages (epiglottis and ar...
Standing equine surgery of the upper respiratory tract. The purpose of this article is to review the literature and personal experiences of equine surgeons so as to describe procedures that can be performed in the standing sedated horse to alleviate conditions that result in upper respiratory tract obstruction. Upper respiratory tract surgery requires attention to detail, meticulous planning, and careful dissection and execution with little room for error. This article describes a selection of standing upper airway procedures, the indications for and possible complications of these surgeries, and advantages and disadvantages of a particular method....
Effects of different head-neck positions on the larynges of ridden horses. 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 ...
Computed tomography-guided tissue engineering of upper airway cartilage. Normal laryngeal function has a large impact on quality of life, and dysfunction can be life threatening. In general, airway obstructions arise from a reduction in neuromuscular function or a decrease in mechanical stiffness of the structures of the upper airway. These reductions decrease the ability of the airway to resist inspiratory or expiratory pressures, causing laryngeal collapse. We propose to restore airway patency through methods that replace damaged tissue and improve the stiffness of airway structures. A number of recent studies have utilized image-guided approaches to create cell-...
Results of upper airway radiography and ultrasonography predict dynamic laryngeal collapse in affected horses. The pathogenesis of dynamic bilateral laryngeal collapse (DLC) associated with poll flexion is unknown. Diagnosis is dependent upon exercise endoscopy while replicating the flexed head position harness racehorses experience during racing. Objective: To describe the effects of poll flexion on rostrocaudal laryngeal positioning and laryngeal lumen width in resting horses diagnosed with DLC compared to controls, and to establish diagnostic criteria for DLC by use of diagnostic imaging. Methods: Case-control study. Methods: Fifty harness racehorses were prospectively included in the study: 25 case...
Effects of hypoglossal nerve block and electrical stimulation of the thyrohyoideus muscles on position of the larynx and hyoid apparatus in healthy horses. To determine the effects of hypoglossal nerve block and electrical stimulation of the thyrohyoideus muscles on position of the larynx and hyoid apparatus in resting horses. Methods: 16 healthy horses that underwent hypoglossal nerve block and 5 healthy horses that underwent electrical stimulation of the thyrohyoideus muscles. Methods: Horses underwent bilateral hypoglossal nerve block or electrical stimulation of the thyrohyoideus muscles. Positions of the basihyoid bone, ossified part of the thyroid cartilage, and articulations of the thyrohyoid bones and thyroid cartilage were determined in ...
The use of a tongue tie alters laryngohyoid position in the standing horse. The use of tongue ties in racing is common, yet there are few data to support their efficacy. In order to make appropriate recommendations for clinical practice and policy on tongue ties, data documenting their effect on upper airway structure are necessary. Objective: To determine the effect of a tongue tie on the resting laryngohyoid position of the standing horse. Methods: Experimental study. Methods: Twelve normal Standardbred horses were subjected to ultrasonographic measures of laryngohyoid position during 3 phases of tack application: Phase I--halter and lead; Phase II--bit, bridle, har...
Long-term maintenance of arytenoid cartilage abduction and stability during exercise after laryngoplasty in 33 horses. To (1) assess long-term maintenance of arytenoid cartilage abduction (ACA) after laryngoplasty (LP); and (2) correlate the residual grade of ACA and postoperative abductory loss with arytenoid cartilage stability (ACS) during exercise. Methods: Case series. Methods: Horses re-examined after laryngoplasty (n = 33). Methods: Of 89 LP horses (2005-2010), 33 had historic ACA data available and upper airway endoscopy at rest and during over-ground exercise (mean, 33 months; range, 4-71 months) after surgery. ACA grade at 1 and 6 weeks postoperatively were correlated to long-term ACA grade. Effects ...
Effect of age and prostheses location on rima glottidis area in equine cadaveric larynges. To determine the effect of horse age and laryngeal prosthesis location on rima glottidis area in cadaveric larynges. Methods: Experimental study. Methods: Cadaveric equine larynges (n = 40). Methods: Specimens were grouped by age: group 1, ≤5 years (n = 18); group 2, >5 to ≤10 years (n = 12); group 3, >10 years (n = 10). A cranial prosthesis was placed through the dorsal cricoid spine at 70% of the distance of the total cricoid length measured from the caudal rim. A dorsal prosthesis was placed through the caudal rim of the cricoid on the dorsal midline. A lateral prosthesis was plac...
Ultrasound features of arytenoid chondritis in Thoroughbred horses. Laryngeal ultrasonography can provide valuable information when considering a diagnosis of arytenoid chondritis, but specific ultrasonographic parameters have not been defined. Objective: To compare ultrasonographic findings of the arytenoid cartilages in horses with endoscopically diagnosed arytenoid chondritis with ultrasonographic findings of the arytenoid cartilages in normal horses. Methods: Ultrasound images of the larynx were obtained at the level of the arytenoid cartilages in horses with endoscopically diagnosed arytenoid chondritis and horses with normal arytenoid cartilage structure...
Optimal tension, position, and number of prostheses required for maximum rima glottidis area after laryngoplasty. To evaluate the effect of 3 laryngeal prostheses alone or in combination on rima glottidis area in horses. Methods: Experimental randomized design. Methods: Cadaveric equine larynges (n = 22). Methods: Three prostheses were preplaced in each of 14 larynges. Rima glottidis area was measured after loading each suture in 5 Newton (N) increments from 0 N to 35 N. In 8 larynges, the 3 prostheses were tied alone or in combination at a fixed load of 15 N and rima glottidis area measured. Results: Rima glottidis cross-sectional area increased as the load on each prosthesis increased with maximum area ...
Characteristics of palatal instability in Thoroughbred racehorses and their association with the development of dorsal displacement of the soft palate. Two forms of dynamic upper respiratory tract obstruction affecting racehorses that involve the soft palate have been described: palatal instability (PI) and dorsal displacement of the soft palate (DDSP). Observation of DDSP is straightforward in that it is an all or nothing event, whereas observation of PI is subjective and interpretation may vary between clinicians. Objective: The aim of this study was to attempt to characterise PI and to investigate endoscopic features that precede DDSP. Methods: A retrospective study on the endoscopic observations of Thoroughbred racehorses referred for hig...
Diagnostic sensitivity of subjective and quantitative laryngeal ultrasonography for recurrent laryngeal neuropathy in horses. Recurrent laryngeal neuropathy (RLN) is the most common cause of laryngeal hemiplegia in horses and causes neurogenic atrophy of the intrinsic laryngeal muscles, including the cricoarytenoideus lateralis muscle. Recurrent laryngeal neuropathy results in paresis to paralysis of the vocal fold and arytenoid cartilage, which limits performance through respiratory compromise. Ultrasound has previously been reported to be a useful diagnostic technique in horses with RLN. In this report, the diagnostic sensitivity of subjective and quantitative laryngeal ultrasonography was evaluated in 154 horses p...
[‘Laryngeal neuropathy’ and ‘irritable larynx syndrome’: synonyms or distinct entities?]. The term 'laryngeal neuropathy' (LN) has first been used in veterinary medicine to describe an idiopathic and typically exercise induced inspiratory noise in horses.Nowadays, the term is often used in relation with intermittent vocal cord pareses in humans. Some authors use the term 'irritable larynx syndrome' (ILS) in a similar context. This article reviews the state of knowledge regarding LN and ILS and discusses the somewhat confusing terminology.For this systematic review a selective literature research in PubMed has been carried out.35 articles were found, which report on LN in animals an...
Equine laryngeal rhinosporidiosis in western Canada. A 12-year-old female Argentinean Warmblood mare was evaluated because of respiratory noise. The horse resided in Calgary, Alberta, Canada, but had been imported from Argentina 28 months prior to presentation. Endoscopy of the upper respiratory tract revealed a single polypoid mass on the left arytenoid. The mass was surgically excised and was diagnosed histologically as rhinosporidiosis. Polymerase chain reaction and DNA sequencing were used to confirm the etiological agent. Four weeks postoperatively, endoscopy was repeated, revealing recurrence of the original lesion with multiple additional...
Evaluation of a laryngotomy approach for near-total resection of the nasal septum in the horse. To report a laryngotomy approach for the removal of the nasal septum in adult horses. Methods: Descriptive study. Methods: Horses (n = 10). Methods: Near-total resection of the nasal septum was made using a modification of a previously reported 3-wire technique using a trephination approach and a 2-wire technique using a laryngotomy approach. Surgical time, ease of technique, complications, and outcome were recorded. At 45 days, horses were euthanatized and septal measurements made. Results: Near-total resection of the nasal septum was accomplished with both techniques without complications. I...
Dynamic respiratory endoscopy of Standardbred racehorses during qualifying races. Examination of the equine upper airway during racing has not previously been documented. Objective: To describe the feasibility and appearance of the upper airways by overground respiratory endoscopic examination during racing conditions. Methods: Overground videoendoscopic examinations were performed on 46 Standardbred racehorses during qualifying races. Examined horses' speeds were recorded throughout the race with a portable GPS device. Results: The procedure did not interfere with performance as there were no significant differences in race times between races in which horses were examined...
Association of clinical signs with endoscopic findings in horses with nasopharyngeal cicatrix syndrome: 118 cases (2003-2008). To characterize the associations between clinical signs of nasopharyngeal cicatrix syndrome (NCS) and endoscopic findings in horses. Methods: Retrospective, case-control study. Methods: 239 horses (118 case horses and 121 control horses). Methods: Medical records of horses that had an endoscopic evaluation of the upper airway performed between January 2003 and December 2008 were reviewed. Clinical signs and the appearance and anatomic locations of lesions identified during endoscopic evaluation were reviewed and recorded for each horse. The associations between clinical signs and endoscopic fi...
Complex dynamic upper airway collapse: associations between abnormalities in 99 harness racehorses with one or more dynamic disorders. 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...
Dynamic respiratory videoendoscopy in ridden sport horses: effect of head flexion, riding and airway inflammation in 129 cases. Dynamic upper airway obstruction (UAO) is a cause of respiratory noise and sometimes poor performance in sport horses. Riding, head flexion and airway inflammation may impact upper respiratory tract stability during exercise. Objective: To evaluate upper airway mechanical behaviour in ridden sport horses using overground endoscopy and the effect of head flexion, rider intervention and underlying airway inflammation on the pharynx and larynx. Methods: Resting and exercising videoendoscopic recordings during ridden exercise were obtained in 129 sport horses referred mainly for respiratory noise,...
Functional electrical stimulation of intrinsic laryngeal muscles under varying loads in exercising horses. Bilateral vocal fold paralysis (BVCP) is a life threatening condition and appears to be a good candidate for therapy using functional electrical stimulation (FES). Developing a working FES system has been technically difficult due to the inaccessible location and small size of the sole arytenoid abductor, the posterior cricoarytenoid (PCA) muscle. A naturally-occurring disease in horses shares many functional and etiological features with BVCP. In this study, the feasibility of FES for equine vocal fold paralysis was explored by testing arytenoid abduction evoked by electrical stimulation of t...
Pulmonary edema at recovery after colic operation with in-situ nasogastric tube in a horse. After an uneventful general anesthesia, in a horse negative pressure pulmonary edema developed due to acute upper airway obstruction during the anesthetic recovery phase after colic surgery. No pathologic alteration of respiration was observed until the horse stood up and began suffocating. The horse had recovered with the nasogastric tube in situ. This, together with the postmortem diagnosis of laryngeal hemiplegia resulted in impairment of airflow through the larynx and development of pulmonary edema. Our objective is to alert clinicians about the possible hazard of recovery with an in-situ ...
Epiglottic abnormalities in mature nonracehorses: 23 cases (1990-2009). To identify history, clinical signs, endoscopic findings, treatment, and outcome of mature (> 8 years old) nonracehorses with epiglottic abnormalities. Methods: Retrospective case series. Methods: 23 horses with an epiglottic abnormality. Methods: Medical records of horses examined between 1990 and 2009 because of an epiglottic abnormality were reviewed to obtain information on signalment, history, clinical signs, clinical examination findings, upper airway endoscopic findings, diagnosis, surgical procedure, clinical management, postoperative care, and outcome. Results: Mean ± SD age was 16 Â...
Analysis of conformational variations of the cricoid cartilages in Thoroughbred horses using computed tomography. Loss of arytenoid abduction is a common post operative complication of laryngoplasty without a definitive cause. It has been a clinical impression during laryngoplasty surgery that there is great conformational variability along the caudal edge of the Thoroughbred cricoid cartilage that could impact post operative retention of suture position. A change in suture position would probably lead to some loss of abduction. Defining any structural variability of the cricoid would be an initial step in determining whether this variability could impact on the retention of suture position. Objective: An...
Biomechanical characterisation of equine laryngeal cartilage. 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...
