Upper Airway Obstruction: What the Research Says
Evidence from 25 peer-reviewed studies
What Professionals Should Know
- •Modified laryngoplasty with cricoarytenoid joint ankylosis provides superior long-term maintenance of arytenoid abduction compared to standard laryngoplasty, reducing the need for revision surgery in horses with laryngeal hemiplegia
- •The procedure achieves mechanical stability through joint fusion rather than relying on suture tension alone, offering more durable results for performance horses
- •Consider this modified approach for horses requiring laryngoplasty, particularly those with high performance demands where loss of abduction would be career-limiting
- •Do not use laser vocal cordectomy as a treatment for roaring in laryngeal hemiplegia cases, as it fails to reduce respiratory noise despite some pressure reduction
- •Bilateral ventriculocordectomy remains a more effective surgical option if noise reduction is the clinical goal in affected horses
- •Understand that reducing upper airway pressure alone does not translate to clinically meaningful noise reduction in this condition
- •Investigate and manage lower airway inflammation in underperforming trotters, as it has both immediate and career-long impacts on racing success.
- •Upper airway problems and gastric ulcers may temporarily limit racing but don't necessarily predict permanent career damage if managed appropriately.
- •The role of exercise-induced pulmonary hemorrhage and cardiac arrhythmias in poor performance remains uncertain; assess these findings alongside other clinical signs rather than assuming causation.
- •Cardiac arrhythmias are very common in poorly performing trotters (77-78%) but do not appear to be causally related to upper airway obstruction, suggesting other etiologies should be investigated
- •Recovery period arrhythmias (particularly in the first 2 minutes) may be more clinically significant than exercise-induced arrhythmias; monitor peak exercise heart rate as a potential predictor
- •Standard categorization of arrhythmias as supraventricular versus ventricular may be unreliable in horses; descriptive reporting of arrhythmia characteristics is more useful clinically
- •Monitor blood gas values during exercise testing as elevated CO2 and lactate are objective markers predicting higher-risk arrhythmias in poor-performing horses
- •Upper airway obstruction status alone does not predict exercise arrhythmias; metabolic changes (hypercapnia/hyperlactatemia) are the key risk factors to assess
- •Consider exercise intolerance and poor performance in conjunction with arterial blood gas analysis rather than relying solely on respiratory disease diagnosis
- •VCE is the recommended surgical approach for treating RLN in draught horses due to superior reduction in airway noise compared to VE alone
- •Expect realistic success rates around 83% owner satisfaction with VCE, but allow adequate recovery time (120 days total) before returning horses to competitive pulling
- •Both procedures are safe options with minimal complications, but VCE produces significantly better functional outcomes for draught horse performance
- •Laser fenestration of the dorsal pharyngeal recess should not be considered an effective treatment for dorsal nasopharyngeal collapse in horses based on this experimental evidence
- •Alternative surgical or medical approaches to managing NPC should be explored, as this procedure does not restore respiratory performance metrics
- •Clinicians should be cautious about applying this technique until further evidence supports its efficacy, particularly since endoscopic appearance may not correlate with functional improvement
- •Unilateral cervical swelling present from birth warrants diagnostic imaging to rule out congenital tracheal lesions; ultrasound and endoscopy can identify these defects effectively.
- •Contrast CT provides essential surgical planning information by delineating the exact anatomical origin and course of the diverticulum relative to tracheal rings.
- •Complete surgical excision offers excellent prognosis in foals with congenital tracheal diverticula, supporting early intervention when diagnosis is confirmed.
- •Bilateral laryngeal paralysis can emerge as a late post-anesthetic complication; maintain high suspicion for underlying systemic neurological disease if paralysis develops after routine recovery
- •Upper airway obstruction in recovering anesthetized horses requires immediate emergency tracheostomy; have equipment and personnel prepared for rapid airway intervention
- •Consider infectious or protozoal causes (EPM, neuroborreliosis) in horses presenting with combined laryngeal dysfunction and neurological signs, as these may respond to specific antimicrobial therapy
- •When harness racehorses continue to show respiratory signs after laryngeal tie-forward surgery, evaluate them specifically under working conditions (with bit/reins) rather than free lunging, as DLC may only manifest with poll flexion
- •Understand that normal appearance at rest or in free head carriage does not rule out post-surgical dynamic laryngeal collapse in these horses
- •Consider poll flexion mechanics as a risk factor when counselling clients on complications and expected outcomes of laryngeal tie-forward procedures
- •Suspect fungal rhinitis/sinusitis in Florida horses presenting with upper airway obstruction and nasal discharge; zygomycosis and phaeohyphomycosis are the most likely culprits requiring histopathology for diagnosis
- •Morphologic assessment combined with PCR/DNA sequencing provides the most reliable identification of fungal pathogens, particularly for phaeohyphomycosis cases
- •Be aware that multiple fungal species beyond common pathogens can cause rhinitis/sinusitis in subtropical/tropical climates, necessitating thorough diagnostic investigation
- •Pharyngeal sarcomas should be considered in differential diagnoses for upper airway obstruction and abnormal respiratory signs in horses
- •Multimodal diagnostic approach (physical exam, radiography, ultrasonography, endoscopy) improves diagnostic yield for pharyngeal lesions
- •Early recognition of chronicity and poor prognosis helps inform realistic client discussions about treatment limitations and humane endpoints
- •Younger horses with CTLC may improve with conservative management addressing underlying airway inflammation rather than requiring immediate surgery
- •Mature horses with persistent CTLC unresponsive to conservative treatment are candidates for surgical imbrication of the cricotracheal ligament
- •Dynamic endoscopy during exercise is required to diagnose CTLC, as static examination will miss this condition
- •Consider modified checkrein as an alternative management strategy for Coldblooded trotters with poll flexion-induced laryngeal collapse when conventional treatments fail to restore racing performance
- •Recognize that rein tension and poll flexion are direct mechanical triggers of airway obstruction in affected horses—management modifications may complement other interventions
- •This technique may offer a functional solution for performance horses where surgery has not improved outcomes
- •If a horse has no visible arytenoid abduction at rest after laryngoplasty, expect dynamic collapse during exercise; however, grade 3-4 resting abduction does not guarantee normal upper airway function during work.
- •Exercise endoscopy is necessary to fully assess post-laryngoplasty patients with ongoing poor performance, as resting exams miss critical dynamic obstructions involving multiple structures.
- •Respiratory noise alone cannot diagnose the cause of upper airway dysfunction—look for concurrent vocal fold billowing, soft palate displacement, and pharyngeal involvement to explain poor performance.
- •Include branchial apparatus anomalies in your differential diagnosis for any fluctuating mass in the throatlatch region of neonatal foals, particularly if the mass changes size with feeding.
- •Early surgical intervention with complete excision of the branchial tissue and tract ligation is recommended and offers excellent functional and cosmetic outcomes without need for additional mandibular correction.
- •Do not assume associated mandibular deformities are permanent; conservative management in young foals may result in complete spontaneous resolution following BAA removal.
- •Understanding normal soft palate anatomy is essential baseline knowledge for recognizing structural abnormalities that may predispose to dorsal displacement in racehorses
- •The dorsal location of muscle attachments and variable tissue composition between individual horses suggests anatomical variation may contribute to airway obstruction susceptibility
- •Knowledge of normal histological structure provides a reference standard for identifying pathological changes in horses presenting with upper airway obstruction
- •NPC should be considered in performance horses presenting with poor athletic performance or exercise intolerance, as it affects a significant proportion of high-performance athletes
- •Currently there is no effective treatment available, so focus should be on early recognition and realistic career counseling with owners regarding prognosis and likely retirement from competitive use
- •Further research is critically needed to develop therapeutic interventions that could extend athletic careers and reduce economic losses in affected horses
- •CFD modeling offers a non-destructive method to predict outcomes of upper airway procedures before performing them clinically, potentially improving surgical planning
- •This technology could help identify which procedural combinations work best for individual horses with airway obstruction, reducing trial-and-error approaches
- •Cadaveric validation supports future clinical application of computational modeling to optimize laryngeal surgeries and improve post-operative breathing outcomes
- •Consider bitless bridles as a potential welfare improvement, particularly for horses showing signs of respiratory compromise or bit aversion during exercise
- •Be aware that tight rein tension reducing jowl angle during ridden work can impair airflow and exacerbate respiratory distress in strenuous exercise
- •Assess horses for behavioural signs of bit-related discomfort and respiratory aversion, as these indicate potential pathophysiological effects on breathing capacity and welfare
- •Racing endoscopy is a diagnostic tool that does not interfere with horse performance and can identify airway obstructions that may not be apparent during standard training or treadmill examinations
- •Post-race airway collapse (DDSP) may be clinically relevant and worth monitoring, particularly in horses showing decreased race speed
- •VMAD during exercise appears more common than previously recognized in racing Standardbreds and should be considered in differential diagnoses for poor racing performance
- •The relatively straight geometry and high stiffness of equine cricoid cartilage means the larynx is mechanically robust; understanding these properties helps explain why soft tissue collapse causes obstruction rather than cartilage deformation
- •Age-related increases in cartilage stiffness may influence laryngeal function and response to surgical interventions in older horses
- •These biomechanical baseline values provide reference data for assessing laryngeal disease and optimizing surgical techniques like prosthetic laryngoplasty
- •This in vitro model enables systematic testing and optimization of laryngoplasty implants and suture techniques before clinical application, reducing need for trial-and-error in surgery
- •The validated pressure and flow data provide objective benchmarks for evaluating whether new prosthetic designs actually improve airway function during maximal exercise conditions
- •Surgeons can use findings to understand which suture materials and abduction angles best maintain upper airway patency under the high-demand conditions horses experience at speed
- •DDSP in racehorses may result from aerodynamic instability in the soft palate region during high-speed exercise rather than simple mechanical failure, suggesting treatment approaches should consider dynamic airway mechanics
- •The 7% larger cross-sectional area of the glottis compared to trachea indicates that maximal laryngeal opening may not be required for optimal performance, relevant when evaluating laryngeal function and surgical interventions
- •Understanding collapsible pressure zones in the upper airway helps target diagnostic imaging and endoscopic examination to high-risk regions during exercise simulation
- •When performing laryngoplasty for laryngeal hemiplegia, aim for maximal arytenoid abduction rather than partial abduction to prevent airway collapse during high-intensity exercise
- •Partial abduction (88% of maximal area) may represent an acceptable surgical compromise, but anything less risks compromising airway patency in working racehorses
- •Even modest reductions in arytenoid abduction force the horse's respiratory system to work harder during exercise, reducing efficiency and performance
Key Research Findings
Modified laryngoplasty resulted in fibrous ankylosis of the cricoarytenoid joint, confirmed histologically in all treated horses
Loss of arytenoid abduction at 3 months was significantly greater in control laryngoplasty (n=3) versus modified procedure (n=5)
Translaryngeal impedance was significantly lower in the modified laryngoplasty group compared to control, indicating better airway patency
Intact sutures maintained lower impedance compared to cut sutures, demonstrating the stabilizing effect of the surgical modification
Laser vocal cordectomy failed to reduce sound level or formant 1 and 3 intensity in horses with laryngeal hemiplegia during maximal exercise
The procedure reduced upper airway pressure and formant 2 intensity but these remained significantly elevated compared to baseline
Unilateral laser cordectomy provided equivalent obstruction relief to bilateral ventriculocordectomy but without noise reduction benefits
Airway neutrophilia was associated with reduced lifetime starts and wins both before and after hospitalization, showing sustained long-term impact on racing performance.
Mastocytosis was associated with fewer wins in the post-hospitalization period.
Upper airway obstruction and gastric ulcers reduced placings post-discharge but showed no long-term effects on career performance.
Exertional rhabdomyolysis reduced starts post-discharge and was associated with lower total career earnings, while exercise-induced pulmonary hemorrhage and cardiac arrhythmias showed no clear association with poor performance.
77-78% of poorly performing trotters exhibited at least one arrhythmic event during exercise with 6-10% prematurity criteria
8% of horses developed triplets, salvos, or paroxysmal tachyarrhythmias during peak exercise
15% of horses exhibited complex ventricular arrhythmias in the first 2 minutes of recovery
No association was found between airway diagnosis and arrhythmias during any exercise period; maximum average heart rate during peak exercise was an excellent predictor of complex ventricular arrhythmias during recovery
Evidence Base
A modified laryngoplasty approach promoting ankylosis of the cricoarytenoid joint.
Parente Eric J, Birks Eric K, Habecker Perry (2011) — Veterinary surgery : VS
Laser vocal cordectomy fails to effectively reduce respiratory noise in horses with laryngeal hemiplegia.
Brown Jennifer A, Derksen Frederik J, Stick John A et al. (2005) — Veterinary surgery : VS
Associations between Medical Disorders and Racing Outcomes in Poorly Performing Standardbred Trotter Racehorses: A Retrospective Study.
Lo Feudo Chiara Maria, Stucchi Luca, Stancari Giovanni et al. (2023) — Animals : an open access journal from MDPI
Cardiac arrhythmias in poorly performing Standardbred and Norwegian-Swedish Coldblooded trotters undergoing high-speed treadmill testing.
Slack J, Stefanovski D, Madsen T F et al. (2021) — Veterinary journal (London, England : 1997)
Hypercapnia and hyperlactatemia were positively associated with higher-grade arrhythmias during peak exercise in horses during poor performance evaluation on a high-speed treadmill.
Reef V B, Davidson E J, Slack J et al. (2020) — Veterinary journal (London, England : 1997)
Effect of ventriculectomy versus ventriculocordectomy on upper airway noise in draught horses with recurrent laryngeal neuropathy.
Cramp P, Derksen F J, Stick J A et al. (2009) — Equine veterinary journal
Laser fenestration of the dorsal pharyngeal recess does not correct experimentally induced dorsal nasopharyngeal collapse in horses.
Jeong Sharon, Bond Stephanie, Bayly Warwick et al. (2026) — Veterinary surgery : VS
Diagnosis and treatment of a congenital cervical tracheal diverticulum in an Arabian foal.
Fernandes T, Robin M G, Oikawa M A et al. (2025) — Journal of equine veterinary science
Bilateral laryngeal paralysis (aplegia) occurring late during the recovery of a horse after orthopaedic surgery
I. Lutvikadić, K. Hopster, B. Driessen (2025) — Equine Veterinary Education
Dynamic laryngeal collapse associated with poll flexion as a complication of laryngeal tie-forward surgery in three harness racehorses.
Vermedal Hanna, Strand Eric (2020) — Veterinary surgery : VS
Mycotic Rhinitis and Sinusitis in Florida Horses.
More Sunil Nivrutti, Hernandez Oscar, Castleman William L (2019) — Veterinary pathology
Soft tissue sarcomas in the pharyngeal region of a 5‐year‐old Quarter Horse mare
Pezzanite L. M., Devine D. V., Toll L. (2016) — Equine Veterinary Education
Diagnosis and treatment of dynamic collapse of the cricotracheal ligament in thoroughbred racehorses.
Kelly Padraig G, Pollock Patrick J (2015) — Veterinary surgery : VS
A novel treatment for dynamic laryngeal collapse associated with poll flexion: the modified checkrein.
Fjordbakk C T, Holcombe S, Fintl C et al. (2012) — Equine veterinary journal
Exercising videoendoscopic evaluation of 45 horses with respiratory noise and/or poor performance after laryngoplasty.
Davidson Elizabeth J, Martin Benson B, Rieger Randall H et al. (2010) — Veterinary surgery : VS
Congenital branchial apparatus malformation in a Haflinger colt.
David Florent, Savard Claudine, Drolet Richard et al. (2008) — Veterinary surgery : VS
A quantitative study of the equine soft palate using histomorphometry.
Richardson Lucy E, Wakley Glenn K, Franklin Samantha H (2006) — Veterinary journal (London, England : 1997)
Dynamic nasopharyngeal collapse in horses: What we know so far.
Jeong Sharon, Bond Stephanie L, Sole-Guitart Albert (2024) — Equine veterinary journal
Computational fluid dynamic analysis of upper airway procedures in equine larynges.
Tucker Michelle L, Wilson David G, Bergstrom Donald J et al. (2023) — Frontiers in veterinary science
Equine Welfare during Exercise: An Evaluation of Breathing, Breathlessness and Bridles.
Mellor David J, Beausoleil Ngaio J (2017) — Animals : an open access journal from MDPI
Show 5 more references
Dynamic respiratory endoscopy of Standardbred racehorses during qualifying races.
Priest D T, Cheetham J, Regner A L et al. (2012) — Equine veterinary journal
Biomechanical characterisation of equine laryngeal cartilage.
Passman S N, Cheetham J, Bonassar L J et al. (2011) — Equine veterinary journal
In vitro model for testing novel implants for equine laryngoplasty.
Cheetham Jon, Witte Thomas H, Soderholm Leo V et al. (2008) — Veterinary surgery : VS
Development of equine upper airway fluid mechanics model for Thoroughbred racehorses.
Rakesh V, Rakesh N G, Datta A K et al. (2008) — Equine veterinary journal
Implications of different degrees of arytenoid cartilage abduction on equine upper airway characteristics.
Rakesh V, Ducharme N G, Cheetham J et al. (2008) — Equine veterinary journal