## Overview Airway dynamics dysfunction refers to collapse or abnormal movement of upper airway structures that occurs only during exercise, when high negative pressures and airflow demands are present. Common forms include intermittent dorsal displacement of the soft palate, aryepiglottic fold collapse, vocal fold collapse, epiglottic retroversion, and dynamic nasopharyngeal collapse. These conditions are frequently invisible on resting endoscopy and require dynamic (overground or treadmill) endoscopy for definitive diagnosis. They limit performance by increasing airway resistance and reducing oxygen delivery. ## Causes The exact cause varies by structure. Many cases involve neuromuscular fatigue or inadequate dilator muscle activity relative to the extreme negative pressures generated at high speed. Concurrent inflammation, previous surgery, or conformational factors may contribute. Multiple forms of dynamic collapse often coexist in the same horse. ## Diagnosis Resting endoscopy may be normal. Dynamic endoscopy during exercise is required to identify the collapsing structures and their severity. History of exercise intolerance, abnormal respiratory noise (often inspiratory or gurgling), or sudden performance decline supports the diagnosis. Blood-gas analysis during exercise can quantify the physiologic impact. ## Treatment Treatment is tailored to the specific structures involved. Options include rest and anti-inflammatory therapy for inflammatory contributors, tack or bit changes, and surgical procedures such as tie-forward, laser resection, or prosthetic laryngoplasty variants. Prognosis depends on the structures affected and the severity of collapse. ## Recovery and Prognosis Prognosis ranges from good (selected mild or surgically correctable lesions) to guarded (severe dynamic nasopharyngeal collapse). Many horses improve with appropriate management or surgery, but recurrence or residual limitation is possible. ## Prevention No specific prevention exists. Maintaining respiratory health and avoiding excessive poll flexion in susceptible horses may reduce clinical expression.
exercise intolerance; abnormal respiratory noise during work (gurgling, roaring, or fluttering); sudden deceleration; normal appearance at rest
## Overview Airway dynamics dysfunction refers to collapse or abnormal movement of upper airway structures that occurs only during exercise, when high negative pressures and airflow demands are present. Common forms include intermittent dorsal displacement of the soft palate, aryepiglottic fold collapse, vocal fold collapse, epiglottic retroversion, and dynamic nasopharyngeal collapse. These conditions are frequently invisible on resting endoscopy and require dynamic (overground or treadmill) endoscopy for definitive diagnosis. They limit performance by increasing airway resistance and reducing oxygen delivery. ## Causes The exact cause varies by structure. Many cases involve neuromuscular fatigue or inadequate dilator muscle activity relative to the extreme negative pressures generated at high speed. Concurrent inflammation, previous surgery, or conformational factors may contribute. Multiple forms of dynamic collapse often coexist in the same horse. ## Diagnosis Resting endoscopy may be normal. Dynamic endoscopy during exercise is required to identify the collapsing structures and their severity. History of exercise intolerance, abnormal respiratory noise (often inspiratory or gurgling), or sudden performance decline supports the diagnosis. Blood-gas analysis during exercise can quantify the physiologic impact. ## Treatment Treatment is tailored to the specific structures involved. Options include rest and anti-inflammatory therapy for inflammatory contributors, tack or bit changes, and surgical procedures such as tie-forward, laser resection, or prosthetic laryngoplasty variants. Prognosis depends on the structures affected and the severity of collapse. ## Recovery and Prognosis Prognosis ranges from good (selected mild or surgically correctable lesions) to guarded (severe dynamic nasopharyngeal collapse). Many horses improve with appropriate management or surgery, but recurrence or residual limitation is possible. ## Prevention No specific prevention exists. Maintaining respiratory health and avoiding excessive poll flexion in susceptible horses may reduce clinical expression.
exercise intolerance; abnormal respiratory noise during work (gurgling, roaring, or fluttering); sudden deceleration; normal appearance at rest