Equine Recurrent Laryngeal Neuropathy

Exercise increases the functional demand on the laryngeal airway. If recurrent laryngeal nerve dysfunction limits arytenoid abduction, the airway may become more restricted when the horse is working, even if resting examination findings appear less pronounced. This exercise-related change helps explain why performance assessment and, when necessary, dynamic airway evaluation are important.

The arytenoid cartilage helps maintain the open laryngeal passage during inspiration. Weakness or paralysis of its intrinsic abducting muscles reduces the available airway opening, particularly during exertion. A narrower passage increases resistance to inspiratory airflow, linking the local loss of movement with audible breathing changes and reduced exercise capacity.

The condition occurs most often on the left side, making side-specific laryngeal motion an important part of veterinary assessment. The examiner evaluates whether arytenoid movement is weakened or absent and relates that finding to the horse’s respiratory noise, performance history, and exercise tolerance. This approach connects anatomical asymmetry with clinically meaningful airway dysfunction.

Evaluation begins with the horse’s history, including abnormal inspiratory noise, reduced performance, or exercise intolerance. Airway endoscopy then allows direct assessment of laryngeal movement at rest, while functional grading records the severity of motion impairment. When resting findings do not fully explain the signs, examination during exercise can provide additional functional information.

Resting endoscopy shows laryngeal motion under non-exertional conditions, but the clinically important restriction may emerge when the horse is exercising. Exercise endoscopy can therefore assess airway function in the setting that produces respiratory noise or performance limitation. Comparing resting and exercise findings helps clarify whether laryngeal dysfunction is functionally relevant.

History, endoscopic observations, exercise findings, and functional grading together characterize the effect of laryngeal dysfunction on airway performance. That information supports decisions about management or procedures intended to improve airway function. It also provides a basis for interpreting whether the horse’s respiratory signs and performance problems are consistent with the observed laryngeal impairment.