Objective— To compare upper airway mechanics, arterial blood gases, and tracheal contamination in horses with induced left laryngeal hemiplegia (recurrent laryngeal neuropathy [RLN]) treated by laryngoplasty/vocal cordectomy (LPVC) or modified partial arytenoidectomy (MPA).

Study Design— Repeated measures under the following conditions: Control, RLN, LPVC, and MPA.

Animals— Six horses.

Methods— Two trials were conducted under all conditions at 80% and 100% of maximal heart rate (HRmax). In Trial 1, arterial blood gases, tracheal and pharyngeal pressures, and laryngeal videoendoscopy were recorded. In Trial 2, upper airway pressure and airflow were determined. Tracheobronchial aspirates were performed after exercise to quantify airway contamination.

Results— Compared with control, RLN significantly increased inspiratory impedance and worsened exercise-induced hypoxemia. At 80% HRmax, LPVC restored most variables to control values. At 100% HRmax, LPVC improved all variables, but did not restore minute volume, arterial pH, and PaCO2. At 80% HRmax, MPA restored all variables except bicarbonate to control values. At 100% HRmax, MPA improved all variables, but did not statistically restore minute ventilation or bicarbonate level. Only minor differences were noted between LPVC and MPA. Both resulted in equivalent tracheal contamination.

Conclusions— Airway mechanics and arterial blood gas values were not restored to normal after either LPVC or MPA in horses exercising at HRmax. This does not affect ventilation at sub-maximal exercise, but has clinical implications at HRmax. Both procedures diminish normal laryngeal protective mechanisms.

Clinical Relevance— At sub-maximal exercise intensities both LPVC and MPA restore airway ventilation to normal. At maximal exercise the superiority of LPVC over MPA is slight.