Effects of ventriculectomy, prosthetic laryngoplasty, and exercise on upper airway function in horses with induced left laryngeal hemiplegia.

This research investigates the impact of certain surgical procedures, specifically ventriculectomy and prosthetic laryngoplasty, on the upper airway function and gas exchange in horses with an induced condition called left laryngeal hemiplegia. The effects on different levels of exercise were also examined.

Overview of the Research

• The study involved five adult horses that were trained to perform varying degrees of exercise on a treadmill — standing, trotting, and galloping.
• Various parameters such as inspiratory and expiratory airflows, transupper airway pressures, and blood gas tensions were measured. Heart rate was also monitored.
• The horses underwent left recurrent laryngeal neurectomy (LRLN), followed by ventriculectomy and prosthetic laryngoplasty.
• Observations and measurements were taken at different time intervals: before LRLN procedure (baseline), 14 days after LRLN, 30 days after ventriculectomy, and 14 days after prosthetic laryngoplasty.

Key Findings

• Before the LRLN procedure, the researchers identified a noticeable increase in heart rate, respiratory frequency, airflow rates, airway pressures, hemoglobin (Hb) content, and carbon dioxide pressure (PaCO2) in response to increased treadmill speed. Noteworthy were decreases in oxygen pressure (PaO2), pH, and bicarbonate values.
• Following LRLN, the resistance to airflow during inspiration, the intra-airway pressure during inspiration, and carbon dioxide pressures significantly increased during trotting and galloping. Maximum obtained during inspiration and respiratory rate significantly decreased during galloping.
• There were no significant changes seen after LRLN in terms of expiratory airway pressure, maximum volume expired, heart rate, oxygen pressure, pH, Hb content, or the resistance to airflow during expiration.

Conclusions

• The study provides valuable insights into the effects of LRLN, ventriculectomy, and prosthetic laryngoplasty on airway dynamics in horses, especially during different levels of exercise.
• It demonstrates how the surgical procedures and induced left laryngeal hemiplegia influence airflow, airway pressures, gas exchange, blood chemistry and heart rates in horses.
• The overall findings can contribute to developments in equine healthcare, particularly in the management and treatment of respiratory disorders.