A novel treatment for dynamic laryngeal collapse associated with poll flexion: the modified checkrein.

This research explores the effectiveness of a modified checkrein as a potential treatment to help alleviate dynamic laryngeal collapse (DLC), a performance-hindering upper airway disorder that affects Coldblooded trotter horses, particularly when they are under tension from reins. The results confirmed that the modified checkrein not only helped limit poll flexion (restricting the horse’s head and neck movement) but also improved the laryngeal condition and lessened airway obstruction, indicating its potential use as a conservative management tool for afflicted harness racing horses.

Introduction

The research focused on harness racehorses of the Coldblooded trotter breed commonly afflicted by Dynamic Laryngeal Collapse (DLC)- a condition where the horse’s larynx collapses under tension, obstructing the airway and affecting its performance. When these horses are driven with reins under tension, it induces a change in neck and head position known as poll flexion, exacerbating the airway obstruction. The main aim of the study was to test the effectiveness of a new device – the modified checkrein, and prove that this innovation could enhance laryngeal health by preventing excessive poll flexion.

Methods

• The study involved fourteen Norwegian Coldblooded Trotter racehorses previously diagnosed with DLC.
• These horses exercised on a high-speed treadmill at rates that took their heart rate to more than 200 beats per minute, thus simulating racing conditions.
• Researchers gathered data on the horses’ upper airway health through videoendoscopy recordings and tracheal pressure measurements.
• The tests were conducted once while using a conventional checkrein, and again using a modified checkrein.

Results

• The results showed that when fitted with a modified checkrein, not only was poll flexion effectively limited, but the horses also showed significant improvement in laryngeal health.
• There was no change in the head and neck position of the horses between phases of no rein tension and rein tension, indicating that the modified checkrein had successfully limited poll flexion.
• The scores from endoscopic examinations were significantly improved, proving that the modified checkrein had a positive impact on laryngeal health.
• When using the modified checkrein, tracheal peak inspiratory pressures were less negative, indicating the ease of airflow and diminished airway obstruction.

Conclusions

The modified checkrein was effective in avoiding the head and neck movement that leads to airway obstruction in trotter horses. It offers a promising solution as a conservative management tool for handling this performance-affecting ailment in harness racehorses. While surgical treatment and other management methods have had limited success, the modified checkrein presents a potential breakthrough in treating DLC in racehorses effectively.