Effect of poll flexion and dynamic laryngeal collapse on tracheal pressure in Norwegian Coldblooded Trotter racehorses.

The research investigated the impact of dynamic laryngeal collapse (DLC) – a breathing problem in the horse’s upper respiratory tract that is strongly linked to the flexing of the horse’s neck (poll flexion) – on tracheal pressure in Norwegian Coldblooded Trotter racehorses. The study compares airway mechanics in affected and elite horses, revealing that induced neck bending increases inspiratory pressure, which is more severe in horses with DLC.

Research Objectives

• The primary goal of this study was to ascertain whether Norwegian Coldblooded Trotters (NCTs) that suffer from DLC, related to neck flexing, vary from healthy, high-performing NCTs based on simple airway mechanics measurements.

Research Methods

• The researchers used five healthy elite NCTs and six NCTs that were previously diagnosed with DLC for this experiment.
• While continuous tracheal pressure measurements were taken, the horses underwent treadmill videoendoscopy.
• Different head positions were used for the horses during exercise with heart rates above 200 beats/min. This included free carriage and induced neck flexion.

Research Findings

• The researchers noted that the peak inspiratory (breathing in) tracheal pressures were more negative for horses affected by DLC compared to the elite horses, indicating more severe breathing problems.
• These differences were only significant during exercise phases when the horse’s head was bent down (poll flexed).
• The head position during exercise significantly impacted the peak inspiratory pressure for both the elite and affected horses.

Research Conclusions

• The experimentation demonstrated that neck bending significantly impacts peak inspiratory pressure in all horses.
• However, horses affected by DLC experienced much more negative peak inspiratory pressures.
• Based on the tracheal pressure measurements gathered in the study, the researchers concluded that DLC in NCTs is a severe obstruction in the upper respiratory tract induced by neck bending.