Upper airway endoscopy in exercising horses: Findings in 164 barrel racing horses with respiratory clinical signs and/or poor performance.

The researchers conducted a study to determine the prevalence of upper airway obstructions in horses involved in barrel racing, a high-intensity equestrian event. Utilizing a technique known as overground endoscopy, the research team analyzed a sample of 164 performance horses experiencing respiratory issues or impaired performance. The findings suggest that a majority of the evaluated horses had two or more simultaneous obstructions, underlining the significance of overground endoscopy at varying exercise intensities.

Methodology

• The researchers utilized a method called ‘overground endoscopy’ (OGE) to investigate the upper respiratory tracts of 164 client-owned horses referred to them between 2014 and 2022.
• These horses were showing signs of respiratory issues (such as coughing and nosebleeds), strange behaviour (stress/anxiety, reluctance to enter the racing area, excessive head shaking), and/or poor performance in the arena.
• Every horse was subjected to a uniform exercise test with components of low and high speed. The exercise behaviour and reactions were recorded via videoendoscopy and evaluated by one experienced clinician.

Findings

• Of the 164 horses examined during exercise, only 24 didn’t exhibit any upper airway obstruction. The rest, 140 horses, showed some level of breathing difficulty.
• The obstructions were varied, with the large majority of horses showing multiple simultaneous issues. Nasopharyngeal collapse (NPC) was observed in 49%, palatal instability (PI) in 42%, intermittent dorsal displacement of the soft palate (DDSP) in 39%, vocal fold collapse (VFC) in 27%, recurrent laryngeal neuropathy (RLN) in 19%, ventro-medial luxation of the apex of the corniculate process of the arytenoid (VLAC) in 10%, medial deviation of the aryepiglottic fold (MDAF) in 6%, and cricotracheal ligament collapse in 6%.
• Further analysis found that NPC and RLN, in particular, were notably severe in their manifestation.

Implications and Conclusion

• The study indicates that co-existing upper airway obstructions (UAOs) are common among horses participating in barrel racing especially when exhibiting respiratory or behavioural symptoms or are underperforming. However, these issues couldn’t be associated with the horses’ ages or sexes.
• The study also highlighted the utility of OGEs at different exercise intensities as abnormalities were more frequently detected at low speeds (55%) than at high speeds (22%).
• The research therefore suggests the need for further in-depth investigation of equine respiratory health, especially in high-performance contexts.