Interpretation of laryngeal function tests in the horse.

This research investigated laryngeal function in horses, revealing that idiopathic left-sided laryngeal paralysis was observed in 8.3% of the horses, and its presence was mostly noticeable after physical exertion. Furthermore, many horses exhibited asynchronous movement of the arytenoid cartilages, a condition often not evident until after exercise. Interestingly, some horses showed normal synchronized laryngeal movement when at rest but were later diagnosed with laryngeal hemiplegia post-exercise.

Investigation of Laryngeal Function

• The research was conducted on a sample of 169 thoroughbred horses on a specific farm.
• The principal focus was on idiopathic (of unknown cause) left-sided laryngeal paralysis. This specific ailment was detected in approximately 8.3% of the studied population.
• In most horses, the condition was evident only after physical activity, while arytenoid abduction and adduction, movements related with laryngeal function, appeared normal when the horses were at rest.

Observation of Arytenoid Cartilage Movement

• The research noticed an unusual pattern where nearly 55.6% of horses displayed asynchronous, or out of sync, arytenoid cartilage movement while resting.
• Interestingly, 86 of these horses were judged to be normal after they had exercised.
• On the other hand, six out of the 14 horses that were diagnosed with laryngeal hemiplegia, or one-sided paralysis of the larynx, exhibited normal synchronous arytenoid movement during rest.

Abnormal Inspiratory Noise

• An abnormal noise during inspiration, or inhalation, is often an important indicator of laryngeal disorders in horses.
• In the research, such noise was detectable in 11 out of the 14 horses diagnosed with laryngeal hemiplegia after exercise.
• However, an abnormal inspiratory noise was also produced by nine other horses in which laryngeal hemiplegia was not diagnosed, indicating other potential laryngeal function issues.