Videoendoscopic assessment of dynamic laryngeal function during exercise in horses with grade-III left laryngeal hemiparesis at rest: 26 cases (1992-1995).

This research investigates how videoendoscopy can be used to evaluate the laryngeal function of racehorses suffering from grade-III left laryngeal hemiparesis at rest during high-speed treadmill exercise. It also explores the treatment outcomes for these horses.

Research Methodology

• The study, conducted retrospectively, involved 26 racehorses diagnosed with grade-III left laryngeal hemiparesis at rest.
• Videoendoscopy was employed to evaluate the larynx of the horses both at rest and during exercise. This enables the researchers to observe the degree of arytenoid cartilage abduction which took place during exercise.
• Depending on this abduction degree, horses were classified as having grade-IIIA, -IIIB, or -IIIC laryngeal hemiparesis.
• Postoperative racing performance was gauged by examining race records and conducting telephone surveys.

Research Findings

• A significant majority of the horses, 77%, had grade-IIIC laryngeal hemiparesis. This indicated severe dynamic laryngeal collapse during exercise.
• Out of the 18 horses that underwent surgery in the grade-IIIC group, nine displayed improved racing performance after treatment.
• 19% of horses showed grade-IIIB laryngeal hemiparesis, where the left arytenoid cartilage and the vocal fold remained in an incompletely abducted position during exercise. Among the four that underwent surgery, one showed improved performance.
• Only one horse had grade-IIIA laryngeal hemiparesis, demonstrating full abduction of arytenoid cartilage during exercise. For this horse, surgery was not performed.

Conclusions

• Videoendoscopy proves to be a successful tool in assessing dynamic laryngeal function in racehorses with grade-III left laryngeal hemiparesis at rest.
• By enabling detailed observation of the larynx, it helps in accurate diagnosis and treatment of the ailment.
• The study also helps provide some insight into postoperative performance, although results varied widely with different grades of laryngeal hemiparesis.