A comparison of techniques to enhance the evaluation of equine laryngeal function.

This research aims to identify a simplified and conclusive method to evaluate the function of the larynx in horses, in order to diagnose idiopathic laryngeal hemiplegia (ILH), a condition characterized by a lack of movement of a specific part of the larynx.

Objective

• The main objective of this study is to find an efficient, direct method to evaluate laryngeal function and diagnose idiopathic laryngeal hemiplegia in horses. Researchers used seven horses for this study and attempted various techniques intended to stimulate the larynx.

Methods and Procedures

• Researchers experimented with four different techniques to stimulate laryngeal movements: nasal occlusion, exercise, swallowing, and administration of a respiratory stimulant.
• In addition, the impact of calming the horse down (sedation) and applying a twitch (a device used to calm horses) on endoscopic examination was also evaluated, as these techniques may influence the condition of the larynx.
• Furthermore, the cross-sectional area of the rima glottidis (the opening between the vocal folds) was measured in each horse at rest and after each technique was performed. Measuring this area can significantly help understand how the different techniques affect the larynx.

Findings

• The study found that neither nasal occlusion nor exercise resulted in a statistically significant difference in the size of the rima glottidis.
• The administration of the drug Doxapram hydrochloride was found to increase the area of the rima glottidis, while another drug, xylazine, caused this area to shrink. However, these drugs had no influence on the amount of asynchronous movement or shakiness of the arytenoid cartilages (two triangular pieces of cartilage in the larynx).
• Through this study, researchers concluded that manual occlusion of the external nares (uses hands to hold the nostrils shut) during endoscopy is a simple and effective way of studying arytenoid function, thus aiding in diagnosing idiopathic laryngeal hemiplegia.

Conclusions

• This study has a significant contribution to veterinary practice, especially in diagnosing idiopathic laryngeal hemiplegia in horses, an important condition affecting the laryngeal function.
• The findings suggest that simple procedures such as manual occlusion of the external nares can be effective in diagnosing and evaluating this condition, which could impart valuable knowledge to the field of equine healthcare.