The effect of bilateral glossopharyngeal nerve anaesthesia on swallowing in horses.

This research article studied the impact of anesthesia on the glossopharyngeal nerves in horses to draw conclusions as to whether it would cause swallowing issues. The researchers found no significant alterations in swallowing due to nerve anesthesia, hence indicating that the glossopharyngeal nerve function may not be essential for normal swallowing in health horses.

Objective

• The main goal of the study was to find out if applying bilateral glossopharyngeal nerve anesthesia would trigger dysphagia in horses or bring about noticeable changes in their swallowing rhythm, function, or sequence.

Methodology

• Swallowing functionality of six normal horses with and without bilateral glossopharyngeal nerve anesthesia was critically examined.
• The swallowing dynamics were evaluated both subjectively and objectively through methods like calculating the time required from food prehension to swallowing, counting the number of tongue movements until the initiation of swallowing, measuring the depth of the bolus at the base of the tongue before the commencement of swallowing, and checking for cases of tracheal aspiration through fluoroscopy and endoscopy.

Findings

• No proof of tracheal aspiration or dysphagia was found in horses before or after the bilateral glossopharyngeal nerve block.
• No perceptible variations in the function or sequence of swallowing were found in horses with the nerves blocked as compared to those without the block.
• However, in horses with nerve block, there was a trend of increase in the number of tongue pushes and the time taken to swallow.

Conclusions

• From their study, researchers concluded that the functioning of the glossopharyngeal nerves may not be a critical factor in regular swallowing in horses who are otherwise healthy.
• Another clinical conclusion was that using a standard swallowing test to check for glossopharyngeal nerve function is not appropriate. Additionally, it was suggested that dysphagic horses should not be assumed to have a dysfunction in the glossopharyngeal nerve.