Laser vocal cordectomy fails to effectively reduce respiratory noise in horses with laryngeal hemiplegia.

This research investigates the effect of a laser vocal cordectomy on respiratory noise and airway function in horses with induced laryngeal hemiplegia (LH), finding that the procedure doesn’t significantly improve the condition. Its recommendations are based on the analysis of data from six Standardbred horses observed before and after undergoing the procedure.

Methodology

• The research is based on an experimental study involving six Standardbred horses that showed no upper airway abnormalities at rest or during high-speed treadmill exercise.
• The researchers performed a series of tests on the horses before and after artificially inducing laryngeal hemiplegia through left recurrent laryngeal neurectomy (a procedure that paralyzes the vocal cord).
• Measurements primarily focused on respiratory sounds and inspiratory trans-upper airway pressure (P(Ui)). Tests were taken at baseline, and 14 days after LH was induced. Follow-up measurements were made 30, 60, 90, and 120 days after a laser cordectomy was performed on the left vocal cord of the horses.

Results

• The results showed a significant increase in P(Ui), sound level (SL), and the sound intensity of formant 2 (F(2)) and 3 (F(3)) in horses when LH was induced and they were exercising at their maximum heart rates (HR(max)).
• Laser vocal cordectomy had no effect on sound level (SL), or on the sound intensity of F(1) and F(3)), indicating that the procedure was unsuccessful in reducing respiratory noise in horses with LH.
• Although P(Ui) and the sound intensity of F(2) were significantly reduced at 30, 60, 90, and 120 days after surgery, they remained significantly different from baseline values, underlining that the procedure did not restore airway function to its original state.

Conclusions

• The main conclusion drawn from the research is that unilateral laser vocal cordectomy failed to efficiently reduce respiratory noise in horses with induced LH.
• This result suggests that the procedure’s effectiveness in alleviating upper airway obstruction is on par with bilateral ventriculocordectomy (surgical removal of both vocal cords), which also show limited efficacy.
• Given these findings, the research concludes that laser vocal cordectomy cannot be recommended as a treatment for upper airway noise in horses with LH.