Laser vocal cordectomy fails to effectively reduce respiratory noise in horses with laryngeal hemiplegia.
OBJECTIVE
To report the effect of unilateral laser vocal cordectomy on respiratory noise and airway function in horses with experimentally induced laryngeal hemiplegia (LH).


METHODS
Experimental study.


METHODS
Six Standardbred horses without upper airway abnormalities at rest or during high-speed treadmill exercise.


METHODS
Respiratory sounds and inspiratory trans-upper airway pressure (P(Ui)) were measured before (baseline) and 14 days after induction of LH by left recurrent laryngeal neurectomy, and again 30, 60, 90, and 120 days after endoscopically assisted laser cordectomy of the left vocal cord. Data were collected with the horses exercising on a treadmill at a speed producing maximum heart rate (HR(max)).


RESULTS
In horses exercising at HR(max), induction of LH caused a significant increase in P(Ui), sound level (SL), and the sound intensity of formant 2 (F(2)) and 3 (F(3)). The sound intensity of formant 1 (F(1)) was unaffected by induction of LH. Laser vocal cordectomy had no effect on SL, or on the sound intensity of F(1) and F(3). At 30, 60, 90, and 120 days after surgery, P(Ui) and the sound intensity of F(2) were significantly reduced, but these variables remained significantly different from baseline values.


CONCLUSIONS
Unilateral laser vocal cordectomy did not effectively improve upper airway noise in horses with LH. The procedure decreased upper airway obstruction to the same degree as bilateral ventriculocordectomy.


CONCLUSIONS
Currently, laser vocal cordectomy cannot be recommended for the treatment of upper airway noise in horses with LH.
Brown
Jennifer A
JA
Department of Large Animal Clinical Sciences, G-314 Veterinary Medical Center, Michigan State University, East Lansing, MI 48824-1314, USA.
Derksen
Frederik J
FJ
Stick
John A
JA
Hartmann
William M
WM
Robinson
N Edward
NE
D000818:Animals; D005260:Female; D006734:Horse Diseases / Q000503:physiopathology / Q000601:surgery*; D006736:Horses; D008297:Male; D010805:Physical Conditioning, Animal; D012129:Respiratory Function Tests / Q000662:veterinary; D012135:Respiratory Sounds; D016896:Treatment Outcome; D014826:Vocal Cord Paralysis / Q000601:surgery / Q000662:veterinary*; D014827:Vocal Cords / Q000503:physiopathology / Q000601:surgery*