Effect of bilateral tenectomy of the tensor veli palatini muscle on soft palate function in horses.
OBJECTIVE
To determine the effect of bilateral tenectomy of the tensor veli palatini muscle on soft palate and nasopharyngeal function in exercising horses.


METHODS
5 Standardbreds.


METHODS
Treadmill videoendoscopy was performed on 5 Standardbreds exercising at 50, 75, and 100% of the speed that produced maximum heart rate; tracheal and pharyngeal pressures were measured before and after surgery. Tenectomy of the tensor veli palatini muscle was performed bilaterally on each horse while under general anesthesia, using a transoral approach.


RESULTS
Peak inspiratory tracheal pressures were significantly (P = 0.016) more negative and there was a trend (P = 0.06) for peak pharyngeal inspiratory pressure to be less negative following bilateral tenectomy of the tensor veli palatini muscle, compared with preoperative values. The rostral half of the soft palate was unstable and collapsed dorsally into the nasopharynx during inspiration, causing partial obstruction of the nasopharynx. The caudal free margin of the soft palate remained ventral to the epiglottis, and dorsal displacement of the soft palate did not occur in any horse.


CONCLUSIONS
Bilateral tenectomy of the tensor veli palatini muscle did not cause dorsal displacement of the soft palate in horses while exercising at maximum heart rate, but resulted in collapse of the nasopharynx during inspiration.


CONCLUSIONS
Results of our study indicate that the tensor veli palatini muscle functions to support and dilate the nasopharynx during intense inspiratory efforts in horses by tensing the palatine aponeurosis.
Holcombe
S J
SJ
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing 48824, USA.
Derksen
F J
FJ
Stick
J A
JA
Robinson
N E
NE
D000768:Anesthesia, General; D000818:Animals; D004724:Endoscopy; D005080:Exercise Test / Q000662:veterinary; D005260:Female; D006339:Heart Rate; D006734:Horse Diseases; D006736:Horses; D001239:Inhalation; D008297:Male; D009059:Mouth Diseases / Q000601:surgery / Q000662:veterinary; D010160:Palate, Soft / Q000502:physiology*; D010614:Pharynx / Q000502:physiology; D013710:Tendons / Q000601:surgery*; D014132:Trachea / Q000502:physiology; D014741:Video Recording