Dorsal displacement of the soft palate is a common cause of respiratory noise and exercise intolerance in racehorses.1–5 Its etiology is not completely known, although most investigators believe the disease is secondary to neuromuscular dysfunction of the soft palate.3 Various surgical procedures have been developed to treat DDSP in horses.3,6–8 Such procedures include sternohyoideus and sternothyroideus myectomy, sternothyroideus tenectomy, staphylectomy, oral palatopharyngoplasty, epiglottic augmentation, laryngeal tie forward, and laser palatoplasty.1,2,5,8–10
Laser palatoplasty has been used to stiffen the soft palate (ie, increase its elastic modulus) through laser-induced fibrosis. Laser palatoplasty has been used alone or in combination with other surgical procedures.2,10 Two studies2,10 of laser palatoplasty in horses have been performed. In one,2 standing diode laser palatoplasty was used in combination with sternothyroideus tenectomy, resulting in 50 of 52 horses returning to racing after surgery.2 In the other,10 a carbon dioxide laser via laryngotomy was used, leading to improved racing performance in 63% of treated horses afterward.
Because surgical lasers have been used to treat snoring in people, it has been speculated that laser palatoplasty in horses results in fibrosis of the soft palate.11 It is also believed that development of soft palate fibrosis following laser palatoplasty results in increased soft palate stiffness, which may lead to a decreased likelihood of soft palate displacement during exercise.2,10 However, to the authors' knowledge, this supposition has not been objectively evaluated. The purpose of the study reported here was to determine the effects of a diode laser on the soft palate following laser palatoplasty in horses. We hypothesized that diode laser palatoplasty would result in an increase in fibrosis and stiffening (elastic modulus) of the soft palate within 45 days after surgery.
Dorsal displacement of the soft palate
Magnetic resonance imaging
Cetacaine, Cetylite Industries Inc, Pennsauken, NJ.
Videoendoscope (1 m), Olympus America Inc, Lake Success, NY.
Endoscopic spraying device (type PW-5/6), Olympus America Inc, Lake Success, NY.
Bronchoesophageal grasping forceps, Sontec Instruments, Englewood, Colo.
Accuvet TM V50 laser, Lumenis Inc, Santa Clara, Calif.
SMA 600-μm bare fiber BFHF-603 (chisel tip), Biolitec, East Longmedow, Mass.
Beuthanasia solution, Schering-Plough Animal Health, Union City, NJ.
Sigma Excite 3.0-T HD System, CE Healthcare, Piscataway, NJ.
Adobe Photoshop CS4, Adobe Systems Inc, San Jose, Calif.
National Instruments LabVIEW, Vernier Software & Technology, Beaverton, Ore.
SAS, version 9.1, SAS Institute Inc, Cary, NC.
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