Transendoscopic laser treatment of rostral displacement of the palatopharyngeal arch in four horses.

OBJECTIVE

To document the use and clinical outcome of transendoscopic laser techniques for treatment of rostral displacement of the palatopharyngeal arch (RDPA) in horses.

SUMMARY BACKGROUND DATA

Rostral displacement of the palatopharyngeal arch is a rare cause of upper respiratory noise and exercise intolerance in horses, and may be associated with abnormal laryngeal anatomy. There are few reports of successful treatment of this condition, and no reports of the treatment of RDPA using laser techniques.

METHODS

The diagnosis of RDPA was based on the presence of palatal tissue covering the dorsal aspect of the arytenoid cartilages on endoscopic examination. Either a neodymium:yttrium aluminum garnet (Nd:YAG) laser noncontact technique (1060 nm, 100 W continuous mode) or a diode laser contact technique (808 nm, 14 W, continuous mode) was used.

RESULTS

In 3 horses in which the Nd:YAG laser was used, displaced palatal tissue was not fully divided at surgery, but separated after latent thermal necrosis within 3 days. In the horse in which the diode laser was used, tissues were fully divided at the time of surgery. Two horses had abnormal laryngeal anatomy and laryngeal hemiplegia. One of these 2 horses was subjected to arytenoidectomy, and had limited success as a race-horse, while the other was retired as a broodmare. One of 2 horses with no other laryngeal abnormalities raced once unsuccessfully, while the other horse was never raced.

CONCLUSIONS

Rostral displacement of the palatopharyngeal arch may be corrected in standing horses using transendoscopic surgery, but despite successful ablation of displaced tissue the prognosis for athletic performance is poor.