Staphylectomy:

Is probably the most common surgery preformed when a horse is diagnosed with a Dorsal displacement of the soft palate due to poor performance. The history usually involves a gurgling respiratory noise, usually on expiration due to the air caught between the soft palate that sits on top of the rostral tip of the Epiglottis (Normally it would sit beneath the epiglottis). The main reason surgery is elected is due to the horse trying very hard but is just not running his best or “making a Break” which means that he stops in the middle of the race. Horses have large lungs and usually an obstruction of the upper airway causes them to “gasp for air”. This is a simple surgery although the recovery is a messy one due to the connection of the surgery site and the trachea. Actually sometimes the horse keeps breathing from the surgery site till the granulation tissue fills in. The text books say 50% success but to my knowledge it is more then that.

For more info see: The Merck Veterinary Manual -Dorsal Displacement of the Soft Palate