Study: Throat Anatomy Differs in DDSP Horses

Horses with persistent dorsal displacement of the soft palate (DDSP), an important performance-limiting abnormality of the upper respiratory tract, have a different anatomic location of the larynx than horses with only intermittent DDSP, report Cornell University researchers.

DDSP affects approximately 10% to 20% of racehorses and is diagnosed by observing the caudal border of the soft palate dorsal to the epiglottis for more than 8 seconds. The condition causes an expiratory obstruction, which reduces the amount of air that is inhaled or exhaled per minute, resulting in hypoxemia (oxygen deficiency).

While intermittent DDSP is more common, persistent DDSP is considered a performance-ending disease (rather than simply performance-limiting) because of the constant obstruction of the respiratory tract.

To test the theory that horses with persistent DDSP have a different laryngohyoid position than horses with only intermittent DDSP, researchers reviewed medical records and radiographs of horses with both forms of DDSP.

According to the authors, compared to intermittent DDSP, horses with persistent DDSP had caudal descent of the larynx (on average 13mm difference).

The researchers also found that of the 15 horses undergoing a tie-forward surgery for treatment of persistent DDSP (with or without trimming of the edge of the soft palate), 13 returned to racing. This data prompted the authors to conclude that "persistent DDSP is a treatable condition."

The study, "Successful treatment of persistent dorsal displacement of the soft palate and evaluation of laryngohyoid position in 15 racehorses," is scheduled to be published in an upcoming edition of the Equine Veterinary Journal. The abstract is available online.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.