Dorsal Displacement of the Soft Palate in Horses
Dorsal displacement of the soft palate is a condition of the upper respiratory tract that can limit performance in horses. It is a relatively common cause of upper respiratory noise during maximal exercise. During dorsal displacement of the soft palate, the free edge of the soft palate moves up to the epiglottis and creates a functional obstruction within the airway. The cross-sectional area of the throat is reduced, and airflow resistance and turbulence are increased.
The condition may result from several disease mechanisms. Inflammation of the upper respiratory tract due to infection may cause dysfunction of the nerves that control the soft palate. Similarly, inflamed lymph nodes can cause compression and irritation of the nerves. Inborn defects in the epiglottis may also contribute to dorsal displacement of the soft palate, due to insufficient tissue to maintain the soft palate in its normal location.
Dorsal displacement of the soft palate creates a characteristic gurgling breathing noise, primarily during exhaling, due to vibration of the soft palate. Horses may make no noise at the onset of exercise but displace their palate during high-speed exercise, causing them to “choke down.” Head position (flexed) may contribute to displacement.
The most effective treatment for dorsal displacement of the soft palate in young horses (2-year-olds) and horses with evidence of upper respiratory tract infection is rest and anti-inflammatory medication. Placing a tongue tie during exercise helps keep the palate in a better position and can improve signs. Various types of surgery can also be performed and a procedure called soft palate resection (staphylectomy) is frequently performed in horses with dorsal displacement of the soft palate. This procedure has a success rate of about 50%.
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