Equine Dorsal Displacement of the Soft Palate Study Guide

Overview and Clinical Importance

Dorsal Displacement of the Soft Palate (DDSP) is a performance-limiting upper respiratory tract condition that occurs when the caudal free margin of the soft palate displaces dorsal to the epiglottis. This creates a functional airway obstruction during expiration, resulting in reduced airflow to the lungs and a characteristic gurgling respiratory noise. DDSP is one of the most common causes of poor performance in athletic horses, particularly Thoroughbred and Standardbred racehorses.

Horses are obligate nasal breathers, meaning they breathe exclusively through their nostrils under normal conditions. The soft palate forms an airtight seal with the epiglottis, separating the nasopharynx from the oropharynx. When DDSP occurs, this seal is disrupted, causing the soft palate to act like a parachute during expiration, dramatically reducing airflow and oxygen delivery to working muscles.

Relevant Anatomy

The Soft Palate

The soft palate is a musculomucosal sheet approximately 15 cm (6 inches) long that separates the nasopharynx (dorsal compartment) from the oropharynx (ventral compartment). The caudal free border of the soft palate normally fits snugly around the base of the epiglottis, creating a tight seal that allows the horse to breathe exclusively through its nose.