A quantitative study of the equine soft palate using histomorphometry

Dorsal displacement of the soft palate is a common cause of upper airway obstruction in racehorses and is of unknown aetiology. To determine whether the palate may displace for structural reasons, knowledge of the normal soft palate is required. The present study aimed to describe, qualitatively and quantitatively, the structure of the normal equine soft palate using histomorphometry. In soft palates from 12 Thoroughbreds, glandular tissue predominated (ca. 40% of total area), located mainly in the rostral and ventral regions. Rostrally, muscles attached to a tendinous aponeurosis located dorsal to the glandular tissue. Muscle was most abundant in the dorsal mid region and decreased caudally. The oral mucosa consisted of a non-keratinised stratified squamous epithelium whereas the nasopharyngeal mucosa was pseudostratified, columnar and ciliated. Elastin fibres were observed in the nasopharyngeal submucosa, becoming more prevalent caudally. The palates were bilaterally symmetrical although the proportion of tissue types varied considerably between individuals.