Incidence of swallowing during exercise in horses with dorsal displacement of the soft palate

• Published in: Equine veterinary journal 2010-11, Vol.42 (8), p.732-737
• Main Authors: Pigott, J.H, Ducharme, N.G, Mitchell, L.M, Soderholm, L.V, Cheetham, J
• Format: Article
• Language: English
• Subjects: Airway Obstruction - veterinary; Airway Resistance - physiology; Animals; controlled; deglutition; Deglutition - physiology; digestive system diseases; disease diagnosis; dorsal displacement; dorsal displacement of the soft palate; Endoscopy - veterinary; Female; frequency; horse; horse diseases; Horse Diseases - pathology; Horse Diseases - physiopathology; Horses; Male; palate; Palate, Soft - abnormalities; Palate, Soft - pathology; physical activity; Physical Exertion - physiology; pressure; swallow; Videotape Recording
• ISSN: 0425-1644; 2042-3306
• DOI: 10.1111/j.2042-3306.2010.00116.x

Summary Reasons for performing study: The relationship between dorsal displacement of the soft palate (DDSP) and swallowing is unclear. Objective: To quantify the relationship between DDSP and swallowing in horses at exercise. Hypotheses: The frequency of swallowing increases immediately prior to DDSP in horses at exercise. Methods: Videoendoscopic and upper airway pressure data were collated from horses with a definitive diagnosis of DDSP at exercise. Horses with no upper airway abnormalities were matched by age, breed and sex and used as controls. Sixty‐nine horses were identified with a definitive diagnosis of DDSP during the study interval. Airway pressure data were available for 42 horses. Results: The majority of horses displaced at high exercising speeds while accelerating; a smaller number displaced during deceleration after peak speed had been reached. Horses swallowed significantly more frequently in the 1 min immediately preceding DDSP than in the control horses at equivalent speeds. DDSP at exercise results in a significant increase in tracheal expiratory pressure, a significant decrease in pharyngeal expiratory pressure and a significantly less negative pharyngeal inspiratory pressure compared to matched controls and compared to the pressures during the 1 min interval prior to DDSP. There was no significant difference between any measure of airway pressure before or after a swallow when examined at each time interval in the DDSP population. Conclusions: The frequency of swallowing decreases with increasing speed in normal horses. In contrast, the frequency of swallowing increases immediately prior to onset of DDSP. This is not a result of pharyngeal and tracheal pressure changes. Potential relevance: The increased frequency of swallowing observed prior to DDSP may be related to the aetiology of the disease.