Endoscopic Evaluations in Exercising Thoroughbred Yearlings

Endoscopic exams the upper respiratory tract (URT) are often standard procedure when veterinarians evaluate Thoroughbred yearlings possibly destined for the racetrack. These exams, which evaluate URT function, can satisfy sale conditions and assess a horse's suitability for racing.

A team of researchers at the University of Glasgow’s Weipers Centre Equine Hospital, in the United Kingdom, recently compared the results of endoscopic examinations in 57 horses at rest versus during exercise to evaluate the potential application of dynamic overground endoscopy when examining Thoroughbred yearlings, Padraig Kelly, MVB, MRCVS, said.

Kelly, an associate at the Weipers Centre Equine Hospital, explained, “Specifically, we wanted to investigate the prevalence of pathology of the upper respiratory tract during longeing exercise and to compare the results of resting and dynamic endoscopic examination.”

Researchers fitted the yearlings at a racing stable in the United Kingdom with a special bridle and saddle pad carrying the endoscope and related instrumentation. The team performed the endoscopic analysis while the horses were resting, while the animals were longed at the canter for five minutes (or until they were unable to sustain the gait), and immediately afterward. Researchers found significant variations in results derived from the resting phases versus the exercising phase.

“We identified a high prevalence of dorsal displacement of the soft palate, as well as a number of other pathologies that were not identified during resting endoscopic examination, such as vocal cord collapse and medial/axial deviation of the aryepiglottic folds (tissue spanning from the arytenoid to the epiglottis that collapses across the opening to the trachea)," Kelly explained. "These findings suggest that dynamic overground examination is a suitable means of investigating the URT in the Thoroughbred yearling, and that resting examination alone may not be sufficient to predict pathology during exercise.”

The examinations in the study were carried out “safely and without complication,” Kelly said.

“Further research is required to clarify the true significance of pathology identified during exercise in this age of horse and to establish how or if these pathologies affect future racing performance,” he noted.

The study, “Comparison of dynamic and resting endoscopy of the upper portion of the respiratory tract in 57 Thoroughbred yearlings,” will appear in an upcoming issue of the Equine Veterinary Journal

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