Radiographic assessment of epiglottic length and pharyngeal and laryngeal diameters in the Thoroughbred.

The study was designed to assess the usefulness of lateral radiographs in determining pharyngeal disorders in thoroughbred horses. Findings showed that measurements obtained from radiographs, such as epiglottic length and pharyngeal and laryngeal diameters, closely aligned with actual measurements at postmortem, demonstrating the usefulness of radiographic imagery in diagnosing pharyngeal disorders.

Methodology and Findings

• The researchers focused on studying the length of the epiglottic cartilage and the diameters of the larynx and pharynx.
• Lateral radiographs of the pharyngeal region were used, which demonstrated effectiveness in identifying pharyngeal disorders like entrapment of the epiglottic cartilage and dorsal displacement of the soft palate.
• The length of the epiglottic cartilage, as deduced from the radiographs by measurement from the body of the thyroid cartilage to the tip of the epiglottis (referred to as thyroepiglottic length), closely matched the actual length found at postmortem examination.
• In 24 healthy thoroughbreds, the corrected thyroepiglottic length was approximately 8.76 cm. However, in nine thoroughbreds with entrapment of the epiglottic cartilage and six horses with dorsal displacement of the soft palate, the lengths were significantly shorter.
• The difference in nasopharyngeal diameter for thoroughbreds with dorsal displacement of the soft palate and healthy thoroughbreds was found to be significant, whereas no significant variation was observed in pharyngoepiglottic, laryngeal, or tracheal measurements between healthy and abnormal thoroughbreds.

Protocol and Conclusion

• For taking the radiographs, it was necessary to place the horse’s head in a normal resting position.
• The study observed that maximum dorsiflexion of the head, or bending it upwards, significantly increased the pharyngoepiglottic distance, while maximum ventriflexion, or bending it downwards, significantly decreased this distance.
• In dorsiflexion, the nasopharyngeal diameter was significantly greater than during ventriflexion. This indicates that the horse’s head position can impact the measurements.
• The investigation concluded that lateral pharyngeal radiographs can provide valuable diagnostic information for evaluating suspected pharyngeal disorders in thoroughbreds, particularly in cases of airway obstruction of the cranial part of the respiratory tract.