Association of owner‐reported noise with findings during dynamic respiratory endoscopy in Thoroughbred racehorses

Abstract

To determine the association between owner-reported noise and findings during dynamic respiratory endoscopy (DRE) in a large case series. The sensitivity of owner-reported noise for dynamic upper respiratory tract obstructions in horses is low, and the specificity is high. One hundred horses underwent DRE for the investigation of abnormal respiratory noise and/or poor performance. The association of abnormal noise with findings during DRE was evaluated. Eighty-five horses underwent DRE for the investigation of abnormal respiratory noise. Of these, 82% were found to have one or more obstructive upper respiratory tract abnormalities during DRE. Forty-eight percent of horses reported to gurgle, rattle or make a rough noise were diagnosed with solitary palatal dysfunction. A further 24% with this history showed palatal dysfunction in combination with an additional abnormality. Twenty-seven percent of horses with a history of whistling or roaring showed some degree of recurrent laryngeal neuropathy. Seven percent of horses with a history of whistling or roaring had vocal cord collapse as a solitary condition, whereas 40% had vocal cord collapse and another abnormality. The sensitivity of abnormal respiratory noise for any obstruction of the upper portion of the respiratory tract was high (84%), while the specificity was low (25%). Characteristic owner reported noise patterns showed moderate to low sensitivity for specific conditions. Whistling and roaring showed the highest specificity (≥80%) for laryngeal dysfunction. Diagnosis of upper respiratory tract obstructions based solely on owner-reported noise and performance history may result in incomplete diagnoses. DRE should be performed in horses with abnormal respiratory noise to rule out complex conditions of the upper portion of the respiratory tract.