Variability of resting endoscopic grading for assessment of recurrent laryngeal neuropathy in horses.
Authors: Perkins J D, Salz R O, Schumacher J, Livesey L, Piercy R J, Barakzai S Z
Journal: Equine veterinary journal
Summary
# Editorial Summary: Variability in Resting Endoscopic Grading for Recurrent Laryngeal Neuropathy Recurrent laryngeal neuropathy (RLN) diagnosis relies heavily on endoscopic assessment of arytenoid cartilage movement at rest, yet the reliability of this subjective grading method had not been thoroughly quantified. Perkins and colleagues examined how much variability exists when experienced veterinarians use a standardised 7-grade system to score laryngeal function, analysing 270 draught horses across repeated examinations and multiple observers. Intraobserver agreement was excellent (86.7% weighted kappa), and interobserver concordance was good (76.5% weighted kappa), demonstrating that experienced examiners produce consistent, reproducible grades. However, when the same horses were re-examined after 24–48 hours, only 57.1% received identical grades, with moderate overall agreement (0.588 weighted kappa) between assessments—a concerning finding that suggests genuine biological variation or environmental influences affect presentation on the day. For practitioners involved in RLN diagnosis and management, this research confirms that the grading system itself is reliable in trained hands, but a single resting endoscopic examination may not capture a horse's true functional status. Follow-up examinations, dynamic endoscopy, or assessment under work should be considered when making important clinical decisions, particularly regarding surgical intervention or performance recommendations, as grading variability between sessions could obscure or exaggerate apparent disease progression.
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Practical Takeaways
- •A single endoscopic examination on one day may not reliably diagnose recurrent laryngeal neuropathy; consider repeat examinations 24-48 hours apart to increase diagnostic confidence
- •When interpreting endoscopic grades from different veterinarians, expect some variation (63% agreement); ideally use the same experienced examiner for serial assessments
- •Intraobserver reliability is good, so sequential examinations by the same veterinarian are more reliable for monitoring progression or treatment response than comparing grades across different examiners
Key Findings
- •Intraobserver agreement was high at 76.3% (weighted kappa 0.867) for experienced veterinarians using a 7-grade endoscopic system
- •Interobserver agreement was 63.1% (weighted kappa 0.765) between two examiners, indicating good but not excellent consistency
- •Only 57.1% of horses received the same grade when re-examined after 24-48 hours, suggesting moderate intrahorse daily variability (weighted kappa 0.588)
- •Single resting endoscopic examinations should be interpreted cautiously due to inherent daily variability in arytenoid cartilage movement assessment