A study of an electrodiagnostic technique for the evaluation of equine recurrent laryngeal neuropathy.
Authors: Hawe C, Dixon P M, Mayhew I G
Journal: Equine veterinary journal
Summary
# Editorial Summary: Electrodiagnostic Assessment of Equine Recurrent Laryngeal Neuropathy Recurrent laryngeal neuropathy (RLN) represents a significant clinical problem in horses, particularly in certain breeds, yet the most practical diagnostic methods remain debated; Hawe and colleagues evaluated whether electrodiagnostic measurement of thoracolaryngeal reflex latency ('slap test') could reliably detect RLN when compared to established techniques including laryngeal muscle palpation, resting and post-exercise endoscopy, and both palpable and endoscopic responses to the reflex. In their examination of 35 Clydesdale horses and 10 control ponies, the researchers found that electrodiagnostic TLR latency measurement was not significantly more accurate than resting endoscopy alone for identifying RLN, nor were laryngeal muscle palpation or endoscopic TLR responses reliable diagnostic indicators. The prevalence of RLN in the Clydesdale population studied was striking—71% (25/35 horses)—with clinical presentation ranging from mild hemiparesis (46%) through to complete laryngeal paralysis (3%), though interestingly, physical conformation factors such as height or neck length showed no correlation with disease incidence or severity. For equine practitioners, this work underscores that resting endoscopy remains the most dependable screening tool for RLN and that electrodiagnostic testing does not offer sufficient diagnostic advantage to warrant routine clinical use, whilst highlighting the need for breed-specific monitoring strategies in predisposed populations like Clydesdales.
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Practical Takeaways
- •The 'slap test' (electrodiagnostic TLR measurement) should not be relied upon as a standalone diagnostic tool for RLN; resting endoscopy remains the more accurate diagnostic method
- •RLN is highly prevalent in Clydesdales (71%), suggesting breed-specific predisposition warrants further investigation
- •Physical conformation measurements cannot be used to predict or assess RLN severity in affected horses
Key Findings
- •Electrodiagnostic measurement of thoracolaryngeal reflex latency was not found to be an accurate test for evaluation of RLN compared to resting endoscopy
- •71% (25/35) of Clydesdale horses examined were affected by RLN, with 46% mild, 14% moderate, 9% severe hemiparesis, and 3% total paralysis
- •Laryngeal muscle palpation and endoscopic response to the thoracolaryngeal reflex were not accurate diagnostic tests for RLN
- •Physical traits such as height or neck length did not correlate with the incidence or severity of RLN in the examined population