Comparison of two sedation protocols for long electroretinography in horses using the Koijman electrode.
Authors: Ignacio Corradini, Del Mar López-Murcia María, Marta Barba, Sina Zebarjadian, Vicent Rodilla, Aloma Mayordomo-Febrer
Journal: BMC veterinary research
Summary
Electroretinography (ERG) is essential for diagnosing retinal disease in horses, yet standardisation of testing protocols remains limited, particularly regarding electrode selection and sedation management. Researchers evaluated whether adding butorphanol to detomidine sedation would improve the quality of ERG recordings using the Koijman electrode—a device validated in canine ophthalmology but previously untested in equines—employing a randomised crossover design with seven mares and measuring waveform parameters and artefact rates under both protocols. The combination of detomidine and butorphanol produced electroretinograms with fewer artefacts relative to valid recordings compared with detomidine alone, whilst maintaining comparable amplitude and implicit time values across both groups. This finding suggests that opioid co-sedation enhances recording quality by reducing muscular and electrical noise, which may allow for improved diagnostic confidence without compromising the fundamental electrophysiological parameters used to assess retinal function. For equine practitioners performing ERG examinations, adopting a two-drug sedation protocol could improve test reliability and reduce the need for repeated recordings, ultimately supporting more accurate diagnosis of vision-threatening pathology in performance and leisure horses.
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Practical Takeaways
- •Electroretinography is now a practical diagnostic tool for equine retinal disease using the Koijman electrode with either sedation protocol
- •Detomidine with or without butorphanol provides adequate sedation for the procedure, giving practitioners flexibility in drug selection based on individual horse needs
- •This test can help diagnose vision-threatening conditions in sport and leisure horses before they impact performance or safety
Key Findings
- •Electroretinography using the Koijman electrode is feasible in sedated horses with standardized protocols
- •Detomidine alone and detomidine plus butorphanol both produced interpretable electroretinograms in a crossover study design
- •The Koijman electrode and RETI-port system can be successfully applied to equine ophthalmology for retinal outer segment assessment