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Published on: July 1, 2016
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Visual evoked potentials in the horse
1Department of Clinical Sciences, Swedish University of Agricultural Sciences, PO Box 7054, SE-750 07, Uppsala, Sweden. lena.strom@slu.se.
BMC Veterinary Research
|June 23, 2016
Summary
This study successfully recorded flash visual evoked potentials (FVEPs) in sedated horses, establishing a new clinical method for assessing post-retinal visual pathways. The equine FVEP waveform was characterized, showing potential for diagnosing visual impairments.
Area of Science:
- Veterinary Ophthalmology
- Neuroscience
- Electrodiagnostics
Background:
- Flash visual evoked potentials (FVEPs) are non-invasive recordings of central nervous system electrical activity in response to visual stimuli.
- While used in human medicine and other animal species, FVEP recording methods have not been established in horses.
- This technique could aid in evaluating visual impairment linked to post-retinal pathway disorders in equine patients.
Purpose of the Study:
- To develop and validate a clinical method for recording FVEPs in horses.
- To characterize the waveform morphology of FVEPs in normal, sedated horses.
Main Methods:
- Ten horses were sedated with detomidine, and scalp electrodes were used for recording.
- Optimal electrode placement was determined by evaluating various scalp positions.
- Flash electroretinograms (FERGs) were recorded concurrently, with nerve blocks and optic nerve transection used to confirm the origin of potentials.
Main Results:
- Consistent and reproducible FVEP waveforms (N1, P2, N2, P4 peaks) were recorded in all horses.
- Midline electrode placement rostral to the nuchal crest yielded the most reliable results.
- Optic nerve transection resulted in irreversible FVEP loss, confirming post-retinal origin.
Conclusions:
- A reliable method for recording FVEPs in sedated horses within a clinical setting has been established.
- The recorded potentials were confirmed to originate from post-retinal pathways.
- Further research is required to establish normative data and explore clinical applications for equine visual assessment.
