Flash electroretinography in standing horses using the DTL microfiber electrode

Area of Science:

• Veterinary Ophthalmology
• Neurophysiology
• Animal Science

Background:

• Flash electroretinograms (ERGs) are crucial for evaluating retinal function in horses.
• Assessing ERGs in standing, sedated horses offers a practical alternative to general anesthesia.
• The DTL microfiber electrode provides a suitable tool for corneal recording.

Purpose of the Study:

• To evaluate a practical method for recording flash electroretinograms (ERGs) in sedated, standing horses.
• To assess the efficacy of the DTL microfiber electrode for ERG recording in equine subjects.
• To establish a safe and effective protocol for equine retinal function testing.

Main Methods:

• Horses were intravenously sedated with detomidine hydrochloride.
• Pupil dilation and auriculopalpebral nerve block were performed.
• ERGs were recorded using a DTL microfiber electrode on the cornea, with reference and ground electrodes placed conventionally. Ganzfeld stimulation was employed for photopic and scotopic responses.

Main Results:

• Good quality ERGs were recorded in sedated, standing horses.
• Median b-wave amplitudes and implicit times varied with light intensity and dark adaptation duration.
• A consistent increase in amplitude and implicit time was observed during dark adaptation, indicating normal retinal responses.

Conclusions:

• Detomidine hydrochloride sedation and the DTL microfiber electrode facilitate high-quality ERG recordings in horses.
• This protocol enables the detection of retinal functional problems without the risks of general anesthesia.
• The method is suitable for routine clinical assessment of equine retinal health.