Flash Visual Evoked Potentials in Conscious Horses: A Preliminary Study.

The study defines a reliable method for recording a specific type of neurological response to visual stimuli, known as flash visual evoked potentials (F-VEPs), in horses that are awake and calm. An experiment on how sedation influences the test results is also conducted.

Research Methodology and Procedures

• The researchers performed F-VEPs on 20 healthy adult horses without any sedation or use of other drugs.
• The purpose was to measure the average time it took for the most distinct positive peak (P53) to occur after a flash of light, as well as the times for the preceding and following negative peaks (N38 and N72).
• In addition to this, the researchers evaluated the mean peak-to-peak amplitudes (difference in values between positive and negative peaks).
• A test to observe the impact of sedation on the F-VEPs was conducted on three other horses. Two sedative drugs (xylazine and detomidine) were used, each administered in two different doses.

Results of the Study

• The mean latency for the P53 peak was found to be approximately 53 milliseconds, with the N38 and N72 peaks occurring at around 38 and 72 milliseconds respectively.
• The mean peak-to-peak amplitudes were around 12 and 23 microvolts.
• Compared to non-sedated state, sedation affected the results by lowering the amplitudes and increasing latencies, or by completely eliminating any response.

Interpretation and Future Application

• The researchers identified that a reliable F-VEP with a P53 latency in horses can be obtained without sedation, similar to the P2 peak noted in previous studies.
• This information could serve as a reference for future studies comparing neurological responses in horses with different diseases, following the same methodology.
• However, the effect of sedation on VEPs should be cautiously interpreted and requires further evaluation due to the limited number of samples used in this part of the study.