Preliminary investigation of somatosensory evoked potentials in equine headshaking.

This research investigates the neural activity of horses exhibiting headshaking behavior by applying a painful stimulus to a facial nerve and recording brain responses. Horses with headshaking syndrome displayed different responses to the stimulus compared to control horses, which suggests abnormal neural functioning in headshaking horses.

Objective of Study

• The main goal of this research was to analyze the neurophysiology of the trigeminal nerve in horses, specifically focusing on those that exhibit headshaking behaviors. This was done with the intention of establishing a refined technique to record the electrical activity in the horse’s cerebral cortex, essentially their brain activity, after applying an unpleasant electrical stimulus to the maxillary branch of the horse’s trigeminal nerve.

Methodology

• Eight horses were used in the study: four which exhibited headshaking behavior, and four healthy controls. To record the neurophysiological response, triphasic somatosensory evoked potentials (SEPs), were recorded using subcutaneous needle electrodes under general anaesthesia.
• In addition, dural electroencephalography (EEG) electrodes, which record brain’s electrical activities, were used to measure SEPs in another control horse and another horse demonstrating headshaking behavior.

Findings

• The results revealed that the headshaking horses showcased reduced middle latency and inter-peak intervals after the trigeminal nerve’s stimulation as compared to those without the condition. This variance implies that horses suffering from headshaking syndrome have different, abnormal neural responses to stimuli.
• The researcher’s inference from this study, therefore, is that headshaking syndrome in horses is likely due to unusual physiology of the trigeminal nerve.

Implication

• The outcomes of the research suggest that understanding the neurophysiology associated with the headshaking behavior in horses could help identify potential treatments or interventions.