Seizures in an Arabian foal due to suspected prolonged transient neonatal hypoparathyroidism

The applicability of ambulatory electroencephalography (AEEG) in healthy horses and horses with abnormal behaviour or clinical signs of epilepsy

BACKGROUND

Short-duration electroencephalography (EEG) recordings in horses are helpful in diagnosing intracranial disorders. Potentially, long-duration ambulatory EEG (AEEG) recordings in horses will enhance the chance of detecting abnormal brain activity independent of the presence of an insult.

OBJECTIVE

The objective of this study was to test if AEEG recordings in unsedated horses can be acquired and benefit diagnosing abnormal brain activity.

ANIMALS AND METHODS

Recordings were taken from 8 adult control horses and 10 patients suspected of intracranial abnormalities. Self-adhesive electrodes and the 'Porti-5' recording system were used. Filter settings were 0.5 Hz high pass and 35 Hz low pass. The records were analysed offline at a 50-200 μV/division and 10 seconds/division scale. Abnormal activity was defined as a spike or sharp wave, a period of generalised slow wave rhythmical activity or a generalised fast rhythmical discharge. The recording time ranged from 5 to 49 hours.

RESULTS

In the control group, one horse showed pathological activity. In the patient group, six out of nine horses showed abnormal activity during the recordings. Magnetic resonance imaging confirmed the presence of an intracranial mass in one patient. Long-term recordings of high quality can be obtained in unsedated horses by allowing daily activity using AEEG, resulting in a reasonable chance of recording (inter)ictal abnormal brain activity indicating epileptic or seizure-like activity in the absence of clinical signs or seizures.

CONCLUSIONS

It is concluded that abnormal behaviour can be expressed intermittently, and with the availability of AEEG a useful tool is added to the diagnostic scenario for horses.