Summary A 3‐month‐old colt foal presented to the Philip Leverhulme Equine Hospital for investigation of progressive neurological signs. Diagnostic investigation included cerebrospinal fluid collection, which was performed under general anaesthesia. During this procedure, severe bradycardia which progressed to asystole occurred. Initial resuscitation was successful; however, the foal had clinical signs consistent with cerebral hypoxia post‐resuscitation and was euthanased the following day due to deterioration of neurological function. Asystole was presumed due to a Cushing‐type reflex as a result of changes in intracranial pressure during the sampling procedure.