Epilepsy in horses: aetiological classification and predictive factors.
Authors: Lacombe V A, Mayes M, Mosseri S, Reed S M, Fenner W R, Ou H T
Journal: Equine veterinary journal
Summary
# Epilepsy in Horses: Aetiological Classification and Predictive Factors Seizure classification in horses has historically lacked the systematic approach established in human and small animal medicine, hampering consistent diagnosis and treatment planning. This retrospective analysis of 104 horses presenting with seizures at a referral centre between 1988 and 2009 applied rigorous diagnostic protocols—including electroencephalography, cerebrospinal fluid analysis and computed tomography—to establish an aetiological framework, with logistic regression used to identify predictive factors for epilepsy development. Epilepsy (recurrent seizures) was diagnosed in 70% of cases, predominantly as cryptogenic (54.8%) or symptomatic (35.6%) presentations, whilst idiopathic epilepsy was remarkably rare at 2.7%; critically, horses presenting with partial rather than generalised seizures had a sevenfold greater likelihood of developing epilepsy, and normal neurological examination on admission alongside unprovoked seizure activity and epileptiform electroencephalogram findings all strongly predicted epilepsy diagnosis. These findings align with patterns documented in other species and offer clinicians practical diagnostic markers to support earlier identification of recurrent seizure disorders. Practitioners should recognise that cryptogenic cases—where no structural brain pathology is evident despite investigation—represent the largest diagnostic category, emphasising the need for comprehensive neurological workup and consideration of long-term management strategies even when imaging appears normal.
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Practical Takeaways
- •Develop a systematic approach to seizure classification in equine patients using history, clinical signs, and diagnostic imaging to differentiate epilepsy types and guide prognosis
- •Recognise that partial seizures, normal admission neurological exams, and unprovoked recurrent seizures are strong indicators of true epilepsy requiring long-term management
- •Understand that most equine seizures are symptomatic or cryptogenic rather than idiopathic, so thorough diagnostic investigation (EEG, CSF analysis, CT) is warranted to identify underlying causes
Key Findings
- •Epilepsy was identified in 70% of 104 horses with seizures, classified as symptomatic (35.6%), cryptogenic (54.8%), or idiopathic (2.7%)
- •Normal neurological examination on admission, unprovoked seizures, and paroxysmal epileptiform activity on EEG were strongly correlated with epilepsy diagnosis (P<0.05)
- •Horses with partial seizures had 7 times higher odds of epilepsy compared to horses with generalised seizures (P<0.05)
- •Seizure aetiology in most horses was symptomatic or cryptogenic, while reactive seizures and idiopathic epilepsy were less common