Seizures in horses: diagnosis and classification.

Area of Science:

• Veterinary Neurology
• Comparative Neurology

Background:

• Seizures are common chronic neurologic disorders in humans and dogs, but less frequent in horses.
• A seizure is a clinical event, irrespective of its cause, which can be intracranial or extracranial.
• Epilepsy is defined as a brain disorder characterized by recurrent seizures.

Purpose of the Study:

• To review definitions and propose a standardized classification for seizures in horses.
• To facilitate a logical diagnostic approach and consistent communication for equine seizures.
• To discuss the challenges in the clinical workup of horses with seizures.

Main Methods:

• Review of existing definitions and classifications of seizures and epilepsy.
• Discussion of classification by seizure type (focal vs. generalized) and etiology (reactive, symptomatic, cryptogenic, idiopathic).
• Exploration of primary (genetic) versus secondary (acquired) epilepsy classification.

Main Results:

• Classification of seizures can be based on type or etiology, aiding diagnosis.
• Epilepsy is classified as primary (genetic) or secondary (acquired).
• Cryptogenic epilepsies (unknown cause) constitute the majority of cases in horses, similar to humans and dogs.

Conclusions:

• Standardized classification improves diagnosis and communication for equine seizures.
• Technical limitations in equine brain imaging pose challenges for identifying underlying causes.
• History, physical and neurologic examinations, clinical sign progression, and treatment response are essential for diagnosing horses with seizures, especially when advanced imaging is unavailable or inconclusive.