What is Juvenile Epilepsy in horses? What are the signs? Is there any treatment? What is the prognosis? Is JIE more common in certain breeds of horse? Is there a genetic component to JIE? Is any research being done on juvenile idiopathic epilepsy in horses?

What is Juvenile Idiopathic Epilepsy (JIE) in Horses?

Most everyone has heard of epilepsy; however, what is juvenile epilepsy in horses? While epilepsy is a chronic disorder of recurring seizures, juvenile epilepsy affects foals as early as 2 days after birth up to 6 months of age. These seizures usually occur in clusters over a three day period. (Aleman et al, 2006) The seizures affect the foal's muscles

and this type of seizure is classified as "tonic-clonic".

What are the symptoms?

• Blindness
• Lethargy
• Abnormal menace response aka menace reflex ("The menace response is one of three forms of blink reflex. It is the reflex blinking that occurs in response to the rapid approach of an object. The reflex comprises blinking of the eyelids, in order to protect the eyes from potential damage, but may also including turning of the head, neck, or even the trunk away from the optical stimulus that triggers the reflex. ...Stimulating the menace reflex is used as a diagnostic procedure in veterinary medicine, in order to determine whether an animal's visual system, in particular the cortical nerve, has suffered from nerve damage. ...") Menace Reflex
• Seizures
• Loss of nursing reflex
• Eating problems from weakened swallowing reflex
• Depression
• Twitching and Chewing motions
• Head pressing
• Muscle stiffness
• Loss of consciousness
• Falling over
• Thrashing
• Disorientation
• Pneumonia
• Loss of control of bodily functions during seizures

Is there a genetic component to JIE?

JIE is thought to have a genetic component; however, the gene is not yet identified.

Is JIE more common in certain breeds of horse?

JIE is thought to have a genetic component in the Arabian horse. Other breeds may have it, however, they lineage would probably show Arabian bloodlines.

Juvenile Idiopathic Epilepsy was first reported in Arabian horses of a young age.

Is there any treatment?

Anti-seizure medications such as phenobarbital and diazepam can be used to help control or lessen the severity and duration of the seizures.

What is the prognosis?

The foals usually outgrow JIE between the ages of 12 to 18 months. The disorder is usually not fatal; however, during seizures the animal may injure itself. The injuries could lead to death. Once JIE is outgrown the animal can live a normal and healthy life.

Studies Underway on JIE

Brooks Equine Genetics is currently starting to study Juvenile Idiopathic Epilepsy in Arabian Horse at the University of Florida. It is trying to identify the genetic cause of JIE. Also, University of California at Davis is studying JIE.

For information on JIE research contact:
Dr. Monica Aleman
Neuromuscular Disease Laboratory
University of California
One Shields Avenue
Davis, CA 95616
mraleman@ucdavis.edu

For More Information:

Genetic Disorders and the Arabian Horse
Research and Education Subcommittee on Genetic Disorders Juvenile Idiopathic Epilepsy (JIE)/Juvenile Epilepsy Syndrome (JES)