Seizures are a common problem in horses and there are a number of recognizable forms. It can manifest as an alteration in mental state such as fainting, tonic (rigid muscles) or clonic (spastic muscles) movements, or convulsions. Generally seizures can be divided into primary seizures, also known as idiopathic epilepsy, and secondary seizures which are caused by a identifiable disease processes. Primary seizures can further be divided into juvenile epilepsy, adult onset epilepsy, and narcolepsy. The number of diseases that can cause secondary seizures is very long:

• trauma
• infectious and inflammatory diseases of the brain
• toxins
• toxic substances
• nutritional deficiencies
• liver and renal disease

This article provides an overview of seizures in horses, ways to differentiate the various causes, treatment, and prognosis. Also, links to other resources are provided.

Seizures are disturbances in the electrical activity of the brain. Because the brain is responsible for so many different activities there is a large range of different symptoms that can be interpreted as seizure activity. Seizures can cause involuntary changes in body movement or function, sensation, awareness, or behavior and in horses is often associated with falling down, loss of conscientiousness, and/or involuntary contraction of a group of muscles. It may last from a few seconds to a continuous seizure that will not stop without intervention which is rare in horses. Seizures are be preceeded by a "predomal stage" of depression or excitement and then the seizure is followed by a "postictal" period of depression.

Many seizure activities in humans involve personal experiences like marching numbness of a part of the body, a brief loss of memory, sparkling or flashes, sensing an unpleasant odor, a strange abdominal sensation or a sensation of fear. If we consider that some horses have similar problems it is difficult to say how these sensations might present. Could that recurrent undiagnosed colic actually be seizure activity?