One night you hear kicking and crashing coming from the barn and think you have a cast horse. You run to see if you can help, and what you find is a horse down on his side paddling as if galloping on the ground. His head and neck are extended and his eyes are slightly rolled back in their sockets, showing more white than normal and moving back and forth in a quick side-to-side motion. The horse does not respond to touch or sound and is oblivious to his surroundings. You can do nothing to help except to stay out of the way and ensure your own safety. The thrashing stops after 10-15 minutes that seem like hours. The horse stays down, is depressed, has a decreased response to stimulation, and acts somewhat blind. You call your veterinarian, who arrives and confirms that your horse had a seizure.

What I have described is the classic “grand-mal seizure.” This article will discuss the various types of seizures and the disease states that can cause them.

What’s a Seizure?

The most common seizure disorder is epilepsy, which is fortunately rare in the horse (it is actually controversial if “true” epilepsy actually occurs in the horse). There is little that can safely be done to help a 1,200-pound animal having a seizure.

To understand seizures, we need to review anatomy and physiology. Seizures occur when specific anatomical locations of the brain (forebrain and thalamus) are affected by some type of pathology. By definition, a seizure (also known as a fit, ictus, or convulsion) is considered abnormal behavior; seizures are physical expressions of abnormal electrical discharges in the forebrain neurons that initiate spontaneous, paroxysmal (spastic), involuntary movements.

The seizure event is broken into three phases–the pre-ictal, ictal, and post-ictal periods. Many people who suffer from epilepsy know they are going to have a seizure just before it happens. There might be a stran