Description

Seizures in horses and humans are defined as abnormal motor or behavioral activity arising from the brain as a result of dysfunction in the frontal cortex. The sudden, uncontrolled burst of brain activity that precludes a seizure involves a small area of the horse's brain and may result in either a partial or a full-blown seizure.

A seizure is usually followed by a gradual return to normal with the horse standing within a few minutes. The horse may appear dazed or blind and exhibit signs of minor depression that may last several hours.

Seizures can occur in the horse secondary to a number of causes, including encephalitis, trauma, tumors, oxygen deprivation (foals), low blood glucose (foals), and toxicities.

Primary (idiopathic) epilepsy which is characterized by recurrent seizures is rare in horses. Epilepsy that is related to head trauma or brain inflammation is classified as acquired epilepsy and cases of acquired epilepsy usually begin several weeks after the injury.

A convulsive syndrome in weanling Arabian foals is the only recognized inherited form of epilepsy in horses. Seizures appear abruptly and can be mild to severe. Most foals outgrow the problem, and when diagnosed by a veterinarian, these seizures can usually be controlled with the use of an anticonvulsant.

Symptoms

Seizure activity (regardless of cause) is characterized by any or all of the following:

• Abnormal chewing/licking activity with twitching muscles around muzzle and jaw
• Sweating
• Rolling up of eyes
• Twitching, jerking muscles in the legs and body
• Paddling of the legs
• Loss of bladder/bowel control
• Sudden collapse (recumbency)
• Loss of consciousness usually for a short period of time
• Return to normal behavior

In mild cases, the horse may display incoordination, depression, and confusion, but not go down.

Causes

Viral or bacterial infections, tumors, trauma to the brain, oxygen deprivation, low blood glucose, toxins, medication overdoses, and metabolic disorders, including severe (end-stage) liver or kidney disease are the main causes of seizures in horses.

Prevention

Prevention of seizures in horses is best accomplished by keeping vaccinations current against causes of viral encephalitis (rabies, Eastern Equine Encephalitis, Western Equine Encephalitis, West Nile Virus) and bacterial diseases (tetanus, botulism) as recommended for your region by your veterinarian.

Post-foaling examinations should be performed on all newborn foals to assess overall health and any risk for neonatal encephalopathy which causes seizure.

Minimize environmental risks for trauma with proper trailer height, stall/barn ceiling height, and safe tying training for all horses to prevent head injuries or trauma.

Immediately have a veterinarian perform a thorough neurologic examination on any horse displaying abnormal motor or behavioral signs.

Treatment

Caution should always be taken when approaching a horse that is having a seizure. If a horse begins having a seizure, stand far enough away from him to avoid being injured if the horse collapses or kicks out. Do not attempt to calm or quiet the horse.

Notify your veterinarian as early as possible about the seizure. The horse will need to be examined to determine if the horse has sustained any injuries during the seizure and also to determine the cause of the seizure.

Initial treatment involves breaking prolonged seizure activity with medication such as diazepam (valium) and/or phenobarbital, and treatment/removal of any known or recognized causes for the seizures.

Riding a horse that has a seizure disorder is not recommended.