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Dog: Epilepsy

General information

Other common/scientific names: seizures, idiopathic epilepsy, primary epilepsy

Epilepsy is a brain disorder characterized by repeated seizures. A seizure is a sudden, involuntary movement of the body caused by abnormal brain activity. Seizures are a sign of brain disease.

When we refer to epilepsy in dogs, we are usually referring to idiopathic or primary epilepsy where we have eliminated other causes of seizures such as tumors, strokes, infection, metabolic disease, trauma or toxins. Epilepsy caused by any of these other conditions is referred to as symptomatic, acquired or secondary epilepsy. This article will concentrate on idiopathic epilepsy which is the most common cause of seizures in the dog. Some studies estimate up to 4% of all dogs are affected.

With idiopathic epilepsy, the brain structure is normal but the brain’s function is abnormal. Seizures happen when a sudden burst of neurologic activity or hyperactivity occurs in the cerebrum of the brain. If this activity remains localized to a small area or one side of the cerebrum, it is referred to as a partial or focal seizure. On the other hand, generalized seizures happen when the abnormal burst of neurologic activity occurs over the entire cerebrum. These seizures are also referred to as grand mal seizures and are most common in the dog. They commonly occur at night when sleeping or relaxed.

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Abb. GGUJ8CSX: Schematic illustration of the central nervous system.
Epileptic seizures occur due to a burst of hyperactivity in the cerebrum.

Causes

The exact cause of idiopathic epilepsy is unknown, however certain breeds are more prone to developing epilepsy suggesting a genetic transmission. These breeds include Beagles, Labrador Retrievers, Golden Retrievers, Australian Shepherds and Keeshonds.

Symptoms

Prior to a generalized seizure, most dogs will experience a change in their behavior called an aura. These dogs may become anxious and restless, seeking attention or hiding from their owners. This stage may go unnoticed. With a generalized or grand mal seizure, the muscles stiffen and the dog will fall to their side with their legs extended and their head back. Loss of consciousness, excessive drooling, chomping of the jaws, loss of bladder and bowel control, barking and paddling occur. The average seizure lasts less than two minutes. Following the seizure, most dogs experience a period of time where they may appear blind and disorientated. This is called the post-ictal period and may last a few minutes to several hours.

During a partial seizure, the dog does not loss consciousness and is awake and alert. These seizures typically affect the face or one limb. The limb may buckle or the face begins to twitch. These seizures can develop into generalized seizures.

Status epilepticus refers to a state of continuous, uninterrupted seizures. These dogs are in danger of overheating, hypoxia, circulatory collapse, shock and death.

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Abb. GG11HFK7: Epilepsy in a dog.
This is a photograph of a dog in the post-ictal period.

Diagnosis

Diagnosis of idiopathic epilepsy is made after other conditions or diseases have been eliminated. Bloodwork consisting of a complete blood count (CBC), serum biochemistry and urinalysis is needed to rule out conditions which cause secondary epilepsy. The age of onset of seizures is important when diagnosing epilepsy. Seizures in dogs less than one year of age are usually a result of a congenital brain defect, encephalitis (infection of the brain) or intoxications. Idiopathic epilepsy is seen in purebred dogs 1-4 years of age. Seizures in older dogs are more frequently caused by tumors, strokes or metabolic disease.

Treatment

Epilepsy cannot be cured but the seizures can be controlled with medication. While most dogs with epilepsy recover to normal activity after seizuring, repeated seizures can lead to brain damage. Therefore, most veterinarians recommend medicating dogs that have more than 2-4 seizures a year. These dogs will need to be on life-long medication.

There are several human anticonvulsant medications used on dogs when treating epilepsy. The type of medication, dose and frequency of administration will need to be adjusted depending on the individual dog. Some dogs will require two different types of medication. Side effects of these types of medication are sedation and lethargy. The goal of treatment is to find the dose of medication which reduces the frequency and severity of seizures while minimizing the side effects. After the dog has been on anticonvulsant medication for 30 days, a blood test is performed to measure the level of medication. These results help determine the proper dose of medication needed. Depending on the dog, adjustments to the dosage may be needed during their lifetime. Annual drug levels are recommended to maintain the dog in therapeutic range.

Because most of these medications are eliminated by the liver, these dogs may develop liver damage over time. Monitoring liver function tests every 6-12 months can avoid this.

Prognosis

Most dogs respond well to these medications reducing the frequency and severity of seizures. These dogs can live normal, healthy lives. While these medications are fairly affordable, follow up and annual bloodwork can become costly. Some larger breed dogs become difficult to manage with medication. In cases where seizures cannot be controlled, euthanasia may be warranted.

Prevention

A dog with idiopathic epilepsy should not be used for breeding.

Tips

It is important to stay calm if your dog has a seizure. To avoid being bitten, do not place your hand near your dog’s mouth. If possible, protect your dog from injuring itself during a seizure. Remove other pets from the area. Record the time the seizure begins and ends. If the seizure lasts over 3 minutes, call your veterinarian immediately. If the seizure is less the 3 minutes and your dog recovers, you should contact your veterinarian for further instructions.

CAUTION

Do not change or discontinue the anticonvulsant medication without consulting your veterinarian. Sudden withdrawal of medication can result in status epilepticus.

Update version: 4/24/2014, © Copyright by www.enpevet.de
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