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What is a seizure or epilepsy?

A seizure, also known as a convulsion or fit, is a temporary, involuntary disturbance of normal brain function. If abnormal brain activity occurs in the motor cortex of the brain, it may cause uncontrollable muscle activity.

Epilepsy is a condition that involves repeated seizures that may occur alone or in clusters. These seizures may be infrequent and unpredictable, or they may occur at regular intervals. Seizures are one of the most frequently reported neurological conditions in dogs.

There are two main types of seizures in dogs: generalized (grand mal) and focal (partial).

• Generalized seizures cause loss of consciousness. All the muscles in the body move spastically and erratically. The legs may appear to paddle ineffectively. The head will often be drawn backward. The dog may urinate, defecate, or salivate.
• Focal/partial seizures involve only certain muscle groups and are characterized by behavioral changes. They may cause twitching on one side of the body and may or may not cause loss of consciousness. Focal seizures can progress to become generalized seizures.

What causes seizures?

There are many causes of seizures. Epilepsy that has no detectable cause is called idiopathic epilepsy. Idiopathic epilepsy is an inherited disorder in dogs, and its exact cause is unknown. Idiopathic epilepsy is the most common cause of seizures in dogs. Other causes include liver disease, kidney failure, brain tumors, brain trauma, and toxins.

Seizures often occur at times of changing brain activity, such as play or feeding time, or as the dog is falling asleep or waking up. Affected dogs can appear completely normal between seizures.

What happens during a typical seizure?

Seizures consist of three components:

1. The pre-ictal phase (aura) is a period of altered behavior in which a dog may hide, appear nervous, or seek out its owner. The dog may be restless, nervous, whining, shaking, or salivating. This phase may last from a few seconds to a few hours. This period precedes the seizure activity, as if the dog senses that something is about to occur.

2. The ictal phase is the period in which a seizure actively occurs. It can last from a few seconds to several minutes and can vary in appearance. The dog may show mild changes in mental awareness, such as a dazed look, mild shaking, staring aimlessly, and licking lips, or it may completely lose consciousness and body function.

A generalized seizure usually lasts for one to two minutes. If the seizure does not stop within five minutes, the dog is said to be in status epilepticus or prolonged seizure (outlined below). Dogs in status epilepticus require urgent treatment.

3. The post-ictal phase is the period immediately after the end of the seizure. This phase is characterized by a variety of signs, including confusion, disorientation, salivation, pacing, restlessness, and/or temporary blindness. There is no direct correlation between the severity of the seizure and the duration of the post-ictal phase.

Is a seizure painful or dangerous for my dog?

Despite the dramatic and violent appearance of a seizure, they are not painful, although your dog may feel confused and might panic. Contrary to popular belief, dogs do not swallow their tongues during a seizure. If you put your fingers or an object into her mouth, you will not help your pet and run a high risk of being bitten very badly or injuring your dog. The important thing is to keep your dog from falling or hurting herself by knocking objects onto herself. If she is on the ground, there is little chance of harm occurring.

A single seizure is rarely dangerous to a dog. However, if your dog has multiple seizures within a short time (cluster seizures) or if a seizure continues for longer than a few minutes, the body temperature begins to rise. If hyperthermia (elevated body temperature) develops due to a seizure, another set of problems must be addressed.

What is status epilepticus?

Status epilepticus is a serious and life-threatening situation in which a seizure lasts more than five minutes. Unless intravenous anticonvulsants are given immediately to stop the seizure activity, a dog may die or suffer irreversible brain damage. If status epilepticus occurs, you must seek treatment from a veterinarian immediately.

How is the cause of seizures determined?

After your dog has a seizure, your veterinarian will take a thorough history, concentrating on possible exposures to poisonous or hallucinogenic substances and any history of head trauma. Your veterinarian will also perform a physical examination, blood and urine tests, and sometimes an electrocardiogram (ECG). These tests rule out disorders of the liver, kidneys, heart, electrolytes, and blood sugar levels.

If these tests are normal and there is no exposure to poison or recent trauma, further diagnostics may be recommended, depending on the severity and frequency of the seizures. Occasional seizures (less frequently than once a month) are not as worrisome but they can become more frequent or more severe.

Specialized techniques may also be performed to look directly at the structure of the brain, such as a CT scan or MRI. Your veterinarian may recommend sampling cerebrospinal fluid (CSF — the fluid around the brain and spinal cord) to look for abnormalities that could contribute to diagnosis.

How can I help my veterinarian determine the cause of my dog’s seizures?

By carefully observing your dog during a seizure, you can provide valuable information to your veterinarian about the types of disease that may be causing the problem. Information about your dog’s lifestyle and history may also be important, including:

• At what age did the seizures begin and are they getting worse?
• Do the seizures occur at regular intervals or with no predictability?
• How often do the seizures occur and how long do they last?
• Have you noticed any association between seizures and sleep, excitement, feeding, etc.?
• Are there any other signs of illness (e.g., poor appetite, excessive drinking, reduced exercise)?
• Has your dog received any medications or supplements recently, including any flea control products or over-the-counter deworming medicine?
• What diet and nutritional supplements are given?
• Has there been any access or exposure to poisons or toxins?

How are seizures treated or prevented?

Treatment usually begins after a dog has:

• Two or more seizures within a six-month period
• Status epilepticus
• Cluster seizures
• A post-ictal period that is considered severe or longer than 24 hours
• Increasing seizure frequency and/or length
• Increasing seizure severity

The most commonly used medication to treat seizures in dogs is phenobarbital. Potassium bromide is another option. Newer anticonvulsants, such as zonisamide (Zonegran®) and levetiracetam (Keppra®) are becoming more popular. Combination therapy (multiple drugs) is often used for dogs that respond poorly to standard treatments.

It may be necessary to adjust the dose, frequency, and/or type of drug several times before determining the best treatment. This process can be frustrating, but finding the right treatment is important for your dog’s long-term health. Even with treatment, it may not be possible to completely prevent seizures. In some cases, the goal is to reduce seizures so your dog can have a good quality of life.

Once anticonvulsant medication is started, it will likely be required for the rest of the dog’s life. There is evidence that, if anticonvulsant medication is started and then discontinued, the dog may have a greater risk of developing more severe seizures in the future. Even normal dogs without a history of seizures or epilepsy may be induced into seizures if placed on anticonvulsant medication and then abruptly withdrawn from it. If anticonvulsant medication must be discontinued or changed for some reason, your veterinarian will give you specific instructions.

It is important to understand the following “golden rules” of seizure treatment:

• Always follow the instructions on the label. Both the dose and timing of the medication are important to maintain adequate drug levels in the bloodstream.
• Never run out of medication, as sudden withdrawal of treatment can lead to uncontrollable seizures.
• Inform your veterinarian when your supply is running low so a refill prescription can be arranged, particularly if it must be ordered from a specialty pharmacy.
• Keep the medication safe and away from children, as it can be a powerful sedative.
• Check with your veterinarian before giving other medications to your dog, including herbs and supplements.

What are the side effects of treatment?

Mild side effects are common, particularly at the beginning of treatment or following changes in the regime. The most common side effect is sedation/lethargy, but other signs can occur. Most side effects are temporary and disappear as your dog gets used to the medication. If side effects persist or seem severe, notify your veterinarian. Do not change the dose or timing of medication without consulting your veterinarian first.

Why is my dog still having seizures after starting the medication?

Sometimes, treatment will appear to not work, especially during the first month or two. In this case, first check that you are following the instructions on the medication label correctly. If you are, then the dosage and timing of the medication may need adjustment, your dog may require increased medication during period of stress, or the disease may be worsening. Consult your veterinarian for instructions.