Understanding Your Pet's EpilepsyDe

Understanding Your Pet's Epilepsy

Dennis O'Brien, DVM, PhD
Diplomate, ACVIM, Specialty of Neurology
University of Missouri, College of Veterinary Medicine
"All the most acute, most powerful, and most deadly diseases, and those most difficult to be understood ... fall upon the brain."
--Hippocrates
Epilepsy was recognized in ancient times and was undoubtedly one of the "difficult" diseases Hippocrates referred to. Understanding what causes seizures, how epilepsy is treated and how current research may help decrease the incidence of the disease, will help you deal with the condition in your pet.


See your veterinarian


Your veterinarian is the person to ask
what's best for your pet.
Your veterinarian will be your best source for advice about your pet's health. They know your pet, what treatments have been tried in the past, what was found on examination, and your pet's other medical problems.
Be an intelligent consumer. Educate yourself about your pet's disease and don't be afraid to ask questions. If you don't understand why a test is being run or a treatment recommended, your veterinarian will be able to explain why this will help your pet.
Remember anyone can post anything on the Internet so there is no guarantee the information is valid unless it comes from a reputable source. Share what you learn with your veterinarian. They can help you distinguish information that may be helpful from ideas that may be useless or even dangerous for your pet’s individual needs.
The information in this site is provided to help you understand the things your veterinarian will be discussing with you and may help stimulate discussion of the options available.
We cannot directly advise you on how to treat your pet. If your pet is having serious problems, you may wish to ask your veterinarian to refer you to a nearby Veterinary Neurologist (a specialist in diseases of the nervous system like epilepsy). To find a Board Certified Neurologist near you, go to the American College of Veterinary Internal Medicine homepage and search the "Find an ACVIM specialist near you" database. Information about the neurology service at the University of Missouri, College of Veterinary Medicine can be found at www.vmth.missouri.edu

Key points

If you have a pet with epilepsy, these are some of the key points for you to remember. They are discussed in more detail elsewhere:

Don't change or discontinue medication without consulting your veterinarian.
See your veterinarian at least once a year for follow-up visits.
If your pet has a seizure longer than 5-10 minutes or 3 seizures in a day, seek veterinary care immediately.
Be skeptical of exorbitant claims of treatments.
Remember, live with epilepsy not for epilepsy. With appropriate treatment, most dogs have far more good days than bad ones. Enjoy all those good days! Enjoy your life and your pet. They have a serious disease, but don't let that keep you from enjoying the time you have with them.

What is epilepsy?


Epilepsy refers to repeated seizures
over time. Idiopathic means we can't
find an underlying cause of the seizures.
Epilepsy simply refers to repeated seizures. Seizures may occur as a one time event in an animal from a variety of causes, but only if the seizures repeat again and again over a period of time do we call it epilepsy. Seizures are a sign of brain disease the same way a cough is a sign of lung disease. Saying an animal has epilepsy is like saying it has a chronic cough; it is a sign of a problem which isn't going away. Anything which damages the brain in the right area can cause epilepsy. If we can identify the cause of the seizures, say a brain tumor or a stroke, then we say the pet has symptomatic (or secondary) epilepsy. That is, the seizures are a symptom of a disease process we've been able to identify. If we've looked and can't find the cause, then we call it idiopathic (or primary) epilepsy. The term idiopathic simply means that we don't know the cause. It may be that the cause has escaped our attention; for example, a stroke that is too small to detect with routine brain scans or damage that occurred during whelping.

Many of the idiopathic epileptics have inherited epilepsy: epilepsy caused by a mutation in a specific gene which they inherited from their parents. Dogs with idiopathic epilepsy frequently begin seizing at between one and three years of age, and certain breeds are predisposed to develop epilepsy. A few breeds have proven hereditary epilepsy, while in most it is just a strong suspicion. One of the goals of the Canine Epilepsy Project is to identify genes responsible for epilepsy in dogs. This will allow us to positively diagnose the hereditary form and take steps to decrease the incidence of epilepsy in dogs.

How common is epilepsy?

Epilepsy is one of the most common neurologic diseases in dogs, but no one knows for sure just how common it is. Some studies estimate up to 4% of all dogs are affected. In some breeds, the incidence may be higher and some families may have up to 14% epileptics. Epilepsy occurs less frequently in cats and other pets, presumably because they do not have a hereditary form of the disease.

What determines when my pet will have seizures?

No one knows what it is that determines when an epileptic will have seizures. The only thing we can predict about epilepsy is that it's unpredictable. Some pets appear to have seizures very regularly, while in others, the seizures appear to be precipitated by specific events such as stress, or changes in the weather. However, when we try to use what's happened in the past to predict when the next seizure may occur, we usually aren't very successful. For many epileptics, there is no pattern to their seizures.

How do we diagnose idiopathic epilepsy?

Minimum work-up for an epileptic
History Your description of the character and timing of the episodes, relation to exercise, feeding, etc.
Helps your veterinarian determine if this is indeed a seizure and what type. May provide clues to the cause
Physical
examination
Evaluation of the heart, lungs, abdomen, gum color, etc.
Provide clues to diseases which could cause seizures or complicate treatment
Neurologic
examination
Evaluation of behavior, coordination, reflexes and nerve functions
Provide clues to disease of the nervous system which may be causing the seizures
Complete blood count (CBC), routine serum chemistry profile, and urine analysis (UA)
Blood and urine samples are taken and analyzed
Rules out metabolic causes of seizures and provides baseline data to monitor effects of medication
Bile acids assay or ammonia tolerance test
Usually, the pet is fasted and two blood samples are taken
Rules out liver problems and provides baseline data to monitor effects of medication
Thyroid function tests
Blood samples analyzed for T4 and TSH levels
Optional, but would rule out thyroid disease as a cause
Idiopathic epilepsy is a diagnosis by elimination. That is, we look for other causes of seizures and if we can't find any, we make the diagnosis of idiopathic epilepsy. How aggressively we search for an underlying cause is a matter of clinical judgement. We always recommend a minimum work-up for any dog having seizures. This will provide us with clues to a possible underlying disease and provide the baseline from which to watch for potential side effects of antiepileptic drugs.

Since your veterinarian may not witness one of your pet's seizures, they are very dependant upon your description of the episode. This will help them decide whether these events are indeed seizures. Other problems such as fainting or dizzy spells can also come and go like seizures and may look similar to the untrained eye. Thus, your veterinarian will need a clear description of what you observe during the episode to help make that distinction. They will also be determining what type of seizure your pet is experiencing. Write down a description of what you saw as soon as possible after the episode. If you can, make a videotape of the episode to show your veterinarian or the neurologist.

In order to rule out some diseases, we would need further tests. If the animal is outside the 1-3 year old range when idiopathic epilepsy typically starts, or has any abnormalities on examination that hint of a cause, we strongly recommend such testing. Your veterinarian may refer you to a neurologist for some of these tests. Even if an animal is within the "idiopathic epilepsy" age range, we can't be sure it's idiopathic unless we perform the full compliment of tests. One study (Podell 1995) showed that over 1/3 of the dogs between 1 and 5 years of age had an identifiable cause for the seizures. Thus we can make a case for aggressive testing in any epileptic dog, but need to weigh the additional cost involved into the equation.

Other tests that may be recommended
(may require referral to a neurologist)
MRI or CT brain scan Evaluate the structure of the brain; requires anesthesia
Rules out diseases such as brain tumors which would need to be treated directly
Spinal tap
Spinal fluid is collected and analyzed; requires anesthesia
Looks for infectious diseases and provides clues to other brain diseases
Antibody titers
Blood and/or spinal fluid is analyzed for antibodies
Identifies specific cause of an infection
Toxin tests
Blood or other sample is tested for the presence of a toxin
Tells if a specific toxin is present, but usually need a clue to what toxin to look for from the history or other test
Other laboratory tests
Advanced tests on blood, urine, or spinal fluid
Follows clues suggested by routine tests
Electroencephalogram (EEG)
Recording of brain wave to look for the electrical storm
Allows definitive diagnosis, but can be non-diagnostic
The electroencephalogram (EEG) is a useful tool in diagnosing epilepsy, but has serious drawbacks in animals. When we see abnormalities in the EEG, that tells us this is indeed a seizure and may help us pinpoint the source. The trouble is, those EEG a