General Information on Seizures
What is Primary Epilepsy?
Primary epilepsy, also known as primary epilepsy, is a recurrent seizure disorder that has no identifiable cause and is believed to be inherited in many breeds. Affected animals may be genetically predisposed for a lower seizure threshold. The most common age to develop Primary epilepsy is between 1-5 years of age. There is extensive information online regarding Primary epilepsy located at http://www.canine-epilepsy.net
What is a Seizure?
A seizure is a transitory disturbance in brain function due to abnormal electrical discharges from brain cells. Other common names for a seizure are convulsion, fit or ictus. There are two basic categories of seizures. Generalized seizures are more common and involve the body symmetrically. They are characterized by the animal falling, losing consciousness, paddling, jerking the limbs, urinating, defecating, salivating and demonstrating chewing motions with their mouth. Focal, or partial, seizures involve only a localized area of the brain and therefore produce focal signs including fly biting, facial twitches, head turning and disturbing alterations in behavior. The postictal period follows the seizure activity and is a time of abnormal behavior including signs of confusion, disorientation, restlessness, aggression or temporary blindness. The postictal period may last minutes to hours.
How Will Epilepsy Affect My Pet’s Life?
Epileptic pets are normal between seizures and generally will be expected to live a normal life span if the seizures are well controlled with medications. A well controlled epileptic can be expected to seizure less than once per month. Occasionally side effects from the medications may affect a pet’s life span. Due to the likely genetic link, epileptic pets should not be bred, and females especially should be spayed because the hormonal changes associated with the heat cycle lower the pet’s seizure threshold. Epileptic pets can be expected to experience seizures at home, but your veterinarian does not need to be notified of each seizure, rather by maintaining an accurate seizure log you can notify your veterinarian if the frequency, intensity or duration of the seizures increases. It is very important to have blood work performed at least every 12 months to monitor your pet while on antiepileptic medications.
What Should You Do If Your Pet Seizures?
Watching your pet experience a seizure can be very disturbing for an owner. The best thing you can do is to remain calm and note the time the seizure begins. Make sure your pet is on the floor so they can not fall during the seizure. Remove furniture from the immediate area and protect your pet from water, stairs, children and other pets. Animals are not at risk of swallowing their tongues; do not reach into their mouths, or place items in their mouths while they are having a seizure because you may be accidentally bitten. If you are driving when your pet begins to experience a seizure, safely pull off the road and protect your pet from falling off the car seat or becoming entangled in the seatbelt. Time the length of the seizure and record in your seizure log the date, length and description of the seizure. Seizures normally last from a couple of seconds to a couple of minutes. If the seizure lasts for longer than 3-5 minutes or if there are multiple seizures in one day contact your veterinarian or emergency care facility. Following the seizure your pet will experience a postictal period where they might appear confused, scared or even blind. During this period keep your pet protected from water, furniture, children and other pets. By maintaining an accurate seizure log you can give your veterinarian helpful information that can let them determine if the seizures
How is Primary Epilepsy Diagnosed?
primary epilepsy is diagnosed by excluding all other causes for the seizures. A thorough patient history can rule out the possibility of toxin exposure and blood work can rule out systemic diseases. Advanced imaging of the brain, done by a CT scan or MRI, is needed to rule out brain malformations, neoplasia, vascular accident, inflammation, or hydrocephalus which could be the source of the seizures. Following a normal brain scan, a spinal tap is performed to rule out any infectious or inflammatory cause for seizures. When all tests have been performed with no abnormalities noted, then a diagnosis of Primary epilepsy can be made.
How is Primary Epilepsy Managed?
There is no cure for primary epilepsy, however there are several antiepileptic medications available that can help control the frequency and intensity of the seizures. These medications come with potential side effects and need to be properly administered by the owner and monitored by a veterinarian. The most frequently used medications include phenobarbital and potassium bromide. Potassium bromide may be prescribed in addition to phenobarbital or alone. Diazepam may be prescribed to patients who have clusters of seizures, or to cats. These medications will likely need to be given for the life of the pet.
Phenobarbital is effective in controlling seizures in the majority of patients. Your pet may be lethargic or incoordinated for a short period of time after starting the medication. Phenobarbital blood levels should be measured 2-3 weeks after starting the medication. Common side effects include increased appetite, thirst and urination. However, your pet should not be fed more as this will predispose them to excessive weight gain. Phenobarbital can also cause liver toxicity and problems with the development of blood cells; for these reasons, we recommend that your pet have a complete blood count and chemistry profile every 6-12 months. Missed doses or a sudden discontinuation of phenobarbital may precipitate severe seizures.
Potassium Bromide (KBr)
KBr may be prescribed to help control seizures. KBr may cause stomach irritation and should be given with food. Side effects include sedation and increased appetite, thirst and urination. If your dog refuses to eat or vomits after being given KBr or if excessive sedation occurs you should contact your veterinarian. The level of KBr in the body is dependent on the salt content of the diet, making it important that your pet stay on a constant diet. If a diet change is indicated, it should be done gradually and KBr levels should be monitored during and after the change.
Diazepam is quickly eliminated by a dog’s system when administered orally making it an ineffective medication to use for daily seizure control. However it is longer lasting in cats, and therefore maybe used as an oral antiepileptic medication for them. Diazepam maybe prescribed rectally for patients who experience cluster seizures (multiple seizures in a day) or status epilepticus (prolonged seizure activity longer than 5 minutes). Diazepam is administered rectally to try and break the cycle of seizure activity. If this medication is prescribed for your pet you will be instructed on how and when to administer it. Diazepam is inactivated by light and adheres to plastic, and therefore should be stored in the vial in which it is dispensed until used.
Other Antiepileptic Medications
When seizure frequency is not adequately controlled by phenobarbital or KBr, or unacceptable side effects occur, alternative medications can be used to attempt to manage the seizures more effectively. They include Felbamate (Felbatol), gabapentin (Neurontin), levetiracetam (Keppra) or zonisamide (Zonegran). These medications are often more expensive and their efficacy has not been tested as objectively yet. We are still learning about all the side effects and beneficial effects of these drugs.
If you have further questions, feel free to discuss them with your veterinarian or the Neurology Service.
The Neurology department at NCSU-VTH is constantly researching primary epilepsy. Please visit the Neurology website at: http://cvm.ncsu.edu/vhc/tc/clinical_services/neuro/index.html to read more!