Pet Seizures and Epilepsy
OVERVIEW OF SEIZURES:
We all think we know what happens when a seizure occurs. After all, we've seen actors pretend to have seizures on television. But the reality of your pet having a seizure is much more frightening. Out of the blue, your pet may start to drool, stare into space, and pace. Suddenly the poor animal falls to the ground, his body racked by convulsions, as he involuntarily passes urine and stool. When the seizure ends, he remains confused, nervous, and disoriented, and may even lose his vision. The bottom line is that seizures are terrifying for the owner and potentially very dangerous for the pet. Not only can the pet injure himself during the seizure, but the seizure itself can actually kill the animal. Understanding the cause, signs, and treatment for seizures can help owners deal with this medical problem.
The first concept to understand is that seizures are not a disease themselves. Instead, they are a sign of a problem. A seizure is simply the body's muscles responding to excess activity of the neurons in the brain. Some type of neurological miscommunication allows these excitatory nerves to 'fire' without coordination with inhibitory neurons that should keep them resting quietly. These excitatory nerves fire and stimulate whichever muscles and organs they communicate with. The extent and location of the neuronal hyperactivity determines which part of the body is affected by the seizure and how severe the seizure is. Some minor seizures affect only a few muscles; others affect the entire body. The bottom line is that a seizure is a response to uncontrolled bursts of neurological activity in the brain.
So a seizure is a disease sign. It tells us that the brain is having some type of problem. Unfortunately, the seizure does not tell us what is causing the problem. Anything that allows an abnormal burst of electrical activity in the brain can lead to a seizure. The list of possible causes is extremely long, but it is important to try to find the reason for a pet's seizures. First, some of the underlying causes of seizures can be cured with treatment, therefore preventing further seizures. Second, some causes must be treated because they themselves threaten the animal's life. Third, some of the causes cannot be eliminated, and the best one can hope for is to control and prevent the seizures with anticonvulsant medication. Finally, some of the problems must be treated, in that anticonvulsant therapy alone will not be successful. For example, seizures in young puppies may be caused by low blood sugar, which can and must be treated. If the low blood sugar is not controlled, the puppy will not respond to anticonvulsant therapy and may die. So diagnosing the cause of the seizures is often critical for successful treatment.
CAUSES OF SEIZURES:
Your veterinarian will use several tools to help identify the cause of the seizures. The animal's age, breed, and physical examination provide valuable clues, as does the history of the seizure episodes' duration and frequency. The age that the seizures began and the pattern of their occurrence also supply important information. The veterinarian will want to do laboratory tests, including blood work and a urinalysis. Additional tests for specific diseases may be needed. Modern medical technology also allows veterinarians to use MRI scans of the brain to locate problems. Finally, analysis of the cerebral spinal fluid (CSF) may be needed to look for abnormal cells in the fluid that bathes the brain and spinal cord.
Treatment of the underlying problem depends entirely on the cause. Some therapies include treatment of infections with appropriate medications, fluids to correct electrolyte and sugar abnormalities, the use of antidotes, anti-inflammatory medications, or special diets, corrective surgery, tumor removal, radiation, and chemotherapy. Because one cannot predict the exact cause, an exact treatment regime cannot be designed until the diagnosis is made.
The differential diagnosis list for the cause of seizures is very long. Common underlying causes are metabolic problems such as low blood sugar, high blood sugar, kidney failure, liver failure, low blood levels of calcium, and low thyroid function. In addition, toxins, such as antifreeze, snail bait, and lead can lead to seizures. So can infections, such as canine distemper, Rocky Mountain spotted fever, and toxoplasmosis. Some seizures are caused by congenital malformations, such as hydrocephalus of newborns. Anything that changes the structure of the brain can lead to seizures, so tumors and trauma to the brain are potential causes. Even lack of blood supply to the brain, such as that seen with anemia and heart disease, can lead to seizures. The list goes on and on, encompassing any problem that impacts the body and the brain. Even using all available diagnostics, it can be difficult to find the cause of a seizure. Many times all the tests are normal, yet the pet continues to have seizures. Those that have repeated seizures with no other discernable abnormalities are diagnosed as epileptics.
UNKNOWN CAUSE - EPILEPSY:
The most common cause of seizures is epilepsy. Epilepsy basically means that the animal has recurring seizures. There are no specific tests for this illness. Instead, epilepsy is considered a diagnosis of exclusion. All other causes are eliminated, or excluded, leaving only the diagnosis of epilepsy. In pets with epilepsy, the structure of the brain is normal and there are no underlying discernable diseases, yet the animal continues to have abnormal brain function which leads to seizures. There is not way to cure the problem because an underlying problem cannot be found and cured. Instead, treatment is aimed at limiting the number, severity, and length of the convulsions. The use of anticonvulsant medication allows the pet to lead a more comfortable, safer life. Even though epilepsy is diagnosed by eliminating other causes, the diagnosis must still be made to ensure the best treatment for a pet. Do not assume that a pet has epilepsy - the other causes must first be excluded.
You may see epilepsy listed as idiopathic epilepsy. Idiopathic simply means that the epilepsy does not have a known cause. Idiopathic epilepsy is actually pretty common. Between 0.5% and 2% of all dogs are epileptics. More importantly, between 40% and 80% of all dogs that have seizures will be diagnosed as epileptics. This means that most dogs will end up with this diagnosis. Epilepsy has a genetic component and is seen in several common breeds, including shepherds, beagles, border collies, shelties, boxers, retrievers, poodles, huskies, and some terriers. It makes sense that a problem with a genetic basis would be this common, considering the popularity of the breeds that carry the trait. Most dogs that have idiopathic epilepsy start their seizures between 6 months and 5 years of age and often get worse over time. Those that start younger in life usually have more severe problems. Anticonvulsant therapy is typically started once a second seizure is noticed or if the animal has status epilepticus or cluster seizures.
TYPES OF SEIZURES:
Understanding the actual seizure itself will allow you to help your pet during a seizure and to decide if emergency care is needed. Basically, there are different types and stages of seizures. Partial seizures are a type that impact only part of the body and start in one local area. They usually do not require immediate, emergency care. The pet remains conscious, although mental acuity may be altered. These partial seizures may be as minor as a twitching paw or may eventually generalize to impact the entire body.
The type of seizures called general seizures affect the entire body. The pet loses consciousness. In a general, petit mal seizure, the animal does not have convulsions, but does lose consciousness, the facial muscles may twitch, and the animal may appear to be staring into space. These are much less common than general, grand mal seizures. A grand mal seizure is the type one thinks of as seen on TV, and is the most common type seen in cats and dogs. During a grand mal seizure, the animal loses consciousness, involuntarily urinates, defecates, and salivates, and falls to the ground with intense muscle activity (convulsions). These seizures are very serious. If they last for longer than ten minutes, or if several occur in a short period of time (during which the animal does not regain consciousness), the condition is termed status epilepticus. If multiple seizures occur within 24 hours, they are termed cluster seizures. Cluster seizures and status epilepticus are life-threatening and require immediate, emergency veterinary care.
STAGES OF SEIZURES:
No matter which type of seizure occurs, they typically follow a pattern of stages. Some have a prodromal stage that can last for hours or days. During this stage the animal acts differently than is expected. Astute owners can learn to identify the prodromal stage. Immediately preceding the actual seizure is the aura. The aura tells the owner that the seizure is starting. The pet may whine, tremble, be restless, nervous, or apprehensive, or try to wander away or hide. Some pets in the aura stage seek owner comfort and attention. Some start to drool. This stage is immediately followed by the actual seizure, or ictal phase. This is the time of collapse, extreme muscle activity, thrashing of legs, drooling, loss of consciousness, crying, paddling, urination, and defecation. This stage usually lasts less than 4-5 minutes and is followed by the post-ictal phase. This is the recovery period. Most owners are unaware that the recovery phase can last minutes to days and may include increased appetite and thirst, temporary loss of vision, pacing, and disorientation. Owners that learn to recognize the stages of their pet's seizures can take steps to reduce risk to the pet. For example a pet in the prodromal stage should not be left alone and should be kept away from staircases and concrete flooring. A pet that is in the post-ictal stage may be blind and need assistance to prevent him from injuring himself.
SEEING THE VETERINARIAN:
As we've discussed, seizures are a sign of an underlying medical problem. A pet that has a seizure should be seen by the veterinarian for two reasons. First, the veterinarian will want to try to determine and treat the cause, which may be imminently life-threatening. Second, even if the cause cannot be found and eliminated, the seizures may need to be controlled with medication. Seizures that last for too long or occur too frequently can cause brain damage and be life threatening. So, if your pet has a seizure, he needs to be seen by the veterinarian.
TREATMENT AND PREVENTION OF SEIZURES:
Now you know more about seizures, but what do you do if your pet has a seizure? The first step is to stay calm and access the situation. Move the pet away from hard or sharp objects that can cause injury and keep the animal away from stairs, furniture, and hard flooring. Keep your hands out of the pet's mouth. The animal will not swallow his tongue, but a seizuring pet will bite your hand or fingers. Do not allow the animal to bang his head on a concrete floor. Next, time the seizure. If it lasts more than a few moments, or repeats after ending, seek immediate veterinary care. A seizure requires intense muscle activity and creates heat. An animal that has a prolonged seizure will experience a life-threatening rise in body temperature and may suffer permanent brain damage or organ failure. In addition, it is possible for cluster seizures or repeat seizures to go for such a long period of time that animal cannot come out of the seizure. The faster treatment is started, the more likely the animal will have a favorable response to the therapy.
If a pet is having a seizure that lasts more than a few moments, your veterinarian may need to provide emergency care. Drugs will be given intravenously to calm the seizure area in the brain and to stop the seizure. This cannot be done at home. If the seizure stops quickly, it is not an emergency, but the pet should be examined. Your veterinarian will determine if and when anticonvulsant medications should be used. A veterinarian may choose to delay therapy if a pet has a very mild seizure (lasts only moments) that does not repeat more often than every six weeks or so.
The veterinarian may choose to start therapy for those dogs that seizure more frequently, have severe seizures, or have seizures of longer duration. Be aware that the brain actually becomes sensitized to the seizure activity. This means that it becomes easier for a brain to have a seizure after one occurs. Think of it as 'learning' the pathway of the seizure. So, the more frequently a pet has a seizure, the more likely the animal is to have one again. The seizure may increase in frequency, duration, and intensity. Therefore, it is critical to follow your veterinarian's instructions regarding anti-seizure medication. The use of this medication can not only make your pet more comfortable, but also prolong his life.
The anticonvulsant medication will not 'cure' the pet. Only finding and eliminating the underlying cause can do this. Some pets with identifiable and treated underlying causes will still need to take medication. Other animals, such as those with epilepsy, do not have a discernable underlying cause and cannot be cured. The goal of medication is to reduce the frequency, severity, and duration of the seizures. A few lucky animals never experience another seizure once starting medication; most just have fewer, milder seizures that are spaced farther apart. Unfortunately, some animals are never adequately controlled and treatment becomes very difficult.
There are several anticonvulsant medications available. Your veterinarian may need to try one or more medications, or different combinations of medications, to achieve control. It may take weeks to months to achieve adequate control. The most commonly used medication for cats and dogs is a sedative called phenobarbital. This medication is given twice per day by mouth. It is important to follow your veterinarian's schedule for the use and testing of the medication. It takes about 2 weeks for the medication to reach a steady level in the blood stream, so blood tests to determine the level of the medication in the blood should be done two weeks after starting it. Blood levels should be repeated in two more weeks to make sure that the pet is maintaining the correct amount of drug in his bloodstream. Blood levels may need to be retested whenever the dose is changed. Liver tests will need to be run periodically to make sure that the pet's liver can tolerate the medication.
Another common medication is called potassium bromide. This medication can take 3-4 months to reach a steady state in the blood stream, so repeat blood tests are necessary with this medication as well. Some animals respond best to combinations of phenobarbital and potassium bromide. Some cats are treated with diazepam or combinations of phenobarbital and diazepam. There are other, less commonly used medications, such as Dilantin and Neurotonin, available through veterinary neurologists. These medications are expensive and most often less helpful than phenobarbital. Some animals have been successfully treated with acupuncture.
In addition to proper medication, there are steps you can take to help prevent seizures. First, make sure your veterinarian is aware of all medications you pet uses, including those applied to the skin. Some medications can promote seizures in pets that already suffer from them, or interfere with the anticonvulsants. Avoid insecticides, lawn treatments, cleansers, and drugs that have been linked to seizures. Finally, identify and eliminate any triggers that may over-stimulate the brain and lead to a seizure. These triggers may vary among pets and can include lights, noise (thunder), fear (a visit to the veterinarian), excitement (greeting a friend) and even vaccination. If you can identify potential triggers, you can take steps to eliminate or modify them and potentially reduce the seizures. It helps to keep a seizure diary. Record the duration, date, and severity of the seizure, along with events preceding the seizure. You may be able to identify events that stimulate a seizure and avoid them in the future.
The bottom line is that seizures are scary and potentially life threatening. Many dogs and cats will suffer from them in their lifetime. These pets can typically be helped with proper diagnosis and therapy. If your pet has a seizure, seek veterinary care. Work with your veterinarian to run the necessary tests and provide necessary therapy. With proper medication and follow-up, most pets can live a normal life interrupted by a few, unwanted seizure episodes.
Dr. Jane Leon
Consultant for Omaha Vaccine Company