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Ron Hines DVM PhD
Epilepsy is a disease in which your pet is subject to recurrent seizures or convulsions. It is similar to epilepsy that occurs in people. Seizures in our pets can have a number of causes - Not all seizures or convulsions are due to common epilepsy. Idiopathic means that we do not know the cause. Once we have eliminated all possible other causes, we are left with a diagnosis of common (simple, true or idiopathic) epilepsy. We can not find physical problems in pets that have idiopathic epilepsy when they are not in the process of a seizure. All the blood tests, all the x-rays and examinations come back normal. But medical diagnostic equiment is becoming more an more sophisticated so it is only a matter of time until we will be able to see what the physical or chemical problem actually is. What Pets Get Epilepsy? Any breed of dog or cat can develop epilepsy. But Golden Retrievers, Beagles, Cocker Spaniels, Dachshunds, German Shepherds, Irish Setters, Schnauzers, and Huskies seem to have the problem a bit more than other breeds. I see the common form most frequently in Persian and Siamese cats. If your pet has common epilepsy, it is very likely that it inherited it from its parents. Epilepsy effects blood-lines of dogs and cats. It is a genetic disease. Usually, a parent or close relative of your pet also had epilepsy. What Happens To My Pet When It Has A Seizure? It is very frightening to watch your pet experience a seizure. You need to keep in mind that during the seizure your pet is not in pain. The pet may vocalize and thrash around, but they do not experience painful sensations. But just before and after the seizure they are frightened and need your reassurance. During an epileptic seizure random impulses are sent from the nerve cells of your pet's brain to muscles throughout its body. In idiopathic epilepsy, the source of these abnormal brain impulses are small areas of abnormal or damaged brain tissue. During an epileptic seizure the pet looses consciousness. Epileptic seizures are a bit like an electrical storm. Their primary origin within cerebral cortex of the brain and the target tissues of their nerve cell impulses define the type epilepsy that occurs. Seizures that put the whole body into severe muscle contractions, are called grand mal seizures. Seizures that are less severe and only affect a few muscle groups are called petite mal seizures. Status epilepticus is a term used for severe seizures that occur again and again with little or no rest between convulsions. These can be fatal. During a seizure, these tiny areas begin sending out electrical impulses that are received by the nerve cells that surround them. This results in a chain reaction in which the surrounding nerve cells are stimulated to fire off a shower of signals of their own to various muscles of the body. These abnormal electrical signals constitute a seizure. If the seizure affects the whole body, the pet looses consciousness. If it is a partial seizure, it may realize that something is occurring. In cases if idiopathic epilepsy, nothing can be found that is physically wrong with the brain. Secondary Epilepsy and Seizures: When a defect within the brain can be identified as the source of the abnormal impulses, we call the condition symptomatic or secondary epilepsy. Secondary seizures often occur when pressure within the brain is too high (intracranial pressure). They can also occur when the brain is inflammmed or when brain tumors are present. Things outside the brain can cause secondary epilepsy also. Things like overheating (hyperthermia), low blood glucose (hypoglycemia) , intestinal inflammation or liver and kidney failure. Poisons can also cause seizures. Epilepsy In Cats Idiopathic epilepsy is over 20 times as common in dogs as in cats. Unlike dogs, cats often have seizures because of acquired brain disease. Because many of these causes are progressive, the long-term prognosis for epileptic cats is not nearly as good as it is for dogs. But often these seizures can be controlled too. For more information on epilepsy in cats, try this Yahoo Group . Purebred cats are more susceptible to epilepsy than randomly bred cats. But they are much more likely to have the treatable idiopathic form. One common cause of epileptiform seizures in cats is infection with the virus of feline infectious peritonitis (FIP). Another cause is infection with toxoplasmosis. Increases in pressure within the brain, liver and kidney disease, low blood sugar, brain tumors, vitamin B-1 deficiency, feline immunodeficiency virus (feline AIDS), rabies, insecticides, antifreeze and migrating parasites account for most of the other cases of non-idiopathic epilepsy in cats. When In Life Does Epilepsy Usually Start And What Does It Look Like? Most pets have their first seizures between 1 and 5 five years of age. During a seizure, the pet falls on its side with its legs outstretched and it’s back arched. Most pets maintain their legs rigidly extended but some paddle as if they were running. Pets may whine - although they are not in pain. They often void their bowels and bladder. Their jaws are clenched during the first phase of the seizure. If only a portion of the body is affected the seizure is called a focal simple seizure or a partial seizure. These pets remain consciousness Focal simple seizures or partial epilepsy are often misinterpreted as just quirky behavior. Sometimes muscles of the face just go into a jerky motion. Sometimes the pets appear to be snapping at invisible flies or chewing gum or running round and round in circles. Frontal Lobe Epilepsy: Some seizures affect portions of the pet's brain that control thought rather than motion. When an area of the brain that controls the conscious process is affected the seizure is called a psychomotor seizure or hallucination. In humans this form of seizure is called frontal lobe epilepsy. During this altered period of consciousness your pet may show fear, aggression, hyperactivity, or repetitive nonsensical behavior. Some pets hear imaginary noises. Your pet may bite or snap at you if you disturb it during one of these episodes. Because so many areas of the brain can give rise to epileptic seizures, not two pets exhibit exactly the same signs. In some instances seizures will be a one-time episode never to occur again. In other pets the problem reoccurs at regular intervals of from every several days to several times a year. Common medications to treat epilepsy can damage your pet's liver over time. Only you, can decide if the number and severity of seizures your pet has, justify the risks of continuous medication. Stages Of A Seizure: A seizure event of epilepsy can be broken down into three distinct stages. It is an ancient disease, so the event has been divided in many ways using many terms. The first stage is called the prodromal, or warning stage. This stage usually lasts several minutes but can be much longer. During this stage, the pet may have changes in mood and behavior. Some common signs are restlessness, wandering, pacing, licking, trembling and vomiting. In people with epilepsy, dogs have been trained to warn their owners during this stage that a seizure is eminent. The
next stage is called the ictus or ictical stage. This is
the time of the seizure itself when the body is subject to uncontrolled
movement and thrashing. During this stage, the pet is unconscious.
Paddling or swimming movements, clenched teeth, and arched back
are common during this stage. In cases where partial seizures occur,
the pet may run in circles, and appear blind or deaf. What Should I Do During The Seizure? When a seizure occurs, owners tend to over-react. Their first inclination is to rush the pet to an emergency veterinary center. Luckily, most epileptic seizures last only a few minutes. One to three minute seizures are most common. Those that last five to ten minutes are less common. Those that last longer than 5 minutes can become medical emergencies if these pets may have trouble breathing. Your first concern is NOT TO BE BITTEN. If your pet or a neighbor’s pet develops a seizure begin by placing the pet’s head on a soft folded towel or pillow. You may carry the pet in a blanket to a tiled area so as not to soil the carpet or rug. Then remove all objects that surround the pet so it will not injure itself. Do not put your hands into the pet’s mouth or you are very likely to be bitten. It is quite rare for a dog to “swallow” its tongue but if the pet should turn bluish you can use an inverted spoon to manipulate the tongue. If this is not sufficient and the dog is still having difficulty breathing open the mouth by passing two towels through the mouth and pulling on them – one up, one down - to force the mouth open. Your pet doesn't recognize you during seizures - DON'T GET BITTEN ! You can gently stroke and speak calmly and softly to your pet. But the pet will not know you are present until the seizure begins to subside. Keep the room darkened and keep other family members away. You can already position some paper towels and warm soapy water on a wash stand beyond the pet’s reach to help clean up any mess. Owners that have experienced "break-through" seizures in their pets often have injectable diazepam issued to them to break seizures. In emergencies, some have been instructed in how to insert a diazepam tablet rectally to break a seizure. Do not give tablets by mouth while a pet is having a seizure. How Soon Should I Start To Think About Medicating My Pet? This is a difficult question to answer. I generally suggest that dogs and cats receive anti-seizure medications if they have two or more seizures within an 8-week period or two or more cluster seizures within a 12-week period. Dogs and cats that show unusually severe ictal or post ictal periods should also begin medication. It is a decision best left up to your veterinarain. What Medications Are Used To Treat Epilepsy? Phenobarbital:
Phenobarbital is the most commonly used drug to treat epilepsy in
dogs and cats. The side effects of phenobarbital are sedation, increased appetite, weight gain, increased thirst and urination and harm to the liver over time. These problems can be minimized if the dose is closely regulated. Pets on Phenobarbital need to have their liver enzymes tested periodically to check for possible liver damage. Combining phenobarbital with a second drug, such as Potassium bromide, may protect your pet from liver damage. Some owners give their epileptic pets milk thistle to try to protect the liver. Primadone (Mysoline, Mylepsin, etc.) The effects and side effects of primadone are the same as phenobarbital. In your pet's body, much of the primaedone is converted to phenobarbital which accounts for most or all of its anti seizure effects. Phenytoin (Dilantin, diphenylhydantoin) This drug rarely controls seizures on its own. It should never be given to cats. It can also be toxic to the liver of dogs. Potassium Bromide This drug is compounded by a number of special order pharmacies . It can be used to lower the amount of phenobarbital your pet is given to decrease the likelihood of liver damage. Dogs taking this drug need to be careful with salt levels in their diet and whenever their brand of dog food is changed Valium (diazepam) This drug is only good to end dangerous long-lasting seizures until another medicine can take effect. It is quite good at breaking seizures but when it is given over longer periods of time the body becomes resistant to its effects.
(Some newer drugs used in human epilepsy show promise in dogs.
These include clorazepate, felbamate, gabapentin, levetiracetam
and zonisamide.
Clorazepate (Tranxene®) This drug can be used in conjunction with phenobarbital. It is moderately effective but serum levels of the drug need to be monitored every 4-6 months as they tend to drift downwards. Clorazepate is similar in structure to diazepam (Valium) and like diazepam, it works well in emergencies. It is available in regular and time-release form. In dogs, both forms work the same. Because dogs vary greatly in how they absorb the drug, blood levels should be frequently checked. Side effects of clorazepate are sleepiness and a wobbly gait. Felbamate (Felbatol®) The primary advantage of felbamate is that it does not cause drowsiness. It is often given along with phenobarbital to lower the phenobarbital dose. The toxicity of this drug is very low but it has to be given several times a day. Blood samples should occasionally be taken to check for liver toxicity and bone marrow suppression, which are uncommon side effects. Gabapentin (Neurontin®) This drug also causes little to no sedation. It is sometimes given to pets to supplement to other anti-seizure medication such as phenobarbitol and bromide. When using Neurontin, try to stay at the lowest possible dose. A few veterinarians have found it helpful but many have not. Levetiracetam (Keppra®) This medication has been used in dogs in combination with phenobarbital and potassium bromide to lower the daily dose of phenobarbital received and in cases where phenobarbital was not able to control the seizures alone. The drug appears quite safe. Rare side effects in dogs include stiff wobbly gait, vomiting and salivation. It's cost is high and it requires frequent dosing. Zonisamide (Zonegran®) This drug is sometimes effective in blocking seizures and has few side effects that we know of. When it is used, it is usually an add-on therapy for dogs already receiving phenobarbital. When this drug is used, the phenobarbital dosage can sometimes be drastically reduced or entirely eliminated. Valproic Acid (Depakote®) This medication does not work as well in dogs and cats as it does in people with epilepsy. It can be toxic to cats. It is occasionally used to supplement other anti-seizure medications in pets. It can cause the pet to loose hair and it can be toxic to the liver. It can cause drowsiness, sedation, nausea and vomiting. It is best given with food. Can I Ever Stop Giving My Pet Medications? Pets that were put on long term phenobarbital because their pet had one seizure probably shouldn't be on it at all. But if your pet had multiple seizures that were determined to be idiopathic epilepsy, I suggest not attempting to lower or discontinue medications until your pet has been free of seizures for a year. Do not change or discontinue medications without the knowledge of your veterinarian. If a seizure reoccurs, your pet will need its medications for life. |
