Epilepsy In Your Pet
Seizures In Dogs And Cats
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Or Ask Me For This 2014 Treatment Review
Ron Hines DVM PhD
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Never use supermarket "flea-drops" (permethrin products, spot-on) on cats. Even exposure of your cat to canine pets in the same household that have those products applied to them has been enough to cause severe seizures in felines. Read about the problem here
Epilepsy is a disease in which your pet is subject to recurrent seizures or convulsions. It is quite similar to the 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.
Veterinarians 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 equipment is becoming more an more sophisticated so it is probably only a matter of time until we will be able to see what the physical or chemical problem actually is in these pets.
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. Seizures also occur more frequently in staffordshire bull terriers than in many breeds. But those seizures are often related to a specific neuro-metabolic disorder seen in this breed. (ref)
In cats, I see the common (idiopathic) form most frequently in Persians and Siamese.
If your dog has common epilepsy, it is very likely that it inherited it from its parents. Epilepsy is known to effect specific dog and cat blood-lines more frequently than others. In dogs, veterinarians think that it is often a genetic disease, Usually, a parent or a close relative of your pet also had epilepsy. The causes in cats are less clear. In young adult dogs, the majority of epilepsy is the non-progressive, idiopathic, form.
In cats however, only about a third of the cases are the non-progressive, idiopathic form. In cats, brain inflammations (encephalitis), exposure to toxic substances, traumatic injuries, abnormal body metabolism and brain tumors account for the other two-thirds. Your cat is more likely to be among the fortunate third if it is less than 3.5 years of age when the problem first begins and is also negative for Feline AIDS and Feline leukemia.
What Is Happening To My Pet When It Has A Seizure ?
It is very frightening to watch your pet experience a seizure. But you need to keep in mind that during the seizure your pet is not in pain. The pet may vocalize and thrash around, but it does not experience painful sensations. It is just before and after the seizure that your pet will be frightened and need your reassurance.
During an epileptic seizure random electrical 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 a complete epileptic seizure the pet looses consciousness and has no memory of the event ever occurring.
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 petit 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. In this respect, a typical epileptic seizure is much like a single snowball setting of a great avalanche. These abnormal electrical signals constitute a seizure. If the seizure affects the whole body, the pet looses consciousness. If it is a partial seizure, the pet 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 inflamed or when brain tumors are present.
Things outside the brain can cause secondary epilepsy too. Things like overheating (hyperthermia), low blood glucose (hypoglycemia) , intestinal inflammation or liver and kidney failure. Poisons and toxic chemicals can also cause seizures. For example, certain flame retardant chemicals, when eaten, have the ability to cause seizures. (ref). Thiamine-deficient diets have also caused seizures in cats. (ref).
What About Epilepsy In Cats ?
Idiopathic epilepsy is much less common in cats than in dogs. As I mentioned earlier, unlike dogs, cats often develop seizures because of some progressive, acquired brain disease. Because many of these underlying causes increase in severity over time, the long-term prognosis (outlook) for epileptic cats is not nearly as good as it is for dogs. But even in these cats, your veterinarian can often control these seizures for a time.
I have seen more idiopathic or common epilepsy in pure-bred than in randomly-bred housecats.
Another common cause of epileptiform (epileptic-like) seizures in cats is infection with the virus of feline infectious peritonitis ("the dry form" of FIP). Another rarer cause is infection with toxoplasmosis. Increases in the pressure within your pet's 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 (like baylisascaris ) account for almost all of the other cases of seizures in cats.
When In Life Does Epilepsy Usually Start And What Does A Real Seizure Look Like ?
Most pets have their first seizures between 1 and 5 five years of age. During a complete seizure, the pet falls on its side with its legs outstretched and it’s back arched. Partial seizures have much more variable signs. Most pets maintain their legs rigidly extended but some paddle as if they were running. Pets may whine - although they are not in pain.
These pets often void their bowels and bladder during their convulsions. 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. Those pets do remain consciousness but often mentally impaired.
Focal simple seizures or partial epilepsy are often misinterpreted by owners as just a periodic 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 thought 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, no 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, not your veterinarian, can decide if the number and severity of seizures your pet experiences, justify the risks of continuous, lifetime medication.
Stages Of A Seizure
A seizure event of epilepsy can be broken down into three distinct stages. It is a very ancient disease, so the event has been divided in many ways using many confusing terms.
The first stage is called the prodromal, or warning stage. This stage usually lasts several minutes but can last much longer. During this stage, the pet may have changes in its mood and behavior and may appear anxious. Some common signs are restlessness, wandering, pacing, licking, trembling and vomiting. In epileptic people, therapy dogs have been trained to warn their owners during this stage that a seizure is eminent.
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, or appear blind or deaf.
What Tests Will My Veterinarian Run To Confirm That My Pet Has Epilepsy ?
Your veterinarian will want to begin with a complete blood chemistry panel on your pet as well as a urinalysis on the pet's urine. If your pet has simple or idiopathic epilepsy, these tests will probably all come back normal. (T4 could be low if the pet is already taking phenobarbital [ref]) If your veterinarian is reasonably certain of the diagnosis at that point, the vet might begin the pet on an anti-epileptic medication. When the diagnosis is not that evident, the vet can go on to order more specialized tests, such as an MRI, CT scan or even a cerebrospinal tap (vets generally obtain that fluid higher up at the base of the pet's skull) - usually in that order - until the diagnosis is made.
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 and more serious.
Seizures that last longer than 5 minutes can become medical emergencies if these pets have trouble breathing. Have your veterinarian provide you with an emergency dose of injectable diazepam (Valium) if you pet has experienced such seizures in the past. Give nothing by mouth.
My first concern for my clients is that they 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.
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 in opposite directions - to force the mouth open. Your pet doesn't recognize you during seizures and its jaws can clench forcefully on your hands.
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, cool 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 pet owners have been instructed in how to insert a diazepam tablet rectally to break a seizure. (I have not attempted that procedure myself so I do not know if it is effective.) Do not give tablets by mouth while a pet is having a seizure or subsequent to a seizure.
How Soon Should I Start To Think About Continuous Medications For My Pet ?
This is a difficult question to answer. I generally suggest that dogs and cats receive anti-seizure medications if they have had 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. How frequently, if ever, that owners can tolerate the sight of seizure behavior in their pets is also a major factor for many pet owners.
What Medications Are Available To Treat Epilepsy In Pets ?
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 or if a combination of medications is used. Phenobarbital works well in both dogs and cats. Cats do not seem as prone as dogs to liver damage while on this drug, but they do tend to gain weight.
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 this liver damage. Some owners give their epileptic pets milk thistle to try to protect the liver. (unfortunately, the only recent scientific study of milk thistle's "active" ingredient, silymarin, found it of no value in humans with one form of chronic hepatitis ref. Silymarin is one of the two "active" ingredients in Denamarin) Phenobarbital is an old medicine. Despite its numerous side effects, it has been used to control seizures in humans since 1912. You can read the NIH product description here.
Primadone (Mysoline, Mylepsin, etc.)
The effects and side effects of primadone are the same as phenobarbital. In your pet's body, much of the primadone 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.
This drug is compounded by a number of special order veterinary pharmacies (It should be approved by the FDA as a prepackaged product in 2012) It can be used to lower the amount of phenobarbital your pet is given to hopefully decrease the likelihood of liver damage. Dogs taking potassium bromide should receive it with food. They need to be careful with the salt levels in their diet and whenever their brand of dog food is changed. Their T4 levels and serum bromide concentrations need to be periodically monitored. The most common side effects of this drug are behavioral changes, muscular twitching and staggered gait. You can read in detail about these side effects and others here. Most veterinarians rely on phenobarbital to get your pet's seizures under control and then add potassium bromide as a second line medication to keep the pets phenobarbital dose as low as possible. It is rarely used at this time as the primary seizure-control medication. (ref).
Cats do not respond as well to potassium bromide as dogs do. The use of this medication in cats has also been frequently associated with a type of lung inflammation called pneumonitis. (ref) When pneumonitis occurs, it can produce signs quite similar to feline asthma.
This drug alone is only good to end dangerous long-lasting seizures until another medicine can take effect. In dogs and cats, it is quite good at breaking a persistent, dangerous seizure; but when it is given over longer periods of time the body becomes resistant to its effects. It can be an effective "add-on" medication for epileptic cats because it seems to persist longer in the blood stream of feline than canine patients.
(Some newer drugs used in human epilepsy show promise in dogs.
These include clorazepate, felbamate, gabapentin, levetiracetam
and zonisamide. However, the dog's Liver
enzymes need to be monitored
closely, particularly if the dog receives zonisamide (ref)
Veterinarians have less experience using these newer anti-seizure medications than phenobarbital or potassium bromide. These newer medications were developed for human use and it is yet unclear what their long-term effects might be in dogs and cats. Veterinarians rarely use them when a pet's seizures can be adequately controlled using these two better-known, traditional medications. So use the newer ones all with caution and with frequent monitoring of your pet's blood blood chemistry. Periodic monitoring of all anti-seizure medication serum blood levels as well as their effects on your pet's liver and kidney function is always a good idea.
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 seem work the same. Because dogs vary greatly in how they absorb this drug, blood levels should be frequently checked. Side effects of clorazepate are sleepiness and a wobbly gait.
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.
This drug also causes little to no sedation. It is sometimes given successfully to pets to supplement to other anti-seizure medication such as phenobarbitol and bromide when they do not control seizures well enough on their own. When using Neurontin, always try to stay at the lowest possible dose. A few veterinarians have found it helpful but many have not. You can read an article on it's use here.
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.
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 , perhaps, entirely eliminated.
This medicatin works quite well in dogs and is a common alternative medication to phenobarbital in Europe. But as of 2016, it is still not available in the United States. Read about Pexion here.
Valproic Acid (Depakote®)
This medication does not work as well in dogs and cats as it does in people with epilepsy. It can be quite 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 or two seizures 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 and schedule any changes so that seizures are unlikely to occur on weekends, holidays or periods when your regular veterinarian is not likely to be available. If seizures frequently reoccur, your pet will probably need its medications for its lifetime.
Might My Pet's Diet Affect The Number and Intensity of Its Seizures ?
There is some preliminary evidence that in humans at least, a diet based primarily on meat protein and fat might be beneficial in controling epilepsy. You can read a review of that information here. You can read some tips on preparing all-meat or high meat diets here. (I would caution you against feeding your pet any diet that contains raw meat. That is because the threat of infection from contamination of these products is greatly increased when a pet has chronic health problems of any kind.)
Will Idiopathic Epilepsy Shorten My Dog's Life ?
Typically, idiopathic epilepsy will not shorten your dog's life.
Contact Dr. Hines
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