Epilepsy And Seizures In Your Dog And Cat

Ron Hines DVM PhD

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Screen pets that do not improve on epilepsy/seizure medications for high ammonia and/or bile acid levels. But both can be the cause or the result of seizures (ref1, ref2)

It appears that levetiracetam is also effective when applied to the inner side of the ear as a topical cream. Read about that here

Dog owner experience with Levetiracetam (Keppra®) 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 have many causes – Not all seizures or convulsions are due to common epilepsy (less than half are). [The older your pet is when it experiences its first seizure as well as the presence of residual nerve abnormalities between seizures, decrease the likelihood that it has idiopathic or common epilepsy.] (ref)

Idiopathic just means that we do not know the cause. Once we have eliminated all other possible causes of repeating seizures, veterinarians are left with a diagnosis of common (=simple, true or idiopathic) epilepsy.

Veterinarians find no physical or chemical problems in pets that have idiopathic epilepsy when they are not experiencing a seizure. All the blood tests, all the x-rays and all the examinations come back normal. But medical diagnostic equipment is becoming more an more sophisticated as time goes by. So it is probably only a matter of time until we will be able to see what the physical problem actually is in your epileptic pet. (ref1, ref2)

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 more than their fair share of epileptic problems. Seizures also occur more frequently in staffordshire bull terriers ; but those seizures are usually related to a specific neuro-metabolic disorder seen in that breed. (ref)

In cats, the common (idiopathic) form of epilepsy is seen most frequently in Persian and Siamese cats.

Epilepsy is known to effect specific dog and cat blood-lines within a breed more frequently than others. So veterinarians believe that idiopathic epilepsy (the kind that is usually relatively stable from month to month and year to year) is most often a genetically transmitted, inherited disease. (ref). Usually, a parent or a close relative of your pet also had epilepsy. In young adult dogs, the majority of epilepsy is that non-progressive, idiopathic, form. The causes in cats are less clear – probably because it is a less common problem in cats and so, less studied.

It is easy to get confused regarding seizures. All epileptic pets have seizures; but not all pets that have had seizure(s) have epilepsy.

In cats that experience seizures, only about a third to a quarter of the cases are the non-progressive, idiopathic form. In cats, brain inflammations (encephalitis), as yet unexplained degenerative changes in the cat’s hippocampal portion of the brain (ref1, ref2) , exposure to toxic substances, flea and tick control products, traumatic brain injuries, abnormal body metabolism, brain tumors and FIP account for most of the rest. (see more on causes of seizures in cats farther down in this article) Your cat is more likely to be among the fortunate quarter or third if it is less than 3.5 years of age when the problem first begins, is negative for Feline AIDS, Feline leukemia , and the mutated FIP coronavirus and behaves perfectly normal between seizures.

What Is Happening When My Pet Has A Seizure?

It is very frightening to watch a pet experience a seizure. But try to keep in mind that during that frightening experience your pet is not in pain. Your pet may vocalize, thrash around, or void its bladder and intestines, but it does not experience painful sensations. It is just before and just after a seizure that your pet will be frightened, confused and need your reassurance most.

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. Although during a complete epileptic seizure the pet looses consciousness and has no memory of the event ever occurring, there are instances in some dogs and cats where the seizure is partial and the pet is at least somewhat aware of you and things that are occurring around it. Their judgment and behavior in those situations is flawed so they require your caution.

Physicians and veterinarians attempt to subdivide seizure types by the signs that occur and the areas of the brain that they believe are involved. However, there is considerable overlap, the terms are imprecise and a lot of disagreement exits. But here is what I was taught in school: Seizures that put the whole body into severe muscle contractions, are called grand mal seizures. Seizures that are less severe, only affect a few muscle groups or are no more than a brief fainting experience are sometimes called petit mal  or absence seizures. Status epilepticus and cluster seizures are terms used for severe seizures that occur again and again with little or no rest between convulsions. Status epilepticus is exhaustive and can be fatal.

During a seizure, tiny areas of your pet’s brain begin sending out electrical impulses that are received by the nerve cells that adjoin them. This results in a chain reaction (a “storm”) 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.

Secondary Epilepsy and Seizures:

When a defect within the brain can be identified as the source of the abnormal impulses, many vets 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 a brain tumor is present. The same drugs used for idiopathic epilepsy may control those type of seizures for a while ; but unless the underlying cause is determined and successfully treated, the pet’ long term outlook is grave.

Things outside the brain can cause convulsions too. Things like overheating (hyperthermia), low blood glucose (hypoglycemia ), intestinal inflammation or liver or kidney failure (that’s the reason your vet has to run all those expensive tests). Poisons and toxic chemicals can also cause seizures. For example, certain flame retardant chemicals, when eaten, have the ability to cause seizures. (ref). On occasion, Thiamine-deficient diets have also been known to caused seizures in cats. (ref) Pets accidentally consuming  xylitol – containing products can also result in seizures because they cause such a sudden drop in blood sugar. (ref)

More On Epilepsy In Cats:

As I mentioned earlier, idiopathic epilepsy is much less common in cats than in dogs and cats are more likely to develop seizures because of some progressive, acquired brain disease. Because many of these underlying causes have no current effective treatments and tend to increase in severity over time, the long-term prognosis (outlook) for these seizuring cats is not nearly as good as it is for dogs. But even in those cats, your veterinarian can often control the seizures – at least for a time.

I have seen more idiopathic or common epilepsy in pure-bred than in randomly-bred house cats.

Common causes of epileptiform (epileptic-like) seizures in cats (some mentioned previously) include infection with the mutated corona virus of feline infectious peritonitis (“the dry form” of FIP). A rarer cause is infection with toxoplasmosis. Other underlying causes are increased pressure within the pet’s brain (hydrocephalus), liver or kidney disease, low blood sugar, brain tumors, vitamin B-1 deficiency, feline immunodeficiency virus (feline AIDS), rabies, insecticides , antifreeze and migrating parasites (like baylisascaris ). Some of these problems affect the pet’s brain directly; others just weaken the pet’s body defenses in general.

When In Life Does Epilepsy Usually Start And What Does A Real Seizure Look Like?

Most pets have their first epilepsy seizures between 1 and 5 five years of age. During a complete seizure, the pet typically 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 by the seizure the pet can remain consciousness – but its reasoning abilities and mentation are generally flawed until a few minutes after seizure has passed.

Some forms of focal seizures or partial epilepsy are 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 those episodes. Now and then, dog owners tell me that their pet had a “bad dream” – perhaps that was all it was – perhaps there was more to it than that.

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

An epileptic seizure event can be broken down into three distinct stages. It is an ancient disease – written about since writing was invented – so the event has been divided in many ways using many confusing terms with considerable disagreements and overlap. (human nature being what it is, various commissions, study groups and poobahs feel compelled to change the terms and classifications at regular intervals – at just about the time that physicians, veterinarians and the public become comfortable with the terms that are currently in use.)

The first stage is often 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 in their owner is eminent.

The next stage of an epileptic seizure was once called the ictus or ictical stage. This is the time of the seizure itself when the body is subject to uncontrolled movement and thrashing due to the electrical “storm” in its brain. During this stage in a complete seizure, 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.

The final stage of an epileptic seizure is called the postictal  stage. This is the stage of gradual recovery. Dogs and cats in the postictal stage usually appear dazed or hung over. They may bump into objects. These pets are exhausted and sleep a lot. They may have a blank expression or appear to stare out into space.

What Tests Will My Veterinarian Run To Confirm That My Pet Has Epilepsy?

After a thorough physical examination , your veterinarian will likely want to begin with a complete blood chemistry panel as well as a urinalysis of the pet’s urine. If your pet is young or in mid-life and 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 wait to see if the seizures return or begin the pet on an anti-epileptic medication. When the diagnosis is not that certain, the vet can go on to order more specialized tests, such as an MRI , CT scan  or even a cerebrospinal tap (vets often obtain that fluid higher up at the base of the pet’s skull rather than low in the back) until a diagnosis can be made.

What Should I Do During The Seizure?

When a first seizure occurs, owners tend to rush their pets to an emergency veterinary center. There is not much that can be done there for idiopathic epilepsy; but it is a wise thing to do considering all the serious conditions that can mimic epilepsy and that prolonged seizures need to be broken with Valium®. 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. I have never seen or heard of a dog that swallowed its tongue during a seizure. During a prolonged seizure, a dog’s tongue and mouth can turn purple (cyanosis ). But that is because it is having difficulty breathing, not because its airway passage is obstructed by its tongue. Certain breeds with short faces (like bulldogs) spend their lives with borderline respiratory passage obstruction. Those pets, in seizure, are probably at considerably more risk than others.

Seizures that last longer than 5 minutes can become medical emergencies since those pets are having trouble breathing. Have your veterinarian provide you with an emergency vial of diazepam (Valium®) if you pet has experienced such seizures in the past. The bottle says to give diazepam by injection; but it is best placed up the pet’s rectum where it is quickly absorbed. Your vet or their tech will show you how. Give nothing by mouth.

My first concern for pet owners is that they NOT TO BE BITTEN. Do not ever put your hands in or near the pet’s mouth. If your pet or a neighbor’s pet develops a seizure, begin by cautiously manipulating the pet’s head onto a soft folded towel. You may carry the pet in a blanket to a secluded tiled area. Remove all objects that surround the pet so it does not injure itself. Protect it from overheating and stay beside it until the seizure ends.

You can gently stroke and speak calmly and softly to your pet; but the pet will probably 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.

How Soon Should I Start To Think About Continuous Medications For My Pet?

This is a difficult question to answer. After an initial work up, I generally suggest that dogs and cats receive anti-seizure medications if they have had two or more seizures within an 12-14 week period or two or more cluster seizures (acute repetitive seizures) within a 4 week period. Dogs and cats that show unusually severe ictal or postictal periods should also begin medication – with dose and need periodically reevaluated thereafter. When seizures are rare, how frequently – if ever – that an owner can tolerate the sight of a seizure can also be a decision factor.

What Medications Are Available To Treat Epilepsy In My Pet?

Human physicians can be a bit more confident than veterinarians when they formulate a complex epilepsy treatment plan. Veterinarians have a long experience in using phenobarbital and potassium bromide in pets; but only a few limited veterinary studies have been published regarding the long term use of the newer human products in dogs and cats. (ref) And please do remember that idiopathic epilepsy is only an umbrella term for an enormous number of possible epilepsy triggers within your pet’s brain. As in humans, some epileptic pets are resistant to all medications that your veterinarian might prescribe. (ref)

Phenobarbital (aka Phenobarbitone)

Phenobarbital is the most commonly used drug to treat epilepsy in dogs and cats. (The second most common treatment used by veterinarians is phenobarbital combined with potassium bromide.) Your pet’s ideal phenobarbital dose is best determined through measurement of its blood serum phenobarbital levels after it has been on a trial dose for some time and periodically there after. (ref) Phenobarbital can have negative effects on your pet’s liver. That is why the previous (ref) suggests liver function tests (including bile acids ) as well.

The side effects of phenobarbital can be sedation, increased appetite, weight gain, increased thirst and urination. It is impossible to predict which pets will show any of those side effects and to what degree. Many side effects decrease after their body has adjusted to the medications. These problems, when they are significant, can often be minimized when the dose is closely regulated or if a combination of medications is used that lower the phenobarbital dose. My article on NeuroCare™ and MCTs suggests other possible ways. 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.

Some veterinarians suggest give epileptic pets milk thistle as a liver protectant. (A 2012 scientific study of milk thistle’s “active” ingredient, silymarin, found it of little or no value in humans with one form of chronic hepatitis ref. A 2007 study had reached a similar conclusion on its use in various human liver problems. (ref) Silymarin is one of the two “active” ingredients in Denamarin™. A 2016 study on silymarin’s use as a liver protectant in overweight mice was considerably more up beat.) (ref)

Potassium Bromide

Combining phenobarbital with a second drug, such as potassium bromide, may lessen the chances of liver damage in your pet by allowing a lower phenobarbital dose. Dogs taking potassium bromide should receive it with food. Owners need to be careful with the salt levels in their pet’s diet and whenever the brand of dog food they offer is changed [higher salt diets and salty treats can decrease the level of KBr in their body (ref)]. 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 associated with a type of lung inflammation called pneumonitis. (ref) When pneumonitis occurs, it can produce signs quite similar to feline  asthma .

Primadone (Mysoline®, Mylepsin®, etc.)

The effects and side effects of primadone are similar to those of phenobarbital. That is because the majority of primadone is converted to phenobarbital in your pet’s body. In the majority of studies I know of, primadone was no better than phenobarbital in controlling seizures. In most studies, primadone was a bit less effective than phenobarbital, and in none of the studies I know of was it any better than phenobarbital.

Imepitoin (Pexion®)

You can read an article just on Pexion through the link above. As of mid 2017, Pexion is available in Europe, the UK and Australia, but not in North America. No one has offered me an explanation for that, but I am guessing it is due to bureaucratic hurdles.

Valium® (diazepam)

This drug, given alone, is only effective in ending dangerous long-lasting seizures until another medicine can take over long term seizure control in your pet. In dogs and cats, it is quite good at breaking those 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.

Newer Medications

Levetiracetam ( Keppra®)

This medication is sometimes used in dogs in combination with phenobarbital and potassium bromide to lower the daily dose of phenobarbital received and in cases where phenobarbital and potassium bromide were not able to control the seizures sufficiently. This is the most recent study of its use in dogs that I know of: (ref) The drug appears quite safe. Rare side effects in dogs include stiff wobbly gait, vomiting and salivation. It requires frequent dosing

Neurologists occasionally find that levetiracetam, given alone (“monotherapy”) , is sufficient to prevent epilepsy in people. That’s an “off label” use because the FDA only approved it as an add-on medication [but for reasons as much bureaucratic as scientific (ref)]. For those same sort of reasons, veterinarians can be reluctant to experiment with new epilepsy monotherapies as well. So if your pet stayed seizure-free (or didn’t) while taking only levetiracetam (Keppra®) let me know and I’ll pass that information on to other readers. You can read their responses here.      

Zonisamide (Zonegran ®)

Zonisamide is sometimes effective in blocking seizures in dogs and cats. It has few common serious side effects that we know of (when they do occur it is generally vomiting, lack of appetite, sedation, lethargy or a wobbly gait) (ref) ; but, occasionally, side effects can be more severe (ref1, ref2, ref3, ref4) But most dogs have no apparent problems with the drug. More cats than dogs have side effects. It is available in generic form. Zonisamide can cause a pet’s thyroid hormone (T4) levels to decrease. So it might be wise to document the pet’s T4 level before beginning the drug. When it is used, it is usually as an add-on therapy for dogs already receiving phenobarbital. When added, the phenobarbital dosage can sometimes be drastically reduced (in a few cases, entirely eliminated). Unlike levetiracetam, it can be effective given twice, rather than three times a day. (ref)

An earlier version of this article discussed the possible use of felbamate ( Felbatol®), clorazepate ( Tranxene®), gabapentin (Neurontin®) and, valproic acid ( Depakote®) as possible aids in the control of idiopathic epilepsy in pets. But the 2015 ACVIM (American College Of Veterinary Internal Medicine) epilepsy treatment guidelines no longer suggest them. (rptref) Their international counterpart no longer suggests them either – but they do still discuss those medications and a few others. (ref)

Can I Ever Stop Giving My Pet Medications?

Pets that were put on long term phenobarbital because they had one or two seizures, little laboratory and physical work ups and no family history of the problem probably shouldn’t be on it at all.

Adding supportive medications that keep you pet as functional and healthy as possible after a period on its initial medications and attempting to find the lowest effective doses that keep the pet seizure-free or seizures to a minimum is always desirable. All changes need to be gradual and done in consultation with your veterinarian. Try to make those changes when your household is not under stress and when you know that your favorite veterinarian will be available.

In my experience, few truly epileptic dogs or cats stay seizure-free without any medication. But it probably occasionally happens. It does in humans. (ref)

Might My Pet’s Diet Affect The Number and Intensity of Its Seizures?


There is some evidence that in humans at least, diets high in fat and low in carbohydrate might be beneficial in controlling epilepsy. You can read a review of that information 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.) Be sure to read the link to the NeuroCare™ diet as well. You might also try to slowly changing the amounts you feed at each meal and the frequency between them. Smaller, more frequent feeding are known to change many aspects of metabolism – sometimes for the better. [ I cannot bear to see my Labrador, Max, hungry; and I believe that given the chance, he would eat till he exploded. But periodic fasting was the only thing that Hippocrates knew of that would lessen the “falling sickness” (ref). I am not suggesting that for your pet, but I thought you ought to know ]

Will Idiopathic Epilepsy Shorten My Dog Or Cat’s Life?


Typically, idiopathic epilepsy will not shorten a dog’s life. That is probably true for cats as well. It is dogs and cats that have progressive brain disease that trigger seizures that are ever more severe and those with other concurrent health issues that will eventually pass away from the problem. (ref1, ref2, ref3)

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