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EPILEPSY IN THE DOG
by T. J. Dunn, Jr. DVM

Epilepsy in dogs, petit mal seizures, and grande mal seizures, are some of the most terrifying scenes a pet owner can witness. Once seen, it will never be forgotten.  Epileptic episodes are quite common in dogs and actually show up more often in certain breeds of dogs than in others.  For unknown reasons, epilepsy in cats is rather rare.  When seen in a cat, epileptic episodes may have more serious underlying mechanisms than when present in dogs. Let’s explore this disorder a bit and we will gain a better understanding of just what is going on during an epileptic episode.

First we need to know the terms…

EPILEPSY is defined as a neurological disorder characterized by sudden, recurring attacks of muscular, sensory, or psychic malfunction with or without loss of consciousness or convulsive seizures.

A SEIZURE refers to the involuntary contraction of muscles.  Seizures can result from abnormal electrical activity in the brain brought on by tumors, blood clots or scar tissue, or from chemical imbalances such as low blood sugar or nerve stimulating drugs.  Tetanus toxin poisoning can stimulate muscles to contract resulting in a seizure.   A seizure may involve all the skeletal muscles or be localized to spasms in a single bundle of muscles.  When we see an athlete fall down, stretch and massage the calf muscle during a muscle cramp… those calf muscles are in a state of seizure due to lactic acid buildup from changes in oxygen availability within the muscle.

A GRAND MAL SEIZURE refers to severe, widespread cramping of the body’s skeletal muscles.  Skeletal muscles in general are those that attach to bones and allow for body movement; there are special smooth muscles that don’t attach to bone that usually are unaffected during a seizure.  These smooth muscles reside mainly in the intestinal tract, blood vessels and specialized organ tissues. The heart muscle is actually different from either skeletal muscle or smooth muscle. Grand mal seizures are rather shocking to see.

A PETIT MAL SEIZURE, see the short movie below, is a less severe form of seizure where the patient still has some voluntary control of movement and coordination but where certain muscle groups are “doing their own thing” and brain electrical activity is mildly disrupted. Staggering, momentary “staring into space” and other forms of incoordination may be visible to an observer.

CONVULSION usually refers to a grand mal seizure.  Sometimes these terms are loosely applied to an epileptic episode.  We might say a patient is having an “epileptic attack”, or “is having a seizure” or maybe even a “fit”.  However we describe it, the occasion will be uncomfortable for the observer and the victim.

STATUS EPILEPTICUS refers to a very dangerous situation where a rapid successions of grand mal seizures occur without periods of rest or muscle relaxation between epileptic episodes.  Status epilepticus requires prompt medical intervention.

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GENERAL DESCRIPTION
True epileptic episodes where the triggering mechanism is not due to poison, low blood sugar or other chemical stimulants have their origins within the brain tissue.  Researchers believe that there is a locus (an actual spot or area in the brain) of abnormal or damaged brain nerve tissue.   This tiny area may be of no consequence 99.9 percent of the time.  But for various reasons such as dietary, chemical, or even psychological, this tiny locus of abnormal nerve tissue decides to start firing off signals.  The nearby normal nerve cells are affected by these wayward nerve impulses and respond to them.   This response then triggers other nearby nerve cells to fire and the outcome of this electrical chain reaction is a total loss of coordination!  

The nerves from the brain that stimulate the voluntary muscles of the body (called motor nerves) are telling the muscles to get to work, but without proper supervision and control the different muscle groups are contracting without integrated coordination.  Think of this as an orchestra where all the musicians are playing the same song except that the conductor isn’t present.  Each musician starts and stops the melody at their own discretion without regard to what any other musician is doing.  Surely not a pleasant thought… harmony, coordination and melody no longer integrate the music. And so it is with EPILEPSY.  The harmonious and finely tuned integration of nerve transmission directing coordinated muscle movement is lost.  The result is a seizure. 

If this occurs in your pet, your first reaction is to race to the phone and call your veterinarian for help.   Fortunately almost all epileptic episodes are of short duration… one to three minutes is most common.  Five to ten minute episodes are getting into the more serious range of duration; and any seizure lasting longer than fifteen minutes generally requires medical attention.

A typical Grand Mal seizure may look like this:  The dog will seem perfectly normal when, without warning, it begins to stagger just a bit when walking.  Then it may appear to be backing up, will sit down on the hind legs and the facial muscles and eyelids will begin to spasm.  (This is termed “muscle fasciculation”).  Often the jaw muscles will spasm and the dog will appear to be “chattering his teeth” and will begin to salivate.  Breathing will become forced and if the jaw is set in a closed position the forced breathing will stimulate the saliva to foam up.  Now the dog appears to be “foaming at the mouth.” 

On other occasions the jaw will be held involuntarily in an open position and appears as if the dog is trying to yawn… or even as if to scream out and no voice is heard.  This truly can be an unpleasant and scary experience for the dog and the owner!  As the event continues the dog may fall over on its side, and stretch out with legs and neck extended, eyes rolled back, mouth foaming and the entire body going into a rigid state.  Now it appears that the dog cannot breathe because of the intense muscle contractions and stiff posture.  

After a few seconds (surely seems like minutes!) the dog begins to relax, the breathing returns to normal and voluntary movement becomes more evident.  Here’s an interesting phenomenon:  If the breathing is so interrupted that the dog begins to lose consciousness, the oxygen deprivation to the brain shuts off the seizure!  So just when you think your dog is dying the seizure stops!  Anyone watching the event returns to more normal breathing, too!  After a few moments the dog will sit up, begin to “shake it off” and go back to normal activities as if to say “What was the deal with THAT?”

From start to finish the entire event may last from one to five minutes… just enough time to get the veterinarian on the phone to tell the veterinarian you think your dog is dying.  Commonly, the dog will act placid and quiet for an hour or so after a seizure.  By the time you describe over the phone what has transpired, the dog is often up and aware and looking for that rawhide chew toy it was working on just before he was interrupted. The veterinarian will ask you to describe what you saw and will then give you advice about what to do next.  

And that is to have the dog examined… maybe not necessarily immediately as long as you can stay in touch with the veterinarian in the event that other seizures follow.  But surely any dog that has experienced a seizure should be examined and some blood tests should be run to gain some knowledge of the dog’s physical and biochemical status.

THE EXAMINATION
During the complete physical exam the veterinarian will want to pay close attention to the heart and to neurological signs.  Often the physical exam is normal… you have a physically healthy dog who happens to scare the biscuits out of you with unannounced seizures!   During the office call your veterinarian will obtain a blood sample for laboratory tests to get an insight into the dog’s invisible metabolic goings-on. 

BLOOD SAMPLE
Blood samples are a vital tool in determining whether or not chemical imbalances are at the root of the epileptic episodes.  For example, the liver has thousands different tasks to perform and if any are not accomplished properly the effects may impact the nervous system and a seizure may result.  Blood sugar concentrations have to be regulated within certain boundaries otherwise neurological and other difficulties will arise.  And electrolytes, such as sodium, potassium, calcium and phosphorus all need to be present in the blood in an interrelated and coordinated fashion for healthy neurological and biochemical reactions to occur. If the veterinarian discovers an imbalance in any of the blood chemistry values, detective work follows that may result in a diagnosis of what is causing the seizures. 

URINE SAMPLE
A urine sample can reveal infections of the urinary tract although urinary infections rarely will affect the neurological system.  Relative to seizure activity, the urinalysis may reveal sugar in the urine that suggests a diabetic condition might exist.  Ketones in the urine may be revealed which suggests the excessive utilization of protein, instead of carbohydrates or fat, for energy.   Acid, protein and bile constituents may be seen in higher amounts than normal.   Any abnormal urine factors are hints that something in the body’s chemistry in not right and further tests are needed.

But guess what?  Over ninety percent of dogs that exhibit epileptic manifestations will have NORMAL blood and urine values!  In fact, that is what veterinarians hope for when checking laboratory values in suspected epilepsy patients.  They want to see that everything is functioning properly. 

So now you are asking, “If all those tests are normal, what is causing the epileptic episodes?”   Veterinarians have a diagnosis for these cases… they will remark with profound confidence that your dog has IDIOPATHIC EPILEPSY.  “Oh,” the owner responds.  “What does that mean?”  And the veterinarian replies, “That means we don’t know what the cause is.”  IDIOPATHIC EPILEPSY means the actual cause of the seizure activity is unknown. Researchers believe that if we could look all through the brain with a tiny microscope we would eventually find a small bundle of nerve cells that aren't quite normal.  It would be this locus of nerve cells that for various reasons begin to fire off impulses on their own.  Those renegade nerve firings trigger other neighboring nerve cells to respond.  This starts a cascade of nerve firings that spreads out from those renegade cells and pretty soon the whole electrical harmony of the brain is upset.  A seizure is the result. 

WHAT CAUSES EPILEPSY IN THE FIRST PLACE?
What creates those little renegade bundles of nerves?  One of the theories is that a head injury resulted in a small hemorrhage into the brain.  As the blood clot resolves and reabsorbs, scar tissue can remain behind that interrupts normal nerve cell integrity.   Small tumors can be a source of abnormal nerve activity.  That’s why any case of epilepsy that seems to be progressively worsening should have brain tumor considered as a possible inciting cause, especially in epileptic cases that have an onset in middle or old age.

Genetic predisposition for epileptic activity has been shown in certain breeds of dogs.  The exact mechanism whereby the genetic determiners impart their influence on nerve cells is yet to be discovered.

Psychological stimuli can play a role, too.  I know of a case where the pet owner’s little dog got so stressed every time the owner was preparing for a trip (without the dog) that the little rascal would work up to an actual seizure episode!  Talk about trying anything to get your own way…

An unusual food allergy may be at the heart of the matter, too.  To establish a food-related trigger for epilepsy will take a skilled and persistent diagnostician, in cooperation with very complying owners.

PREVENTION
What can be done to prevent epileptic episodes?  The answer depends upon a number of variables.  If the dog has had only a single episode and physical exam and lab tests are normal and the diagnosis is IDIOPATHIC EPILEPSY (we really do not know the cause), probably no medication is required.  However if the dog begins to show some sort of pattern to the episodes, let’s say that the seizures are happening about every three or four weeks, you may wish to consider starting low doses of medication to try to inhibit the seizures.

It is very important to develop a close relationship with your veterinarian on this matter of whether or not to prescribe medication.  If the dog is having a two minute seizure every six months, does that suggest the dog should be given medication every day to keep these infrequent episodes from happening?   Be sure to keep good notes:  Record the date, time of day, related environmental factors, length of time the epileptic episode was evident and severity of the seizure.

If the seizures are of the petit mal variety and last just a few seconds, even if they occur fairly frequently, should the dog be medicated daily as a preventative? You see, we can’t predict when these episodes will occur so giving preventative medication is an ALL OR NOTHING commitment.  If we knew that every Saturday at five o’clock the dog would have a seizure, we could start medication twelve hours prior to that, prevent the seizure, then cease giving the medication until next week.  Unfortunately that scenario doesn’t happen.  The situation calls for an either/or commitment.  Medication is given daily for a period of time or no medication is given at all.  Some patients, after many months or years of treatment, can be weaned slowly off medication and experience no further epileptic episodes.

TREATMENT
Fortunately most cases of epilepsy can be controlled.  Cured?  Probably not, unless an underlying triggering mechanism is discovered and rectified.  Also, if the seizure activity is due to a tumor it is unlikely that attempts at controlling the seizures will be successful.  Many cases of epilepsy in dogs will dictate that treatment be instituted. Follow-up blood analysis is recommended at selected intervals to be sure the correct levels of medication are being given and that no abnormal blood values are starting to show up.  Fortunately, many dogs that have been treated for epilepsy over a period of time can slowly be taken off medication, and eventually not require any further medication.  (Never abruptly eliminate anti-epileptic medication!  Sudden withdrawal of medication often will trigger a long and difficult seizure episode.)

Phenobarbital is the most commonly used medication to treat epilepsy in the dog.  If given in the lowest dose required to keep the seizures to a minimum, Phenobarbital can be a very useful medication with minimal side effects.  Many dogs being given Phenobarbital are living very normal and happy lives.  Some pet owners are adverse to giving their dog a “drug” for long periods and look at the situation of having a pet that is “drugged-up all the time” to be unacceptable.  Most veterinarians agree, too, that if the dog requires such high levels of medication that it acts and feels “drugged-up” that this scenario is unacceptable. Fortunately, the majority of cases will be helped by medication with little, if any, side effects.  The “side effect” we are looking for is the elimination for those awful seizures!

A drug called Dilantin (phenytoin) has been used for years but in general has been a secondary choice after Phenobarbital. 

In some cases Valium may be used when Phenobarbital cannot be utilized or when a combination of medications are prescribed. 

Potassium bromide (KBr) is being used in some dogs where response to traditional medication is unsatisfactory. Potassium Bromide had been used to treat human epileptics for over 100 years. It may be the anticonvulsant of choice for dogs with liver disease.   Sometimes veterinarians will prescribe KBr along with Phenobarbital for patients who do not respond well to Phenobarbital alone. KBr is not easily obtained and may require a pharmacist to acquire and formulate the proper dose.

Just as the brain must be in good balance with the rest of the body, so should we look for a balance in the treatment of epilepsy.  Too much medication is not good because we don’t want the pet to have dulled senses; reoccurring seizure episodes are unacceptable so we may need to use a little medication.

Any dog receiving anti-epileptic medication should have periodic blood samples evaluated for blood chemistry balance.  Since many medications are degraded and eliminated from the body via the liver, an assessment of liver function is a priority.

WHAT TO DO DURING A SEIZURE
If you happen to witness a seizure, there is not much you can do at home to get it under control.  Try to remove any objects from the immediate area that the dog may bump in to and injure itself.   Do not try to open the dog’s mouth to pull the tongue out.  Although it can happen, it is extremely rare for the dog to “swallow the tongue” and obstruct the airway.  Plus the strength of the dog’s jaws will probably prohibit any attempts you make to open the mouth to inspect the area. 

NOTE: If your dog is actually choking on something and is consciously gagging, hacking, salivating and in trouble breathing, you may need to intervene.  However this discussion concerns how to deal with the epileptic patient displaying seizure activity as described previously.  Visible choking and gagging may require that you inspect the mouth for objects.

It may be helpful to gently talk to the dog and to try to make the dog comfortable during the seizure activity by rolling it onto a blanket or padded mat.  If you try to pick the dog up you will need to be very careful because the dog will be thrashing about and you very likely will lose your grip and drop the dog.  Try to turn off any loud music or other stimuli such as bright lights, and escort any screaming children away from the area.  They can watch but they need to be silent.  “Do something!! Do something!! ” is the high pitched phrase most often heard during one of these episodes. However, about all you can do is wait.

The most troubling thing you may witness occurs just before a Grande Mal seizure is over.  The dog stiffens up, ceases to breathe, and just when you think death has visited the dog, it relaxes and begins to breathe again.  In fact what has happened is that the interrupted breathing and resulting carbon dioxide buildup depresses nerve function and terminates the electrical chaos in the brain... and the seizure is turned off.  Another marvel of survival!  It is as if the dog’s survival center says “Seizure, you want to lock me up in a big muscle spasm and suffocate me?  OK.  I’ll show you.  When I’m unable to breathe the brain will be starved for oxygen and shut down.  When those nerve cells that triggered the seizure become deprived of oxygen they'll shut down, too... and the seizure will stop!"

The fact is that EPILEPSY, although truly a challenging condition in the dog, in most cases can be dealt with successfully.  Cured... no; managed... yes.  Just as each and every pet is a unique individual, every case of epilepsy should be dealt with on an individual basis.  Some dogs will never have a seizure, some will have a single seizure and never another, some will have predictable intervals between chronic seizures, and some will have untreatable, repeating and debilitating epilepsy.  No two cases will be exactly alike!