Epilepsy in Dogs
What we need to Know to Understand it
One of the most terrifying scenes a pet owner can witness is that of a
pet in the throws of a grand mal seizure. Once seen, it will never
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 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.
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
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.
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.
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.
The 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.
The 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 that 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.
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
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.
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.
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
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.
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
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!