Epilepsy

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Epilepsy

Introduction

Epilepsy is a condition that can affect any breed of dog.
It’s 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.There is a higher incidence in pure
breed dogs of any size than in mixed breed dogs, and is
therefore likely to be inherited.




Poodle

What is
epilepsy


Epilepsy is a functional abnormality in a neuron that
causes an abnormal neurologic excitation that generalizes
to the whole brain. It is similar to a lightning strike on
a house that sends abnormal current through the normal
electrical system.

Types of
Epilepsy


Primary epilepsy: also
known as idiopathic, genetic, inherited, or true epilepsy.
There are no positive diagnostic findings that will
substantiate the diagnosis. It is a case of ruling out
every other possibility. The first seizure in a dog with
primary epilepsy usually occurs between the ages of 6
months and 5 years. (Oliver, Seizures). However, a
diagnosis of primary epilepsy is not proof of a genetic
defect; only careful breeding studies could prove that. The
breed, the age, and the history may suggest a genetic basis
for primary epilepsy if there is a familial history of
seizures.

Secondary epilepsy
refers to seizures for which a cause can be determined, and
there are many. In dogs less than one year of age, the most
commonly-found causes of seizures can be broken down into
the following classes: degenerative (storage diseases);
developmental (hydrocephalus); toxic (lead, arsenic,
organophosphates, chlorinated hydrocarbons, strychnine,
tetanus); infectious (distemper, encephalitis, and others);
metabolic (such as transient hypoglycemia, enzyme
deficiency, liver or kidney failure); nutritional
(thiamine, parasitism); and traumatic (acute injury).

In dogs 1-3 years of age, a genetic factor is most highly
suspected. In dogs 4 years of age and older, seizures are
commonly found in the metabolic (hypoglycemia,
cardiovascular arrhythmia, hypocalcemia, cirrhosis) and
neoplastic (brain tumor) classes. Seizures are also
associated with hypothyroidism, which is a familial
(inherited) autoimmune disease of purebred dogs.

Signs
The main sign of epilepsy is seizures, which can
be categorized in three ways. Intracranial causes of
seizures have detectable defects, such as a tumor, inside
the brain. Extracranial causes of seizures have metabolic
or toxic changes that are outside the brain but affect the

brain to cause a seizure. Seizures of unknown cause form
the third category, called idiopathic epilepsy.

Seizures in a dog less than one year of age are likely to
be caused by congenital/genetic problems, infections, or
toxins. A dog greater than six years old is likely to have
tumors or infectious/inflammatory problems that are causing
the seizures. Dogs between 1 and 5 years of age that are
normal between seizure episodes are most likely to have
idiopathic epilepsy. 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. 

Recognizing a seizure is important and often difficult. A
seizure can be minor and show as only slight loss of muscle
control (called a partial motor seizure), or it can be
severe, with the dog paddling on the ground completely out
of control (called a grand mal seizure). In general, a dog
will lose bladder and bowel control during a seizure, will
be unaware of its surroundings, and will appear abnormal
after a seizure.

Types of
seizures


• 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.

Treatment

Treatment for epilepsy does not cure dogs of the disease.
Instead, the goal is to control the seizures. Left
untreated, this disease and its signs will continue to

worsen.

The first line of treatment for epilepsy is a barbiturate,
usually phenobarbital. This drug has anti-seizuring effects
and can be used to treat dogs over the long term. The
general goal of therapy is either to reduce the number of
seizures by half or to double the time between seizures.
This goal does depend somewhat on the individual case. In
some cases Valium may be used when Phenobarbital cannot be
utilized or when a combination of medications are
prescribed. 

Diazepam (Valium) is also used for treatment of status
epilepticus.

The second-line drug that is used in the treatment of
epilepsy is potassium bromide. This drug does not have FDA
approval and is available to treat seizures in dogs by
special license only.

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.

Why
Treatment Fails


There are many reasons why medical treatments can fail.

The biggest reason is the owner’s lack of proper
administration of the prescribed drug. The progression of
an underlying disease (such as brain tumor) may resist
treatment. Also, gastrointestinal disorders can affect drug
absorption, and tranquilizers may stimulate seizures. Drug
interactions can occur and adversely affect the level of
anticonvulsant drug in the dog’s system. And it just might
be that a particular drug may not work for that animal.

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. 

It is important to
note that an epileptic dog can live a normal life with
proper treatment but usually will not live quite as long as
a normal dog. If you would like further information,
contact your veterinarian.



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