| CANINE
EPILEPSY
Canine epilepsy is a brain disorder that is characterized
by repeated intermittent seizures usually occurring between
6 months and 5 years of age. Epilepsy is a result of a bioelectrical
disturbance in the brain commonly referred to as an “electrical
storm”. The brain is structurally normal but brain
function is irregular. Epilepsy is genetic in origin but
the mode of inheritance is unknown.
Epilepsy is more frequent in inbred dogs and the Siberian
Husky is one of the top ten breeds affected. The most common
age affected is between 6 months and 3 years of age. Males
are more commonly affected with epilepsy in all breeds.
Historically, most epileptic seizures occur when the dog
is resting or asleep although periods of intense stress
can trigger seizures. The most common time of the day for
seizures are early morning or late at night. Seizures usually
start as a mild episode of twitching, confusion, trembling,
and in-coordination and typically include salivation, defecation,
and/or urination. Periods of confusion may follow the seizure
with pacing and anxiety. The pet usually returns to a normal
mental state shortly after the seizure. Most pets know that
a seizure is about to occur “prodromal stage”
and may become anxious, withdrawn, or clingy hours or days
before the seizure occurs. The owner can usually recognize
this prodromal period. In general, seizures that occur before
2 years of age are more difficult to treat and control than
seizures occurring at an older age.
Epileptic seizures usually are convulsive without loss
of consciousness and include altered mental states. Seizures
are usually gradual and start on a monthly basis or longer.
If the first seizures are multiple, reoccur within short
intervals, or are violent and/or long in duration the diagnosis
of genetic or idiopathic epilepsy is in question. It is
very important to seek immediate medical attention for your
pet if the seizures are clustered, prolonged, or intense.
These types of seizures are life threatening and require
immediate veterinary treatment. If your pet is having a
seizure, remove objects that may harm your dog from the
area. Do not try to open the mouth of the dogs since dogs
rarely swallow their tongues. The best way to protect the
dog from injury is to wrap the body of the dog in a large
blanket until the seizure is finished. Dog bites may occur
since the dog has no idea that the owner is trying to help.
The stages of a seizure can be divided into prodromal,
aura, ictus, and postictal stages. The first stage, prodromal,
precedes the seizure from several hours to several days.
The dog shows changes in behavior, which is observed by
the owner. The second stage, the aura, may or may not occur
in all dogs. The dogs become very restless with whining,
restlessness, hiding, salivation, and/or vomiting which
lasts for several seconds to minutes. The third stage, ictus,
is the actual occurrence of the seizure that includes loss
of muscle tone and may or may not include loss of consciousness.
The dog can stretch the forelegs, fall over, twitch, convulse,
have running movements, and urinate and/or defecate. The
actual seizure can last from several seconds to several
minutes. The last stage, postictal, is the period where
the animal recovers and gets up. The pet may be disoriented
and confused. This phase can last several minutes to several
hours and it is not uncommon for the dog to become extremely
thirsty or hungry.
A normal brain tissue without any disease characterizes
hereditary epilepsy. The dogs are completely normal in between
seizure activity, which usually occurs within a one to four
week period. All the laboratory tests including blood work,
EEG, and MRI are normal. It is assumed that different genes
and genes complexes with variable penetrance are responsible
for epilepsy. In Golden Retrievers and Labrador Retrievers,
a multi-factorial and autosomal recessive group of genes
cause epilepsy.
Treatment is started for epilepsy if the seizures occur
more than once a month or if the seizures are multiple or
intense in nature (status epilepticus). The two most common
drugs for treatment are Phenobarbital and potassium bromide.
Phenobarbital is usually tried first to control the seizures
since the drug is inexpensive and easily available. Blood
levels need to be checked on a routine basis to determine
if the dosage needs to be adjusted and the liver enzymes
evaluated for increased values. If the seizures are not
controlled on Phenobarbital or the liver enzymes are elevated,
potassium bromide can be used. This drug is more expensive
and needs to be compounded by a pharmacist. It is not available
as an approved drug for pets. No matter which drug is used,
pet owners should maintain a calendar of seizure activity
to assess treatment. Once a drug is started, it cannot be
discontinued abruptly and the pet is usually on the drug
for life. The dogs affected should not be bred and neutering/spaying
considered. Females in heat can have seizures of increased
frequency due to stress.
Kathleen Stryeski, DVM
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