What is Canine Epilepsy?
Epilepsy is a chronic condition characterized by recurrent seizures. Although seizures are always abnormal events, not
all seizures in dogs are caused by canine epilepsy.
Epilepsy is a disorder of the brain where abnormal electrical activity triggers further
uncoordinated nerve transmission. This
uncoordinated and haphazard nerve tissue activity scrambles messages to the muscles of
your dog's body and the coordinated use of the muscles is then inhibited.
are many causes of chronic recurrent seizures in dogs, canine epilepsy is not a specific
disease or even a single syndrome, but rather a diverse category of disorders. Canine Epilepsy is broadly divided into idiopathic
and symptomatic disorders. Idiopathic
Epilepsy, also called primary epilepsy, means that there is no identifiable brain
abnormality other than seizures. Symptomatic
epilepsy (also called secondary epilepsy) is seizures that are the consequence of an
identifiable lesion or other specific cause.
Most dogs with idiopathic epilepsy suffer their first seizure between the ages of one and five years of age. A genetic basis for idiopathic epilepsy is strongly suspected in several breeds including the Beagle, Belgian Tervuren, Keeshond, Dachshund, British Alsatian, Labrador Retriever, Golden Retriever and Collie. Idiopathic canine epilepsy may have an inherited basis in other breeds also.
a beloved dog in the throes of a grand mal seizure is one of the most terrifying scenes
you can witness. A seizure refers to the
involuntary contraction of muscles. The
seizure is caused by an electrical storm in the brain.
Seizures can be broken into two types, generalized and partial. In a generalized seizure, the electrical storm
appears everywhere at once. In a partial
seizure, the abnormal electrical impulses begin in a small area of the brain.
tonic-clonic (formerly called grand mal) seizure: The
seizure begins with contraction of all skeletal muscles and loss of consciousness. The dog
usually falls to his side with the legs stretched out and the head back. This is the tonic portion of the seizure. Sometimes he will vocalize or have facial
twitching. Vocalizations are involuntary and
do not indicate pain. Often the dog will
drool excessively, urinate, defecate or eliminate his anal glands. The tonic portion of the seizure is usually very
brief and gives way to the clonic phase of the seizure.
Once the clonic phase begins the dog will have rhythmic movements. Typically this consists of clamping the jaws and
jerking or running movements of the legs.
seizure, the dog may lay motionless for a brief period.
Eventually he will get up on his feet and may appear to be perfectly normal, but
typically will show signs of post ictal behavior. These
signs may include blindness, disorientation, pacing or running about the house bumping
into things. The post-ictal behavior can last
anywhere from hours to days after a seizure.
Not all generalized seizures follow this pattern. Another type of generalized seizure is the tonic seizure, in which motor activity consists only of generalized muscle rigidity without the clonic phase. Less common are clonic seizures where there is no tonic phase and some dogs suffer milder generalized tonic-clonic seizures in which consciousness is maintained.
seizures: Partial seizures are
also called focal seizures and as the name indicates, the electrical storm is affecting
only a part of the brain. A partial seizure
may stay localized or it may expand to the whole brain and cause a tonic-clonic seizure. Because the seizure starts in only a part of the
brain, an underlying disease or injury is highly suspected.
A partial seizure may remain localized or spread to other parts of the cerebral
cortex producing a sequential involvement of other body parts.
seizures are classified as simple focal seizures when consciousness is preserved and as
complex focal seizures when consciousness is altered.
Any portion of the body may be involved during a focal seizure depending on the
region of the brain affected.
In a simple
partial seizure, the area of the brain that is affected is the area that controls
movement. Usually the face is affected,
resulting in twitching or blinking. This is
usually limited to one side of the face. If
the seizure spreads, other parts of the body on that same side will be affected. The dog is usually alert and aware of his
A complex partial seizure will originate in the area of the brain that controls behavior and is sometimes called a psychomotor seizure. During this type of seizure, a dogs consciousness is altered and he may exhibit bizarre behavior such as unprovoked aggression or extreme irrational fear. He may run uncontrollably, engage in senseless, repetitive behavior or have fly-snapping episodes where he appears to be biting at imaginary flies around his head.
Cash WC, Blauch BS: Jaw snapping
syndrome in eight dogs. JAVMS 175:179, 1979