Idiopathic epilepsy is a term used for a group of seizure disorders that occur due to abnormal electrical activity in the brain where no structural brain abnormalities exist.  Epilepsy is a rule-out disease.  Trauma, toxins, viral diseases and brain tumors can also cause seizure-like activity.  New anti-epileptic drugs allow many dogs with epilepsy to live normal lives.  Idiopathic epilepsy has many presentations and is not always a grand mal seizure where the dog loses consciousness and thrashes around.