A seizure is defined as a paroxysmal, transitory disturbance of brain function that has a sudden onset, ceases spontaneously, and has a tendency to recur. Generalized seizures affect the entire body. Most commonly, animals will fall to the side, make paddling movements with the limbs; they will often will urinate, salivate and defecate during the episodes. Generalized seizures usually last from several seconds to upwards of a couple minutes. Focal seizures remain localized to one body region and are usually shorter in duration, lasting a couple seconds. Seizures may start focal and then become generalized.
After the veterinarian is convinced that a seizure disorder is present, the most important question to be answered is whether the seizure is the result of primary brain disease (intracranial disease), or the result of a disturbance outside the brain (extracranial disease), The most common intracranial causes of seizures include: structural disease including hydrocephalus, head trauma, inflammatory brain disease (encephalitis), strokes and neoplasia (brain cancer). The most common causes of extracranial diseases that cause secondary brain signs include: toxins and metabolic diseases. Metabolic diseases include: low blood sugar (hypoglycemia), high blood sugar (hyperglycemia), liver disease, kidney disease, electrolyte disturbances, toxins (poisons), anemia.