Seizures can occur in any species but occur more commonly in dogs. Extracranial (outside the brain) causes of seizures include poisons or toxins. Cardiac or respiratory abnormalities which cause hypoxia (lack of oxygen) can result in seizures. Metabolically induced seizures (i.e. from liver disease, kidney disease, or diabetes mellitus) are generally reversible once diagnosed and treated. Intracranial (within the brain) etiologies represent the most common cause of seizure disorders. Epilepsy is the most frequently diagnosed intracranial cause of seizures. Individuals from almost every breed of dog have been diagnosed with congenital (present at birth) epilepsy, but inherited epilepsy has only been diagnosed in a few breeds. Canine distemper can cause seizures and is seen in both young and old dogs. Feline infectious peritonitis (FIP) and feline leukemia virus (FELV) can also cause seizures.

Bacterial encephalitis can result from an infection in the blood stream or from infections extending from the eyes, ears, or nose. Clinical signs vary from depression, rigidity, and fever to seizures. Tumors (neoplasia) that occur in the brain can be benign or malignant and frequently elicit seizure activity. Acquired or inherited hydrocephalus (abnormal accumulation of fluid in the brain causing enlargement of the skull and pressure on the brain) can also cause seizures. Intracranial trauma with anoxia (loss of oxygen) or subsequent scar tissue formation can result in seizure disorders. These seizures may not arise for weeks or even years after the initiating event occurs, making the diagnostic workup far more important than the recent history.

Epilepsy originates from a cluster of physically normal, but electrically malfunctioning, nerve cells. The abnormal electrical discharges cause no problem as long as they do not reach a specific level. However, at the threshold level the electrical discharges recruit adjacent neurons (nerve cells), the activity spreads, and either mild (petit mal) or severe (grand mal) seizures develop. Treatment is aimed at making the seizure threshold harder to reach or at limiting the spread of the abnormal electrical activity. In certain toy breeds (Poodle and Pekingese) the seizures are often responsive to common anticonvulsant therapies. Seizures resulting from epilepsy in larger breeds (German Shepherd, St. Bernard, Irish Setter, Retriever, Husky, Malamute, and Old English Sheepdog) are among the most challenging to treat. They may be difficult to control with single anticonvulsants and often require a combination of anticonvulsants.

Due to the many possible causes of seizures, a full seizure workup is recommended. Seizures must be treated on the basis of their origin. For example, metabolic and toxin based seizures are often treated as emergencies with depressants or anticonvulsants but must ultimately be managed by correcting the specific abnormality. A full seizure workup will include blood tests to evaluate internal organ function. In addition, skull x-rays, a spinal tap to obtain cerebrospinal fluid (CSF) samples and pressure levels, or a CT scan or MRI may be indicated.

Treatment

Once the cause of an animal's seizures has been determined, a course of treatment can be selected. Treatment often involves the administration of medications, but occasionally surgery may be required. In all cases, the determination of the cause of the seizures is the first and foremost consideration when selecting a treatment plan.

If your pet is diagnosed with idiopathic epilepsy, we will advise you on a long term treatment plan. Medication will need to be given on a daily basis. Periodically, your pet’s blood level of anticonvulsant will be checked along with blood tests to monitor and minimize potential side effects.

Because we can treat epilepsy but not cure it, an occasional seizure is not unexpected while on anticonvulsant medication. We target our treatment plan to reduce the severity and frequency of seizure activity, not to necessarily eliminate seizure occurrence. Rarely, status epilepticus may occur. This is when many seizures occur in rapid succession without intervals of consciousness. Status epilepticus is an emergency situation and, if it occurs, your pet must be seen immediately by your veterinarian so that medications can be given to stop the seizures.

It is recommended that you keep a log of all seizure activity. Many times seizures occur at specific intervals or accompany specific stressful situations, hormonal cycles, or other unusual events. These seizure logs may allow us to alter specific doses of medications or to augment medications at peak times to better control seizure activity.