Feline seizures can be caused by many different diseases that cause the cerebral cortex (or at least part of the cerebral cortex) to function abnormally, leading to a seizure. This may result from diseases that actually cause changes in the brain itself or from diseases that originate elsewhere in the cat's body but affect the brain adversely by changing the way the brain's metabolism works or changing the electrical functions within the brain.
Intracranial Causes of Feline Seizures
Intracranial causes of feline seizures are those that originate in the brain itself. These may be structural or functional in origin.
Diseases that can cause structural changes in the brain that can be responsible for seizures include:
- brain tumors
- infectious diseases such as feline infectious peritonitis (FIP), toxoplasmosis, feline leukemia (FeLV), feline immunodeficiency virus (FIV) and cryptococcosis
- immune-mediated diseases such as immune-mediated encephalitis
- congenital disorders such as hydrocephalus
- trauma to the head
Functional intracranial causes of seizures generally refers to idiopathic epilepsy. Idiopathic epilepsy is defined as having recurrent seizures for which the cause is unknown. Essentially, idiopathic epilepsy is diagnosed by ruling out all of the other causes of seizure activity in the cat.
Idiopathic epilepsy is a common cause of epilepsy in the cat but investigation into other causes is always called for before a diagnosis of idiopathic epilepsy is determined.
Extracranial Causes of Seizures in Cats
Seizures in cats are not always caused by disease within the brain itself. Sometimes diseases that start elsewhere in the body affect the brain and cause seizures. These diseases are known as extracranial causes. Extracranial refers to being outside of the head.
The most commonly encountered extracranial causes of feline seizures are:
- thiamine deficiency in the diet
- hypoglycemia or low blood sugar levels
- hepatic encephalopathy - advanced liver disease which affects the brain. A portosystemic shunt is the congenital disease which most often causes hepatic encephalopathy in young cats.
- electrolyte imbalances such as low calcium or low sodium blood levels
- poisons such as antifreeze (ethylene glycol), carbamates, organophosphates, lead, metaldehyde (slug bait), strychnine and others
Seizures are usually not the only symptoms seen with the extracranial causes of seizures in cats. Your cat may exhibit a variety of other symptoms, depending on the condition involved.