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Cat Seizures and Epilepsy 101

Reviewed by Dr. Celeste Clements, DVM, DACVIM on Tuesday, June 16, 2015
Posted June 16, 2015 in Cat Diseases & Conditions A-Z

Orange cat looking up

The term "seizure" is often used interchangeably with "convulsion" or “fit,” but what do all of these terms really mean is happening? A seizure starts as a result of abnormal, excessive electrical activity in the brain. According to Chelsea Sonius, of the Zimmer Feline Foundation, whether in humans or animals, all seizures:

  • Start as a result of these electrical misfires in a part of the brain called the cerebrum.
  • The abnormal electrical impulse spreads from cell to cell.
  • This unregulated activity in one region of the cerebrum causes increased activity in other regions, a phenomenon termed "hypersynchronous activity."  
  • The brain becomes uncontrollably "hyper excitable," which leads to seizures. Convulsions can then cause a cat’s body to shake rapidly and uncontrollably.

How can one cat seizure differ from another?
Epilepsy.com says, “Seizures may take many forms.” The outward effect can vary from uncontrolled, violent, jerking movements (tonic-clonic seizure) to a subtle loss of momentary awareness (absence seizure), which may go unnoticed by others. The syndrome of recurrent, unprovoked seizures is termed epilepsy. Seizures can be brought on by either primary brain disorders, or they may develop as a result of a process outside the brain. Conditions like low blood sugar, liver failure (when it leads to “hepatic encephalopathy”) or conditions that make blood thicker (as happens with high red blood cell or protein levels), are examples of processes outside the brain that may cause seizures. In addition, certain cardiac events look a lot like seizures, but don’t predictably alter the brain’s electrical activity in the same way. Temporary loss of consciousness (syncope) or collapse, associated with some heart rhythm disturbances, can be very hard to distinguish from seizures in some cases.

How common is a cat seizure?
Seizures occur in both dogs and cats, but occur less commonly in cats. Zimmer.com estimates that approximately 2% of all cats are affected by some seizure disorder.

What are the underlying causes of a cat seizure?
Seizures occur at all ages and in all breeds; however, older cats are more likely to be affected by a variety of underlying causes:

  • Tumors
  • Trauma
  • Infections

There is little evidence that seizures in cats have a hereditary component. Most cats with seizures will have some structural change in the brain contributing to the seizure disorder. Unfortunately, recent studies show that from 22% to 41% of cats had epilepsy of unknown cause; the neurologic work found no structural or blood-borne cause1,2,3.

What are the signs of a cat seizure?
Seizure activity in cats is often very violent, but can be quite variable. Common signs of seizures in cats can include:

  • Sudden bursts of activity
  • Aggression
  • Drooling (hypersalivation)
  • Facial twitching
  • Loss of consciousness and uncontrolled muscle activity (tremors, twitching, and convulsions)

If you are unsure if your cat’s behavior is a manifestation of seizure activity, a video recording of an episode may help your veterinarian make that determination.

Click here to learn about the benefits of videotaping for your vet.

How is a cat seizure disorder diagnosed?
The first step in diagnosing a seizure disorder will involve a thorough history from you, and a complete physical examination for your cat. Blood tests will help eliminate some (metabolic) diseases, but additional testing will likely be required to find the cause. A number of seizure disorders in cats are associated with frequently operable brain tumors.

Testing could include:

  • Spinal fluid analysis
  • Advanced imaging , such as MRI or CT
  • Electrodiagnostics (EEG) – limited to neurology specialists

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Mike has more than 35 years of experience in companion animal veterinary practice and is a valued member of IDEXX’s Pet Health Network team since 2013.