Cat Seizures and Epilepsy 101

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.

To read more on this story, click here: Cat Seizures and Epilepsy 101

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Most Common Triggers That Induced Seizures in Cats

The United Kingdom-based charity International Cat Care reached out to veterinary specialists after receiving surprising complaints from cat owners: Their feline companions were apparently having seizures in response to high-pitched sounds.

A study of these cats revealed that the sound-induced seizures were more common in older cats, and the most common triggers were crinkling tinfoil, hitting a ceramic bowl with a metal spoon and tapping glass.

Mark Lowrie and Laurent Garosi, veterinary neurologists at Davies Veterinary Specialists in England, and Robert Harvey, a molecular neuroscientist and geneticist at the University College London School of Pharmacy, decided to survey cat owners about the phenomenon, which has been dubbed "Tom and Jerry syndrome," after the cartoon character Tom, who often responds to startling sounds with involuntary jerks. [Feline Fun: 10 Surprising Facts About Cats]

Hundreds of cat owners from around the world replied that they had noticed their cats were having seizures in response to certain types of sounds. Most owners' vets didn't know what was causing the seizures and didn't believe a sound had been the trigger.

In a study published in the Journal of Feline Medicine and Surgery, the researchers looked at data from 96 cats, including the type of seizure, how long it lasted and what sound appeared to trigger it. They found that some cats — like some humans — suffer from seizures caused by sound, known as "audiogenic reflex seizures." In the cats, certain sounds triggered absence (or nonconvulsive) seizures; myoclonic seizures, characterized by brief muscle jerks; or generalized tonic-clonic seizures, in which the animal loses consciousness and its body stiffens and jerks for several minutes.

Both pedigree and nonpedigree cats can have these seizures, but they were most common in Birman-breed cats. Seizures were also more common in cats ages 10 to 19, and the average age of onset was 15 years, the researchers said.

The sounds that triggered the seizures ran the gamut, including crinkling tinfoil (82 cats), a metal spoon clanking on a ceramic food bowl (79 cats), chinking or tapping glass (72 cats), crinkling paper or plastic bags (71 cats), computer keyboard or mouse sounds (61 cats), jingling coins or keys (59 cats), hammering a nail (38 cats) and the clicking of an owner's tongue (24 cats). Less commonly, cellphone ringing, Velcro peeling or a walk across a wooden floor with bare feet could trigger the kitty seizures.

Owners could sometimes prevent the seizures by avoiding these sounds, but that wasn't always possible. Louder sounds also seemed to make the seizures more intense.

The researchers have identified this cat version of sound-triggered seizures as feline audiogenic reflex seizures, or FARS for short. Future work will focus on the genetic basis of the disorder and how to treat it.

The epilepsy medication levetiracetam can be an effective treatment for managing FARS, and could "completely rid" a cat of sound-induced seizures, the researchers said.

"How wonderful to be able to go back to those worried owners who came to us for help with a problem previously unrecognized by the veterinary profession with not only an explanation for their cats' behaviors, but a way to help them as well," Claire Bessant, chief executive of International Cat Care, said in a statement.

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