Zonisamide is most often used in pets as an add-on therapy for treatment of epilepsy. Epileptic seizures are ones that occur from an overexcitement of electrical activity within the brain. In idiopathic epilepsy, there is no known cause, though sometimes outside triggers, like stress or loud noises, may be connected.
Seizures may also be caused by a lesion within the brain, like a tumor or inflammatory mass. A previous trauma that led to damage of brain tissue may also contribute to a seizure disorder.
Like all anticonvulsants, zonisamide may be used in any of these cases where seizures are occurring, as a way of reducing their likelihood to occur by quieting the electrical overactivity within the brain by different mechanisms.
However, different anticonvulsants have different mechanisms of action and different degrees of efficacy. While zonisamide may be used in the case of any seizure disorder, it is most often used in cats as an add-on or secondary choice to help with seizure control.