The important thing is to keep the cat from falling and hurting itself. As long as it is on the floor or ground, there is little chance of harm occurring. If seizures continue for longer than a few minutes, the body temperature begins to rise. If hyperthermia develops secondary to a seizure, another set of problems may have to be addressed. There are many, many causes of seizures.
Epilepsy is the most common and of least consequence to the cat.
The other extreme includes severe diseases such as brain tumors. Fortunately, most are due to epilepsy. When a seizure occurs, your vet will begin by taking a thorough history concentrating on possible exposure to poisonous or hallucinogenic substances or history of head trauma. These tests rule out disorders of the liver , kidneys , heart , electrolytes, and blood sugar level. If these tests are normal and there is no exposure to poison or recent trauma, further diagnostics may be performed depending on the severity and frequency of the seizures.