Usually one every two or three months, at least that I know about since I have no way of knowing if she had them when we weren't at home. Basically, she would seize up, fall over, and would be totally gone for 10-15 minutes. All I would do is hold her tight against me until it was over so that she wouldn't hurt herself. As far as I know, the side effects from the medication are potentially more harmful than the seizures themselves. She seemed to do fine right up there til the end, and then, she was 15, so it was always just a matter of time anyway. Enjoy every moment. Dogs are awesome and one of the few beings I know of that are capable of unconditional love pretty much from day one.