My cat has recently died. He was a year and a half. I wasn't sure if he was poisoned or not but my neighbor said he might have been poisoned with Anti-Freeze.. When he died his eyes were heavily dialated and he was having seizures on and off. Are those side-effects of poison? We let him out half and hour earlier before this happened, then when we let him back inside he started acting like weird (twitching on the ground, unsteadiness, hissing, dialated eyes, ect.).