I used Hartz flea drops on my cat Hobbes 3 days ago. He is 8 years old and a very healthy, fat cat. He has never been sick before, always healthy. Lastnight I was watching tv and he jumped in my lap, I was tired and sat him beside me because I didn’t want to pet him right then, he rolled over and started shaking violently and eyes were rolled back in his head. I grabbed him and ran to the bedroom, I woke my husband up and said Hobbes is dying! My husband woke up and started blowing gently in my cats nose – Hobbes came out of the seizure, I dont know if the breaths helped him but I assume they did. He was still shaking but not bad like a few minutes before. His mouth, whiskers, jaws and both front paws were still twitching, I said to my husband, could that flea medicine have made him sick??! I signed online and typed in hartz seizures on dogpile.com and page after page came up. I knew if I didnt do something to calm him he would be dead within hours if not sooner. I had a xanax (like valium) in the closet and pinched off some of it and put it in his mouth, I had a dropper and put water in his mouth so he would swallow. It took another 10- 15 minutes and he calmed him. He even ate some food and drank water on his own right after that. He is very tired today and feels bad I know. I gave a little more of the pill to him this morning and I think he is going to make it. I have seen a twitch or two today but nothing like lastnight. I stayed up with him until 4 this morning. It all lasted about 3-4 hours from the violent shaking that lasted about 2 minutes and then the tremors and twitches for about 3 1/2 hours. I am so sorry to read that this medicine is made and sold to unknowing victims like me. Who would think that trying to help your cat could kill him?