I gave my cat Hartz flea medicine because my dog has used it for years and has been fine. I bought the type for cats at the correct poundage. My morning she had puked blood and vomited large amounts. She couldnt jump and could barely walk. When she came up to me her facial expression looked like someone who was half dead. I called my vet and they stated that this brand poisons cats and that I needed to bathe her asap. So far she seems okay. She is not her normal self. She has slow reaction time and she is not as rough and playful. She normally greets me at the door and cant wait for me to hold her and this time she did not. When I picked her up she laid her head on my shoulder and was very still and her breathing sounded a bit wheezy. This is way better from this morning. I have an appointment with my vet in the morning.