about 2 years ago, unknown of the hartz product hurting cats, i bought some because i had fleas. i had 3 cats. i applied it on all 3 of them, on the box it said apply a thin line from base of skull to the base of the tail, that did not sound right to me knowing they could lick it, so i only applied it to the base of their skulls. several hours later, punky (she was almost one at the time) started acting strange, just laying around i thought she was just tired or something… but then she would not get up, eat or take interest in anything i was doing. i had no idea what harm could have happened. i still didnt think much, just thought she had an upset belly or something, but then i got her up and she couldnt even stand, was all wobbly and incoherent and could not even meow more of a squeak. so i freaked it was very late at night and i knew i couldnt get in a vet, i did not have a car at this time and there was nothing i could do. so i called my mom, she said that she could be having a reaction to the hartz flea spot and to wash her with a mild soap, nothing with flea control just soap. so i did and she started looking a bit better a couple hours later. the next day i got her to eat canned food and she started walking a bit more and by the time i called around trying to get her in somewhere she was looking much better. i cant believe what this stuff can do, its horrible. i know my story is minor compared to the results of alot of you, and i do feel all of your pain. my pets are my kids, and if anything happened to them i would be a mess, like losing a human child. i warn everyone with pets not to use any hartz products and pray that no one encounters any harm to their pets. my thoughts and prayers are with you all. i only use advantage now with no side effects at all. i like the rest of you wish i would have found all this info out a long time ago and never thought i was putting them in danger i was only trying to help them.