Hi. My husband and I bought hartz went home and applied it to our two cats. Our one cat tried to lick it off and starting foaming at the mouth and freaking out. We immediatley washed it off ofher. She now has a bald spot in the location where I applied it. My other cat now has a streak of bald and spotted with blood down her back and is still afflcited by fleas. We are taking them to the vet today. I spoke with them on the phone and they said the same thing that everyone else is saying, Hartz kills cats.