My daughter got a 20 week old kitten from the local humane society, which cost us $90. We decided to keep it in the house, so I bought some Hartz UltraGuard OneSpot so we could keep the fleas away. After applying as directed, the cat became lethargic and just wanted to sleep. I thought maybe he was just getting accustomed to his new environment. I had to be out of the house for several hours the next day. When we came home, THE CAT WAS STRUGGLING TO BREATHE AND APPEARED TO BE ALMOST DEAD. I called the vet (after office hours) and he agreed to see the cat. He told us that the Hartz Flea Treatment has killed more cats than fleas. He gave him two shots and some oral medication. He told us to bring it back the next morning and we did. He gave it two more shots and more oral medicine. We have to go back in two weeks for more shots. He is one sick kitty. He has begun to breathe better but has to breathe through his mouth. He is still lying around and not wanting any attention. We try to get him up and he goes right back to his bed. I sincerely hope he starts coming around because Im really getting worried about him. This flea treatment has already set me back $150 and I will have to pay more when we go back in two weeks. I can’t believe this stuff is over the counter and so dangerous. I will never trust the name Hartz for anything ever again. I plan to spread the word. This product should not be on the market!