Fleas have been horrible and for the past 2 months I have used Frontline on my dog and 2 cats. A couple of weeks after the second application I noticed no relief for the cats. So I sprayed them with Hartz Ultra Guard Plus. For the next week everything seems fine then I noticed my male cat acting very lethargic and just not being his usual self. A very weak meow, not much moving around and not eating or drinking as usual. Because him and his sister are diabetic I take him to the vet yesterday. He noticed the fleas and I tell him what all I have used. He pulls down a container of the Hartz ( an older bottle) and points out the statement that Hartz is “hazardous to humans and domestic animals.” This infuriates me that Hartz is able to sell something when it is ‘hazardous”. It should be removed from the store shelves! I am still waiting for the results for my cat and I am praying that he will be okay and that his sister who is also not eating much will be okay also. I will be spreading the word via facebook and twitter about this product.