I was almost sick reading this site realizing that my poor cat might have died from my stupidity, but am so glad I did find this. I bought Hartz Ultra Guard One Spot Treatment for cats last night and applied it to my cat. Shortly afterwards, he began trying to lick the area and scratching it. A few hours later he appeared foaming at the mouth, so I rushed him into the bath and used Ivory soap to get the stuff off him. Thankfully, he is okay and eating and behaving normally. I SO wish I had checked this out on the web before using it, but I stupidly trusted Hartz. I bought this at Atlantic Superstore in PEI Canada and am going to write and beg them to stop carrying it; also, I am going to make sure I post notices at the Humane Society and anywhere else I can think of to save other pets from this horrible fate. From me and my sweet little boy Billy, thanks to everyone else who took the time to post here to let others know about the dangers of this product.