We ran out of frontline, so my husband bought what he thought was reputable – the hartz ultra guard pro for cats. Two cats had no noticeable reaction, but the third was twitching immediately. She continued to act funny and I was watching her. I found this website and immediately bathed her. She calmed down considerably after drying off. I then took the remainder and threw it away. I told my husband we would never buy any hartz products again, and got the other two washed off. I’m horrified that these products are allowed to be sold, but I’m glad I saw this website and probably saved my cat’s life.