WARNING! THIS IS GROSS! My maltese is 10 years old. I have always used Frontline but for financial reasons, tried the Hartz assuming they are a reputable company. Everyone’s heard of them right? I applied the flea product to my dog as stated. I left on a cruise with my family the next day and did not see the results until 5 days later. I had no contact with my mother who was watching him due to no cell phone signal. When I got home, he had a lump on his back where it was applied about 3/4″ high off his back. It was black and flaky and disgusting. I didnt know if it was an infection or burned. I called the vet immediately and took him there only to learn that Hartz products are known to be toxic to dogs and cats and this is not unusual. My poor dog had to be shaven, all the way down through his top layer of skin. Now he has a patch about 3″ wide shaven with a gooey bloody gauge in his skin that needs ointment applied twice daily and antiobiotics orally. He is in pain and it also itches. I am appauled they are selling these products and getting away with it! I am very much interested in a class action lawsuit as well. My email address is [email protected] if anyone has information. They need to be stopped. It looks like there are enough of us little dogs to attack the big one! Poor pets. Just horrible!