I had bought the flea and tick treatment for my four dogs and I noticed that the dogs didnt act right after I applied the treatment they would vomit. But I NEVER would have expected what i saw on my dogs neck it made me sick and I felt so bad. I took my dog to the vet. After the vet seen the damage on his neck she knew instantly what it was. She called it a chemical burn. The cost of using a cheap medicine is unreal. My poor dog is in so much pain i want to cry with him. Hartz should be banned from selling this product. I have pictures to show what it did too him.