I put Harts on my 1 year old dog and one week later we had to take him to the vet because he had what looked like scabs on his back. At first the vet thought it was hot spots, but after shaving him, realized it was not hot spots. He told me that it had to have been from the Harts flea and tick medication i had put on him a week prior. His skin had completely died and fallen off. it was about 8 inches down his back and about 3 inches across of just pure flesh. I was devastated when i saw my dog. I could not believe that this could happen with such a well known product. so i have sent a package with vet bills and pictures to the company and they are “Supposed” to get back to me. I have not heard from them in almost 4 weeks. i think i am going to send this story with pictures to the nearest big newspaper and my family lawyer. Hopefully it will all work out one way or the other. if anyone has any information please contact me at [email protected], subject Hartz.