As a flea preventative, I purchased a Hartz Flea collar for my 12 year old cat about 45 days ago. For the last two weeks I noticed he didn’t seem to have the same pep in his step. I knew he did not feel well and tried to keep his as comfortable as possible. Sadly, I never noticed until last night what the effect the flea collar was having on my cat. I noticed blood all around his neck and under his chin. When I removed the collar he had no hair where the collar had been. Tragically, the flea collar and the raw/bare skin was covered with fresh blood, brown blood and dried blood. No telling how long he had been suffering. I really feel like a terrible pet owner that I never noticed be now. I just never dreamed that something purchased from a well-known company would be so harmful to my animal. I guarantee my cat is not an isolated case. Shame on them for marketing such a harmful product. I will NEVER purchase a Hartz product ever again. Furthermore, I will spread the word.