Hi, I used the Harz flea and tick topical medication on my dog, back in September. I went to brush his coat the next week, and a patch of hair came out. I then checked his skin and every were I had put the medication on his back clunks of hair came out. I took him to the Vet and they had to give him medication, and now his seems to be coming back slowly. I can’t believe that the would be marketed for use, when it is this strong and harms the dog.