One week before a scheduled vacation (Sunday) I used Hartz Flea and Tick Treatment drops on my dog. Within 24 hours my dog stopped eating (Monday). The next day (Tuesday) he was so sick I thought he was not going to make it through the night. I did not know what was wrong. I made an appointment for the vet but couldn’t get in til Saturday. The next day (Wednesday) he still was not eating. I gave him a bath. The next morning (Thursday) he ate a little bit. The following day (Friday) he ate a full meal. I thought he was getting better. Saturday he seemed back to normal so I cancelled the vet appointment as we would have missed a friend’s wedding. That night he lost control of his back legs. It lasted about 10 minutes. The next morning it happened again. He lost control of his whole back end for 30 minutes. I called a vet who said dogs sometimes have this sign when they are dying. We were leaving on vacation that day so I made the painful decision to put him down. I called my kids. My son asked if I had done anything different the previous week before it started. I told him about the new brand of flea and tick treatment I had used. He looked it up and saw that all those symptoms were described by others who had used it. I immediately gave him another bath with Dawn Soap and cancelled the euthanasia. The next week he continued to improve except he was itchy. Then he started to lose the hair all down his back where the product was applied. The vet did a bunch of testing. I returned to the vet a week later where whey did bloodwork. His liver enzymes had quadrupled. Liver damage was another symptom described by others. The vet put hi. On medication to try to heal his skin lesions. I have been on an emotional rollercoaster and a bunch of vet bills. Do not use this product. I almost lost my baby and he went through hell.