I recently adopted two cats from our local animal shelter. Because the second of the two had been an indoor/outdoor cat, I decided to treat both with a single-dose flea treatment before confining them to being indoor-only cats. I carefully read the directions and planned to apply the medication during a time that I would be there a fully day to keep watch of the animals. About a half of an hour after applying the medicine, the first cat starting losing the hair at the base of its neck. I realized that she was having a reaction to the medicine and quickly washed it off with soap and water. I checked the second and she seemed fine. After a few hours I realized that I hadn’t seen the second cat around and went in search of her. She had found a hiding space in the drop ceiling of our basement and refused to come out. When we finally removed enough ceiling tiles to climb up and get her down, she was disillusioned and docile. She had lost nearly all of her coordination and balance and had trouble walking and standing. She also had tremors and would shake on occasion. I repeatedly washed the medicated area and gave her a lot of fluids but it took 3 days before she was herself again. After telling many people my story, I heard many other stories very similar to my own. It was then I realized that they all had one common factor… Hartz flea medication. I warn anyone out there against using this medicine on their pets. I know it is convenient since it is sold in many discount and grocery stores but it is dangerous. Please take the time and consult your vet about a safe flea medication.