First off, I want to say that I am so sorry to those who had terrible incidents. My pet and I were very lucky that nothing terrible happened, but I wanted to post my experience somewhere just so one more voice about this product that DOES NOT WORK is heard. I used Hartz on my golden retriever for almost a year. I was trying to save money and saw it in the grocery store. I thought- why not? It DID work during the cooler seasons. However, 10 days ago I used it on her again and noticed that she was itching like crazy- no fleas though. That changed a few days later. She has fleas all over her and it irritated her skin. She’s miserable and my intent to save money went to crap. I took her to get bathed and dipped last night, and today I am taking her to the vet to buy more medicine and get something for the skin irritation. Grrr. I found out about this site and other stories FAR WORSE than mine. I know we were lucky in this, but again I wanted to simply voice that here is another case where this product did not work. I wish I would have bought the good stuff from the beginning! Good luck to all.