I bought Hartz from Walmart for our inside kitten (8 months old…probably a cat by now). I put it on her and she ran away per usual. An hour later she is lethargic and lifting her legs (looks like she had tape on her feet). She couldn’t hold her head up and wasn’t playing. (She plays 90% of the time and we have developed a love/hate because of it. Five AM hits and she’s ready to go. Every. Morning.) This medicine is actual poison. It put my kitten on her behind and she got convulsions. I was unnerved and bathed the medicine off her (after googling Hartz) and she is ok. It was on her for 9 hours. I will never use this again and I will tell every person I know to never use them.