Unfortunately I didn’t read these reviews before I purchased flea products at my local Petsmart. I decided on the Sentry XFC flea drops that go on the dog’s back. I have a dachshund that weighs 28lbs so I bought the appropriate weight size package. Within 4 hours of putting the drops on him he developed nervous twitching of both ears and his back. He twitched as often as a person blinks. We washed him and hoped for the best since it was Sunday night and the vet was closed. My husband carried Otis to the vet first thing Monday morning and she said she didn’t recommend those products. She gave him a shot of atropine and benadryll. Otis is now recovering from the twitching but he is extremely lucky to be alive. He had a very mild case compared to some of the other stories on this blog. I am so thankful to have my dog! I would hate to lose him over something like that. I intend to visit Petsmart and get a refund on that product. I can’t believe they sell stuff like that.