Don't buy any with Bromethrin in it, that's the toxin that attacks the brain and is impossible to cure. The first symptoms are twitching and seizures, then they just start purring and fading until they slip away. The vet said they have no idea what's going on so they'll all react different. My pregnant cat screamed whenever we touched her and she always loved attention, but my Grey one (who never ever liked to be petted) stopped walking and just stood in the lawn, meowing and purring nonstop, and wanted to be held. The other two I didn't get to observe their symptoms, I just found them dead.