I think it's important to remind everyone NEVER to give more than the dosage recommended in the instructions. I saw the results of that at my vet's once- a poor beautiful maramelade tabby cat in a cage having horrible convulsions due to being over-dosed with one of these products. She was literally poisoned and the vet said she had been convulsing for a day and a half. I asked about the poor kitty later, and she did recover but came close to death. That was from Hartz Mountain flea/tick meds.- though I'm sure an overdose of any brand might produce the same results.