Hartz sucks bigtime. They have so many lauswits against them and more are always pending (google their name and lawsuit’, it’s sickening).Their medications’ are not controlled by the dose or strength, they’re not manufacatured correctly they’ve poisoned thousands of dogs and cats. The FDA had a suit pending on them to pull ALL their wormers and flea/tick meds off the shelves by a certain date and the Hartz company did all they could to fight it, got a hold put on it so they’re still pumping this garbage out for people to buy.ALWAYS be safe and get your meds from the vet.