I have two dogs and a cat. I have used Frontline for years as I live on the beach. This year I have battled fleas all summer. I guess we have super fleas that have developed a resistance to Frontline. I called the 800 number on the box and was given a complete run around. Then they wanted a receipt (who keeps such things) obviously a way of not refunding my money. I offered to return the unused product that would not work. DO NOT USE FRONTLINE, THE COMPANY IS OUT TO ROB YOU BECAUSE THEIR PRODUCT DOES NOT WORK.