Comfortis flea treatment for dogs is the first flea control treatment approved for use by FDA. A chewable beef flavored pill specifically being provided to dogs once in every month. After the dog takes in the chewable tablet, fleas that sucked the blood of the dog are immobilized. The grown up fleas that were infesting your dog is paralyzed and will eventually die. Any new fleas which may infest your dog would suffer a similar fate. But it will be ineffective next to the flea larvae and pupae. But once they are born and grow to be adults, they will also be killed.