I use Bravecto, get it from Vet, kills Fleas and ticks, got 3 Rotties and a German Shepard. they stay outside all day and come in at night, never have any fleas or ticks. It is a chew able, no problem getting dogs to eat. Cheap way to get fleas out of the house, get some small lamps and some bowls of water, put lamp and water in room, turn on light , they will jump toward light and fall in water and drown. works good! Also close up house and set off flea bombs,
