Advantage Blue For X-Large Dogs Over 55 lbs (25-40kg) - No Rx requiredAdvantage Blue For X Large Dogs (4 Pack) Flea prevention and flea and biting lice treatment. Kills fleas and biting lice on dogs One treatment prevents further flea infestation for four weeks Can use as a part of a treatment strategy for the control of allergy dernatitis Dog Size : Obver 55 lbs (25 40kg) Method of Administration : Topical. Part the hair on the back of the neck at the base of the cats skull until the skin is visible. Place the tip of