Vectra for Cats & Kittens Under 9 Lbs 3 Dose by Unknown Can be used on cats as young as 8 weeks of age. Fast acting. kills fleas in 6 hours. Fleas do not have to bite. Quick drying and non-greasy formula. Convenient topical treatment with patented applicator. Kills fleas that may cause flea allergy dermatitis(FAD), anemiacause, may transmit disease, including bartonellosis, tapeworm and tularemia. Each monthly dose controls development of all flea stages; Prevents, controls and stops flea infestation and prevents re-infestation.