I've had my dogs on PetFriendly flea and tick preventative for years. I added my cats last year. I love that I never have to remember anything except to put the medication on them. I complete the tasks the day their shipment arrives and I always have. They've never missed a dose. I also love the packaging and treats they provide. However, my dog was recently diagnosed with lyme disease from a tick bite. Hopefully, we caught it in time without damage to his organs. He'll be on antibiotics for 30 days. I don't know if any flea/tick preventative actually prevents this...all I know is that my vet tells people that the stuff they sell in their office DOES prevent it. I am no vet or scientist. I'm just telling our experience.