I've been using Frontline on my pets for several years. I was reluctant to do so at first, because I'm not really comfortable with something that gets into the system and kills fleas and ticks from within. It just doesn't sound all that safe to me; but my stepson, who is crazy mad for all animals and who worked for a vet at the time, advocated so strongly for Frontline that I decided it must not be so bad. My pets have never seemed to like having it applied. Two of them (one dog, one cat) always resisted and behaved as if it was unpleasant for them for at least a day after application. It worked, however, keeping the fleas and ticks off the pets and out of the carpet and bedding inside The House. The thing is, I don't think it's working so well anymore. It seems like it's no time now after an application that I notice the fleas and ticks are back. I don't know if the Frontline formula has been changed or if the animals have built up a tolerance, but I'm thinking I need to find another solution to fleas and ticks on my pets.
I do use it, however I am also a little resistant to do so. I will only use it if I find ticks or fleas on my dog, if not I will not use it as a prevention. I know everybody says that it just kills and harms fleas and ticks, however the smell is so strong and my dog will sneeze a couple times after I put it on that I don't trust completely that it's not harmful for dogs as well.
I use natural preventatives in the yard (D-earth) and in my carpets. I also use a herbal based spritz on the dog and myself that is supposed to discourage fleas and ticks if we'll be outside of the yard. If we're somewhere that I see fleas or suspect fleas, I give my dog a dose of capstar - which is a pill that kills adult fleas on the dog within 4 hours (we go through about 6 of these per year). Rarely (like 1-2 times per year) I give my dog a dose of frontline if these other methods don't work. But I can't see poisoning my dog every month all year long when it's not necessary.
We have used and are currently using Frontline for our dogs that have ticks. They seem to be effective in repelling them, although since I do not search our dog's fur for ticks, I wouldn't really know if they can be immune to it in the long run.