I actually don't have a dog, although I'm getting another foster greyhound in Feb. My cats are indoor only and haven't had fleas since I got them (and they were infested for a bit, advantage 2 did nothing but they were too young to get anything else. I also had to treat my entire apartment, twice
) but I have used comfortis, cheristin, and catego for them. I also brush them like 3x a week and haven't seen a flea in over a year, regardless of using products or not.
We've (by that I mean the vets and I pass this info along) been recommending nexguard for fleas and ticks and that seems to be working for everyone much better that vectra 3D. Or comfortis for just fleas. I think for heartworm we have been carrying heartgard and interceptor. Honestly a lot of people do not give heartworm prevention because I work at a nonprofit and they just don't have the money or aren't going to spend it on that. We do carry advantage multi to cover fleas and heartworm prevention but I know one vet doesn't like it and also it hasn't been working for fleas well at all. I honestly can't remember what product the organization gave me for my last foster greyhound but I think it was some sort of bulk thing they do. It was in the shape of a bone so if anyone knows what that is that would be great.