I live in a very small town, and my vet has his own office, working alone with 2 assistants. He's too small to carry large supplies of everything (advantix, frontline & promeris). He did say if promeris doesn't go over very well, he will stock up on advantix again; and I can also buy advantix elsewhere. My vet just thinks promeris might be better because it works longer that advantix. I'm still on the fence; just getting different opinions.