ProHeart 6 is coming back. Good thing? Bad thing?

Bad thing. I wouldn't ever trust that company. I live in Canada, and as far as I know, we don't have anything like that available here. But I have no problems with applying my dog's preventative once per month. That's why they have calendar stickers in the box, so you don't forget to give it. I can see why a 6-month preventative in one application would be dangerous.