I don't dose year-round, because, as the article says, the only reason for that in Northern states is because they think you're too forgetful to give heartworm prevention only part of the year, and I know I can remember. But I have seen dogs die from heartworm infection, and it's not nice. And I have seen no evidence that a drop of ivermectin every month is more dangerous than taking a chance on heartworms.
I do agree. I am not a fan of putting chemicals in my dogs, so I try to prevent it as much as possible. I live in Central Texas, so I have to do heartworm most of the time. I have been trying out different essential oils for flea prevention for my dogs. I am using a rosemary eucalyptus spray right now and hopefully it works as it gets hotter and hotter.