Sorry on accident I posted this in the introductions section. So I wanted to repost it. I have a 7mo old and a 3 mo old mastiff I have the 7 mo old on Heartguard. But I have had people tell me they use Ivermectin for horses or swine I know it goes by body weight so it would take alot less. My question is has anyone used this to prevent worms. I guess it is alot cheaper but I don't want to take a chance either.