My dad recently bought an older dog that has tested positive for heart worms. I’ve read about different treatments for this. My vet said to put him on a preventative because the test only showed three dots on it. We always gave our dogs 1/10 of a cc of ivomec bought at the feed store as a preventative but I’ve read this doesn’t kill adult worms. I also read it does but when they die it can kill the dog too. I know the vet can treat the dog but it is done with arsenic and can also kill the dog. So as y’all can see, I’m very confused…any help? Thanks