I just bought a dog and I need to pick a Heartworm medicine for him. Which is the best choice? Which is more effective? Which is heathiest? Friends are recommending Heartgard. Is that a good recommendation?

Hi, Martin,
I spent all my working life in the UK, where heartworm is not a problem, so I have no immediate experience.
Any modern medicine which specifically is recommended for heartworm prevention should be OK. It is absolutely essential that you follow the instructions about frequency of dosing - it is much better prevented than waiting till the dog is infected - there is no effective treatment.
Walter