Finnigan is not on a heartworm medication and the vet has never discussed this with us. I meant to ask when we took him in for his one year shots a few weeks ago but we had to see a substitute vet as ours was out of town and I was so busy bringing her up to date on Finn that I completely forgot to ask her. My family has never had our dogs on heartworm meds when I was growing up and I’ve been told before that it's not a big concern in Arizona (at least in the Phoenix/Scottsdale area). I admittedly know nothing about heartworm medications and I don't want to put him on unnecessary medications. I was even wondering if there was a holistic approach. I'm hoping all of you can share your knowledge and offer advice to help me make an informed decision. Thanks!