My dog is covered for illness and I keep up with rountine care, testing, and vaccinations. We got our dog one year ago from rescue shelter and he was heart worm negative. I have kept up giving him Trifexis . With yearly updates, i found out he was positve for heartworms. My vet tells me that sometimes you can get a false negative ??? Pets Best tells me that heart worm treatment is covered on routine/wellness care ONLY and will NOT cover his heart worm treatment. I am sorry, my dog contacted heart worms when I did everything right and is no longer WELL. He is recoveing and will be looking for another insurance!!!!! My vet has given me some recommendations.