Do all of you give your dogs heart worm preventative, such as Heart Guard? I called the vet to get my dogs scripts refilled and they said they have to have a blood test first. I asked why, if they're on the medicine and never skip a dose, why do we have to do a blood test. She said that all dogs on the meds have to have a test every two years and dogs not on the meds have to have a test every year. So does that mean people don't give the meds, they just have the test done yearly? How safe do you think this is? I don't live in an area that has a high rate of heart worm cases. Do you think it would be safe to just have the test done yearly and skip the meds? It sure would be cheaper, but that is not my main concern.