We almost lost a German Sheperd to heartworm about 6 years ago. After almost a week in the 'hospital' the vet told my husband all about the new heart worm medicine. It was an injection that they could give them, I think every couple of months. We had two Sheperds. It was a little expensive, but it was our babies. I wasn't there the day the vet was telling my husband about this. Living in south Georgia, where the state bird is a mosquito they couldn't live without. A year and a half later, after moving back to West Virginia, we thought that he had hurt is paw trying to dig in the frozen ground, cause he was always digging in Ga. Anyhow, when it didn't get any better after a week, and he wasn't eating anymore... well, to make a long story short, Chipper died from cancer. He had developed cancer in the leg where they gave him the injection. When talking to my husband about this, he said the vet had said there was a slight chance that he could develop cancer from the shots. As for Baby Girl, she mourned herself to death a few weeks later.
Go for the pills, not the shots unless they have changed.
