I agree that we should be using alternative things for our pets too. The alternative things really do work and offer our pets protection.
I am a holistic dog breeder and a lurker here for many years, but today I had to sign up so I could respond to this.
Heartworm preventative is very dangerous to our dogs. It is also a huge money maker for a vet. Please do your research before you use this, flea preventative or vaccines for your pets. You cannot accept what a vet or dr tells you just because they went to school. You can sometimes get a diagnosis from them but always research it. My website is full of information and I have a page on Heartworm too.
I have been breeding for about 10 years and have been NO doing vaccines for about 3. None of my puppies have contracted anything or my adults. However, we have had puppies die after immunizing them. My adults, even though do have to get the rabies vaccine by law, NEVER ever have gotten sick.