@Jenn H,
I agree with the above post. In my experience the natural stuff does not work. The fact that some animals test heartworm positive even with preventatives (vet prescribed) and annual blood testing, just shows you how serious this thing is.
An acquaintance of mine just went through this with a puppy he adopted from a shelter down South, the pup initially tested negative. Heartworm took a few months to show up (he was on heartworm preventive), the pup required aggressive treatment, so far he is doing well.
The vet thinks the dog was positive when he arrived in our area, just took a while to show up.
