[anonymous]

No, I am not aware of any “natural” heartworm or flea/tick preventives that are effective.
Also, if the dog tests positive for heartworm, the treatment that works to save the dog’s life is very harsh. Same with Lyme disease, nasty disease if not caught early.

Some science based information you may find helpful here http://skeptvet.com/Blog/?s=heartworm
Nothing is being sold at that site, no supplements, no books, no miracle cures, no membership fees………