Heartworms are tricky - the Pet Wormer will remove them slowly without causing too much trauma whereas the prescription heartworm meds will kill them all at one time which releases a LOT of toxins at one time.

This is why vets will tell you that treating a dog for heartworms can kill the dog. It all depends on HOW MANY heartworms are present - if it is a small number - then the dog might live through the toxin overload - if the number is high - the overload from all of the worms dying at the same time will kill the dog.

This is also why slower is better for parasite removal in humans. Too many toxins released at one time can kill a person. (As in pork tapeworm cysts in the head.)

You can't tell how many are present - and this is why prescription meds are such a gamble. I would suggest doing the Pet Wormer double strength first - do it for 5 days - then wait 30 days and do it again. Then after 2 rounds of the Pet Wormer - you can do the prescription meds at half strength.

Let the dog build up his strength - then do more half strength prescription med.

Hu-Mana-Tea can also be given to dogs - it works the same as in humans in removing toxins.