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November 24, 2011


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This is a very informative article. This shortage is unbelievable but at least they’re working on more alternatives (Trying to be positive)*. I have heard that now there is a product that both kills and prevents heart worms called HWF (Heart Worm Free)- this seems to be doing the best as a substitute for right now.


This product has no proven effectiveness.

I have spoken with veterinarians who are well-known experts on holistic and alternative medicines, as well as those interested in Chinese traditional herbal medicines.

The product is considered to be what used to be known as "snake oil", i.e. bogus.


Thank you Dr. Mobley.

This dog is also not neutered and the veterinarian does not want to neuter until the dog is free of heartworms.

We have been treating for doxycycline + ivermectin for 3 weeks so time to make a decision. I am going to the vet on Saturday and will discuss it.

I thought this study stated ivermectin + doxycycline killed 78.3% of adult heartworms after 36 weeks, but it states "reduction of adult heartworms" so perhaps they are referring to physical size reduction, not reduction in actual number.


Thank you for a good discussion of an important issue.


Hello again, Eric,

I am not a heartworm researcher, but do try to relay correct and current information from experts I respect.

We pre-treat dogs with this regimen, as I said before, and they still have the heartworms. It is a good thing to do, but I certainly would not depend on it clearing the dog of adult heartworms (without the Immiticide).

Thanks for reading and writing.


We ultimately treated with Immiticide and the dog has now tested free of heartworms.

At least, free based on the SNAP 4 DX.

It was a long and hard ordeal for the dog and with all the confusing information about heartworm and prevention and treatment it seems impossible to know the best choice. The person who was fostering him is a nurse and she told me more than once she thought he was going do die during recovery.


Glad you've had a good outcome. Thanks for writing.


I live in an urban area of SE Michigan. I adopted a healthy young (about one year old) #80 dog that initially tested negative for heartworm (December), and placed her on monthly ivermectin. Nine months later, she tested positive for heartworm antigen x 2 different test types, no microfilaria. She had no symptoms of disease. The vet was very hostile to the idea of treating her with Doxycycline 20mg/kg/day in divided doses for one month, and continuing monthly ivermectin preventative. The vet recommended Doxy, prednisone, imiticide, overnight observation for at least two nights, lab tests, and chest x-ray at an estimated minimum cost of $1300. I elected to continue ivermectin and a month of doxycycline. My dog has tested negative for heartworm, two and a half months after completing treatment. We did not crate her, but she was confined to the house and a small area of the yard. A lot of things went into my decision to treat with doxy/ivermectin including having a large dog, a young dog, an asymptomatic dog, a dog who likely had a low worm burden, and a price tag of $100 versus $1300. There have been several studies that have looked at treating heartworm with doxy and ivermectin. While I am aware of concerns with heartworm death causing inflammatory and obstructive complications, (I had a dog die from renal failure after treatment for heartworm twenty-five years ago, not originally my dog, but a stray I picked up off the streets of Detroit) and with concerns about developing resistance to ivermectin and/or doxycycline, I do believe this is a reasonable alternative treatment for selected dogs. Please comment on why veterinarians are not willing to even consider this as an alternative treatment option.


Hello, Lisa,

"Please comment on why veterinarians are not willing to even consider this as an alternative treatment option."

Because it doesn't work. It doesn't kill the adult heartworms. You affect them temporarily, so that there is less antigen (the protein from the female heartworm reproductive tract, which is what the antigen test detects, versus actually seeing the microfilariae/babies in the blood) in the bloodstream and the test shows negative. The worms are still there. You haven't killed them.

They are weaker, they will be smaller and easier to kill, but the effect only lasts about 3 to 4 months.

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