There is no “Natural” or “Holistic” Heartworm Prevention or Treatment Proven to be Safe and Effective

Much of complementary and alternative medicine (CAM) is offered either as an addition to conventional, science-based treatment or in situations in which conventional therapies are unavailable or ineffective. This doesn’t excuse offering treatments that haven’t been properly tested, and it doesn’t mean such therapies can’t do harm. However, such an approach at least avoids the harm that can come from delaying or rejecting effective treatment.

However, sometimes CAM providers actually believe their practices are an appropriate and effective substitute for conventional medicine, even in the case of serious disease. This attitude is truly inexcusable when, as is usually the case, there is no sound evidence to support the belief and when irrational and inaccurate denigration of conventional treatments is used to scare people away from medicine that could really help their pets. One of the most egregious examples of this kind of irresponsible medicine is the promotion of “natural” or “holistic” methods for preventing and treating heartworm disease in dogs.

Heartworm disease is a parasitic infestation transmitted from infected dogs (or other animals) to uninfected individuals by specific kinds of mosquitos. It is, of course, most common in areas that have both a reservoir of infected hosts and a population of the right kind of mosquitos. In the U.S., heartworm disease is quite common in warm, humid regions, and transmission often varies seasonally with the mosquito population. Heartworms can cause devastating, often fatal disease.

Fortunately, there are safe and effective medicines to prevent heartworm infestation. While all medications have risks as well as benefits, the risks of these preventatives are well understood and very, very small. Certainly, in areas where heartworm disease is endemic, the risk of preventatives pales in comparison to the risk of the disease. So despite the often hysterical nonsense about these “chemicals” and “insecticides,” the real facts are clear: heartworm prevention is safe and effective and far better for your pet than getting heartworm disease.

If your dog is unfortunate enough to become infected with heartworms, there are effective treatments. The risk of treatment is, however, significantly higher than the risk of prevention, though in most cases still far less than the risk of leaving the disease untreated. The American Heartworm Society (AHS) has a thorough discussion of the pros and cons of different treatment options, and working with your veterinarian you can almost certainly cure this disease and minimize the risks of treatment.

The AHS is also very clear about alternative therapies for this disease: “No “natural” or herbal therapies have been shown to be safe and effective prevention or treatment for heartworm disease.” And fortunately, many proponents of alternative therapies also recognize that no CAM therapies have been shown safe and effective for preventing or treating this disease. The most popular veterinary herbal medicine textbook states, “The authors do not recommend substituting an unproven herbal formula for effective conventional therapy.” Even as radical a proponent of alternative therapies as Dr. Karen Becker at grudgingly agrees that,treatment for heartworm infection is one area where conventional veterinary medicine offers valuable options [and] is preferable to leaving the dog untreated, or using unproven, alternative methods that may have no effect or even be harmful.”

Unfortunately, there are still plenty of unscrupulous companies, and sadly even veterinarians, willing to exaggerate the risks of conventional prevention and treatment and claim that unproven alternatives are safe and effective. Below is a long list of sites promoting unproven methods of preventing or treating heartworm disease. None of these have been demonstrated to be legitimate or reliable, and trusting your dog’s life to any of them is a dangerous mistake.


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86 Responses to There is no “Natural” or “Holistic” Heartworm Prevention or Treatment Proven to be Safe and Effective

  1. v.t. says:

    Thanks so much for this article, skeptvet!

    Perhaps every state veterinary practice act should require an overhaul with strict language about CAVM in treating such diseases as heartworm (in addition to vaccination, etc) – or better yet, legal and enforcement ramifications for not complying.

    I hope I’m still alive when laws change (or in vet med, are actually enacted) allowing for swift and harsh consequences for these alt med pushers.

  2. Narda Robinson says:

    You missed one that offers creative choices:

  3. cassandra says:

    It’s a big, big shame that these unscrupulous people are suggesting these herbal remedies There is loads of dangerous advice over the internet and many suggested by non-professional or people pretending to be vets or experts. Please, please, please people beware of this unethical advice!

  4. Dr. Raja Zahid Khan says:

    Natural medicines providers are developing a desperate claim of being very effective in various diseases and are abundantly and randomly present in pakistan market. But the problem is not only from the producers but from practicing veterinarians too. Vets commonly prescribe these preparations despite their efficacy and authenticity thus leaving various lacunaes for para vets and common users.

  5. skeptvet says:

    Yes, this is a problem everywhere. Veterinarians are fundamentally clinicians, not scientists, and their focus is often on trying to intervene regardless of the reliability of the evidence for what they are doing. They often do not really understand how to evaluate a therapy and think that anecdotes and their own experiences alone are adequate to show something is safe and effective. Clearly, better education of veterinarians in this area is needed.

  6. Mike Loshe says:

    Thanks for the share. Pretty alarming to hear of vets telling people bad information. When I asked my vet about herbal prevention he laughed and told me just to use heartgard or another preventative heartworm medication. He told me that while herbal providers claim to be effective, there is absolutely zero evidence to back them up as of now.

  7. I agree with everything you say but do think you should have ‘nofollowed’ or broken the link to avoid giving any ‘link juice’ to this long list of sites – no reason to give them a boost!

  8. Todd Allen says:

    Very good responses to this article. It has been my experience that anything that purports to heal naturally is generally suppressed by the big guys that make the money from their “synthesized” versions. Everybody replying to this article MUST know someone who has benefited from a natural remedy no? My vet came right out and told me in a joking-kind-of-way that too much natural recourse knowledge of the general population would put many medical specialty practitioners out of business.

  9. skeptvet says:

    Yes, that’s a common, and totally worthless argument. If simple, “natural” remedies were readily available and anyone could find and use them, why did we never acheive a life-expectancy greater than abotu 40 years or an childhood mortality rate under about 50% until we began to apply science to nutrition, sanitation, and healthcare? Who was supressing those cheap, effective natural cures before scientific medical practitioners? You thnk everyone knows somebody who has benefitted (or, to be accurate, who believes they have benefitted) from a natural remedy? Leaving aside the meaninglessness of the word “natural” here, what you so blithely forget is that two generations ago, everyone knew somebody who had lost a loved one to tuberculosis, rheumatic fever, polio, trauma, or malnutrition. Now it’s hard to find someone who’s had that experience. Only a total ignorance of history can explain your point of view.

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  11. Fae says:

    I am usually very skeptical about “natural” medicines and their effectiveness and generally trust what doctors and vets say. Normally I would agree with this article without question. But it changes when you have a dog who is sensitive to the medications in typical Heartworm drugs.
    I have a 2 year old Australian Shepherd who tested positive for a common gene mutation found in herding breeds that causes his body to process Ivermectin, Selamectin, Milbemycin, and Moxidectin, all drugs found in Heartworm pills. Instead of processing the drugs by sending them throughout the body, they are sent to his brain and too much exposure can cause serious problems like strokes. Apparently, the dosage is small enough in monthly Heartworm pills that it is “okay” to give him.
    No offense, but I don’t want him to have ANY amount of a drug that has such risks for him! To me, it’s just not good enough to tell me that a drug can kill him, but a little bit is ok so give it to him.
    I want to protect him from Heartworms and I don’t believe most of the “natural” options out there. Someone just told me the other day, “Well, if your dog is healthy and getting all his vitamins, his body will be able to fight off Heartworms naturally!” Then proceeded to try to sell me supplements and vitamins for him. Ya right!
    But what are my options here?

  12. skeptvet says:

    Unfortunately, you have some misconceptions about the MDR1 mutation and its implications. Because the avermectins (such as ivermectin) can cross the blood/brain barrier in these dogs, it is possible for them to experience side effects at therapeutic doses that other dogs do not. However, the heartworm preventative doses are orders of magnitude lower than doses for treating parasites like demodectic mange, and thousands of these dogs receive these drugs all the time with no ill effects. The risk from not using a preventative would be so much greater in an endemic area than the risk from ivermectin, it would make no sense to avoid the drug.

    However, you are lucky in that MDR1 mutation status isn’t relevant for all of the drugs used to prevent heartworm, just for the avermectins. Milbemycin is actually used in these dogs at a therapeutic dose for demodectic mange, which is the monthly heartworm preventative dose given daily for many months, and again there are no ill effects in these dogs. So there is no reason at all to avoid monthly use of milbemycin even in MDR1 homozygous recessive dogs.

    I would take a look at the site from WSU devoted to this genetic mutation. There are many safe and effective heartworm preventatives you can use, and there are NO so-called “natural” preventatives that have been shown to work.

  13. Jeanie says:

    I’m curious what you think of this particular product. It seems to have several positive reviews.

  14. skeptvet says:

    As with all others, this is a product that has never been tested to determine if it is safe and effective, so using it is taking a huge risk, especially since safe and effective preventatives already exist.

  15. Frank Pirkle says:

    Our dog almost died last year from acute liver issues. The cause was never determined. All the symptoms presented as Liver Disease/CAD. Bilirubin, AST, AGT number were off the chart. She had ultrasounds, biopsy, etc. It was touch and go for a few weeks. Change of diet, various medicines including denamarin(milk thistle) and ceased all preventative medicines. Happy to report her liver number all returned to normal.

    Due to the sudden onset (her numbers were normal a few months before during her annual) and than the sudden reduction they ruled out the liver disease/cad. But never could give a reason for the liver issues.

    I am torn on what to do with the heartworm preventative. She had been on Sentinel year long her entire life. We live in the NY area. We have not given her any heartworm since her liver issues last September. I very scared to give her the heartworm medicine since we still never found the cause of her liver issues.

    Any suggestions or advice?

  16. skeptvet says:

    Well, of course I can’t give specific advice without actually being there as your veterinarian. I will say, however, that the timing doesn’t suggest any relationship to the Sentinel, there is no evidence that this product causes liver problems and, if you are in a heartworm endemic area, not being on heartworm preventative can be very dangerous. So there is not really a sound reason I can see to avoid the heartworm medication in this situation.

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  19. Solana says:

    I use HW Protect on my dogs after one of them had an allergic reaction to Resolution, which we had used on him for many years. HW Protect appears to be getting the job done; they continue to test negative for heart worm every six months.

  20. v.t. says:

    Solana, your dogs may be testing negative, only because they have not been infected. That does not mean it is due to the product you’re using. The majority of “holistic” products contain little to nothing effective, or substances which have never been tested for safety or efficacy. I can’t understand why owners choose blind belief over proven and effective strategies, particulary in serious and deadly diseases like heartworm.

  21. Diane says:

    V.t.–I can’t understand it, either. There seems to be a fundamental human psychological flaw that causes people to be terribly attracted to “alternative” products and (so-called) therapies, like moths to various flames. Maybe it’s an inner child thing, wishing for magic to be real. And for some reason people also seem inclined to dismiss information and ideas that they perceive to be mainstream. IMHO critical thinking should be taught in school, starting at an early age.

  22. Cheryl says:

    The drug companies make big $$$ of course this article is another example of this. Vets suggest vaccinations that aren’t necessary, etc. for what? More $$! Doctors prescribe medications like it’s going out of style, and dispute any claims of natural healing, or that supplements don’t work. WAKE UP PEOPLE!!! it’s all about $$$$.

  23. skeptvet says:

    Paranoid and ignorant. There is challenging bogus therapies, and the folks who sell fake therapies make money off of them just as vets who sell real medicine do. Hysterical accusations without any scientific evidence illustrate only the weakness of the claims you make.

  24. Jodi says:

    I am a member of a very large and active Yorkie dog forum and of course there are all types of personalities and opinions regarding everything Yorkie related. Recently, two different “natural” HW preventions were suggested. One being natural amber beads worn around the pets neck and the other a homeopathic pill called MosiQ that can be ingested by both humans and our pets to repel mosquitos. What are your opinion on both of the above suggested remedies which are being suggested along with mosquito control of fogging. One of the many argument for not using a HW prevention like Heartguard(just and example) is the tiny size of the breed compared to the weight on the box of the preventatives. I personally give HW prevention year round to all 3 of my small dogs without issue.

  25. skeptvet says:

    As I’ve discussed in great detail elsewhere, anything that is truly homeopathic in its makeup is, essentially, just water and has no biological effects beyond placebo whatsoever. Certainly, this is not something one should rely on to prevent a serious disease like heartworm.

    As for amber beads, I’m not aware of any specific research, but I find it difficult to think of a biologically plausible mechanism by which one could trust something like this to repel mosquitoes effective enough to prevent heartworm disease. I wouldn’t trust the life of my pet to something like this without a believable mechanism and good clinical evidence.

    The heartworm preventatives, on the other hand, have been extensively tested for both safety and effectiveness and used widely in literally millions of dogs. We know they work. We know he risks are extremely small and mostly associated with specific genetic markers (MDR1 gene) in particular breeds. While I understand the concern about dose in small dogs, the heartworm preventative doses are hundreds of times smaller than the therapeutic doses used for other diseases, such as demodectic mange. The monthly heartworm preventative dose of milbemycin, for example, is actually give DAILY to treat mange in dogs with an ivermectin sensitivity due to the MDR1 gene, and it causes no adverse effects at this dose. So while it is a reasonable concern, there is good evidence that these preventative medicines are safe at label doses. The risk of hearwtworm disease is certainly going to be much greater if you live in an area where it is endemic.

  26. Parker Anderson says:

    Hey Skep Vet, you’d have a field day with this “rescue”. Not only does the owner of Reunion Rescue believe in “natural” heart worm remedies, she also believes in “detoxing” dogs from over-vaccination, treating kennel cough with herbal medicine and thinks most (all?) vets are on the take from pet food companies.

  27. Laura says:

    I totally disagree with you Skept Vet. I believe that CURES come from natural sources. Drugs of any kind, whether it is for pets or people, are only “treatments”. Treatments meaning that it doesn’t CURE anything ans has the patient coming back for more. The internet can be a positive and negative place. Do your research people and find out what is going on before you listen to your doctors and vets.

  28. skeptvet says:

    “Do your research….before you listen to your doctors and vets.” You realize that what you are suggesting is that to look up stuff on the internet and believe total strangers without a medical education is safer than listening to your doctor? Sorry, but that is completely crazy.

  29. Jerseygirl says:

    I just wanted to thank you so much for this forum. I was trying to decide on natural or holistic heartworm preventive vs medical heartworm preventive, such as Heartgard. Yes, I got caught up momentarily with the natural/holistic approach, but am now convinced due to the arguments here that I am not going to take a chance on my girl’s life by using anything that hasn’t been proven to prevent heartworm disease. Thank you Skeptvet!

  30. VeggieNut says:

    I’ve never tried natural heartworm preventatives for my dogs. I live down south where mosquitoes are as plentiful as splinters in a fence post. Since I’ve never had a problem with the traditional methods of heartworm prevention, I just don’t know that it’d be worth taking the risk by changing what I know is working. However, I have gone off the beaten path with treating oral squamous cell carcinoma in my sixteen year old kitty, Mandi. Since I have experienced a degree of success with this, I won’t throw the baby out with the bath water either and say that all holistic/natural methods are snake oil. My kitty’s initial treatment began with Clindamycin and Prednisone from the vet. However, the results from this were very short lived requiring frequent re-treatment. As soon as the effects from the meds wore off, the ulceration, drooling, etc. all came back, BIG TIME. I felt like a yo-yo. After the last round of this protocol, the ulceration in her mouth was still there. Out of pure desperation, I looked for something else to try. After two weeks of the molasses/baking soda cancer cure, the ulceration was GONE!!!! Laugh if you will, but I’m a believer! That was three months ago and I’m still using holistic/natural treatment exclusively. Currently, the massive ulceration is GONE, the drooling is GONE, the pawing at her mouth is GONE, the not eating at all is GONE, & the lying on her sick bed all day is GONE! Best of all, since I started her on natural treatments, these symptoms have stayed GONE – no yo-yo syndrome! She is still thin & she still has some visible tumor way in the back of her mouth. However, since I can give her this holistic course of treatment daily, it has helped her to stabilize as there’s no “on/off” schedule and this has greatly helped to maintain her quality of life. I’ve also added Artemisinin (not given every day), Triple Mushroom Complex standardized consisting of Maitake, Shiitake, Reishi mushrooms, a multi-vitamin, Astaxanthin and some other supplements which vary. I’m still researching this to learn as much as I can in order to better help my Mandi. We’ve now passed the nine month mark since this cancer was found in her mouth, and I’ve still got my kitty! Considering her advanced age of 16 years and the poor prognosis of this type of cancer, I’d say using holistic medicine exclusively can sometimes be preferred over conventional medicine. However, sometimes combining the two may produce better results than either one used alone. It can be a hard, hard decision to know which way to go. For me, it was pure desperation and my only regret is that I didn’t know about it sooner.

  31. skeptvet says:

    I won’t throw the baby out with the bath water either and say that all holistic/natural methods are snake oil.

    Neither would I. Every therapy needs to be evaluated individually on its merits.

    That said, the idea that the treatment you are using is truly effective against squamous cell carcinoma can only be true if a great deal of well-established science is wrong. That is always possible, but it is far more likely that there is some other explanation for what you’ve seen. Misdiagnosis, spontaneous changes in disease, and many other factors can make ineffective therapies look like they work when they don’t. I know, of course, that you will never believe things aren’t as they seem to be, but believing in uncontrolled anecdotes like this rather than controlled studies supported thousands of years of clearly dangerous and ineffective therapies (e.g. bloodletting, ritual sacrifice, etc.) and continues to support every type of belief from UFPs and alien abduction to creationism. Either anecdotes are unreliable, or everything is true.

  32. VeggieNut says:

    The odds of misdiagnosis is pretty slim since two veterinarians have seen her. Unlike me, they did go to an accredited School of Veterinary Medicine. I think that the diagnosis of feline oral squamous cell carcinoma is more than very likely to be correct.
    Also, it is important to note that since conventional medicine just wasn’t working very well any more, I had nothing to lose by exploring different methods of treatment, proven or not. However, in my search for information, I found other pet owners with the same problem who got positive results from using holistic/natural treatment for oral squamous cell carcinoma. Some of these alternative methods I am using have been successfully used for centuries in other countries and are currently being used by holistic practitioners today. There are holistic Veterinarians with websites where they share their knowledge of what has worked in their practice. That does lend a bit more credibility to alternative medicine and it’s definitely above the level of blood letting, ritual sacrifice and uncontrolled anecdotes. Considering the advanced stage of this cancer, if I had decided to wait for alternative methods of treatment to be conclusively proven effective, me and the cat would both be dead of old age still waiting for the proof. I’ve found that if I want to succeed at anything, I have to take what I’ve got, where I’m at and do the best I can with it. That’s what I’ve done and I do believe that it has provided some beneficial results in my case.

  33. skeptvet says:

    The odds of misdiagnosis is pretty slim since two veterinarians have seen her. Unlike me, they did go to an accredited School of Veterinary Medicine. I think that the diagnosis of feline oral squamous cell carcinoma is more than very likely to be correct.

    Was there a biopsy to confirm the diagnosis and also to confirm the remission?

    I had nothing to lose by exploring different methods of treatment, proven or not. H

    This is a common misconception. People are hurt by unproven therapies all the time, and even with untreatable terminal diseases there have been studies showing people who choose unproven treatments can have shorter lives with greater discomfort. Unproven by definition means not only do we not know if it helps, we don’t know if it’s safe, so it pzzles me that people always assume it must be despite the evidence against this assumption.

    I found other pet owners with the same problem who got positive results from using holistic/natural treatment

    You found more anecdotes like your own. Unfortunately, no matter how many of these are collected, it doesn’t become a reliable guide to what works and what doesn’t. Every therapy ever invented, included those universally acknowledged to be unsafe and ineffective (such as the bloodletting and ritual sacrifice I mentioned before) have been able to produce many anecdotes showing they supposedly worked.

    of these alternative methods I am using have been successfully used for centuries in other countries and are currently being used by holistic practitioners today.

    The fact that people use them doesn’t show they work. People use astrologers and psychics and have for centuries. people practiced bloodletting and purging for centuries. These don’t work, so history of use doesn’t mean a treatment works.

    There are holistic Veterinarians with websites where they share their knowledge of what has worked in their practice. That does lend a bit more credibility to alternative medicine and it’s definitely above the level of blood letting, ritual sacrifice and uncontrolled anecdotes.

    That’s the point, it doesn’t. More anecdotes or opinions from people who believe in something because of their personal experience doesn’t add up to more reliable evidence. There is no difference between doctors who believe in homeopathy today and doctors who believed in bloodletting for two thousands years. They all make the mistake of relying on fallible personal experience over scientific evidence.

    Again, I realize that facts almost never change anyone’s mind once they’ve had what feels like a positive personal experience. I don’t expect you to change your mind. I am simply pointing out that your experience is exactly like that of millions of other people as smart and well-intentioned as you who believed in their treatments as strongly as you believe in your but who turned out to be wrong. As John Stuart MIll put it:

    While every one well knows himself to be fallible, few think it necessary to take any precautions against their own fallibility, or admit the supposition that any opinion, of which they feel very certain, may be one of the examples of the error to which they acknowledge themselves to be liable.

  34. Catherine says:

    If natural remedies work for humans why wouldn’t they work for our pets too? MoziQ by the way does work well as an oral insect repellant. Why wouldn’t it work for dogs?

  35. skeptvet says:

    If natural remedies work for humans why wouldn’t they work for our pets too?

    1. First you have to prove they work for humans. This has almost never been accomplished, the NCCAM has spent billions studying alternative therapies without much success at showing they work, so there is an unreliable assumption here.

    2. Tylenol “works” for humans and kills cats. Grapes and raisings are fine for people and can be poisonous for dogs. Humans and pets have significant biological differences and the diseases they develop, the causes of these diseases, and the preventative and therapeutic interventions that work for cats and dogs are going to be different than for people. There may well be plenty that work the same in both, but you can’t assume this, you have to show it with proper research.

  36. kareninca says:

    Dear Skeptvet,
    Our dog has very serious IBD (she is getting ongoing treatment at UC Davis for it), and every heartworm preventative we have used has caused her to have terrible flare-ups. The topical preventative was the worst! In order to give her plain ivermectin (which doesn’t have any of the food components that would also cause a flare-up), she has to be on prednisone for at least a week each month.

    We would be more than willing to have her have the heartworm test done every single month, without fail. Would that be a safe way to avoid having to give her this preventative? If she is tested each month, would that catch any infection within a safe time frame? We are afraid of her getting infected, but her colon is in very bad shape.

  37. skeptvet says:

    Sounds like a rough situation. My understanding is that the problem for dogs with food sensitivity is that flareups are triggered by food proteins. I have never seen a dog react to plain ivermectin (as opposed to flavored preventatives), and I can’t quite understand why that would happen, or why topical selamectin would be a problem. Have you asked the folks at UCD about that?

    If you have tried every form of unflavored HW preventative and none are tolerable, you are kind of stuck. Testing isn’t a great option because if she gets infected then you have to treat, and it’s hard to imagine how she would tolerate the treatment if she can’t tolerate the preventatives. The risk will vary based on where you live and also, in some locations, on the time of year. I would try to find out exactly what the transmission season and risk is in your as best you can, so you can limit the number of months when transmission is possible and prevention is needed. In my area, for example, there is essentially no local HW transmission because we lack the vector, so prevention might not be needed at all. There is also some safety net built in to the preventative dosing, so if, for example, you have a 4 month transmission period and the preventatives effectively block infection for 8 weeks, rather than only 4, you might get away with two doses a year.

    The best way to figure this out would be to talk with the parasitology folks at UCD about the risk/transmission season in your area and the minimum number of doses you could get away with to effectively eliminate most risk of infestation.

    Sorry I don’t have a magic bullet. Good luck!

  38. kareninca says:

    Thank you so much for your reply. We are so busy dealing with Sophie’s IBD with the people at Davis – she was just scoped, and her colon is a mess – that we haven’t brought up that particular cause of flare ups. Yes, proteins are generally the thing, and they are for her. But Ivermectin itself is also pretty clearly a problem.

    I just found out that the one form of heartworm preventative that we haven’t yet tried – Sentinel (milbemycin oxine) is available again (the factory was out of commission for 16 months). We will try that next month. It isn’t “pure” like the Ivermectin we have made up by the compounding pharmacy, but the tablet is small and she’ll be on prednisone anyway.

    It is so hard to get a straight answer re what months here in Silicon Valley are dangerous. One of our vets here doesn’t give his own dogs heartworm preventative at all. Another of our vets finds this shocking. Trying to go by what the typical temperature is outside, seems hazardous, when you see mosquitos around (as we do). On the other had, we gave her Ivermectin five days ago and she has had blood in her stool every since (before the Ivermectin dosage the blood was clearing up).

    Again, thank you. I had thought that the farthest one could go was six weeks; I will look into the possibility of eight weeks, and try to see if there are “safe” months.

  39. skeptvet says:

    I believe the risk on the SF Peninsula is extremely small, and I don’t necessarily recommend HW prevention either for dogs that never leave the area. There have been cases reported from Gilroy, Santa Cruz, Tahoe, Central Valley, etc., so there are areas of transmission around the Bay Area, but it seems very unlikely in your area, so if the milbemycin isn’t tolerable, you may be in the position of balancing a small but uncertain risk against a clear harm in terms of the IBD. Frustrating!

  40. kareninca says:

    Thank you so much for helping me balance this decision. We are very risk averse, obviously, and whenever we see a coyote (once a year!), I think, “ack, that’s a heartworm carrier!!!” Or someone’s flower pot basin full of water. But I have also just read that indoor dogs are one fifth as likely to be bitten as outdoor dogs (our dog is an indoor dog, except for brief walks), and female dogs one fifth as likely as male dogs. And we never take her out of the area. We will see how the milbemycin goes!!

  41. kareninca says:

    Just as an update, in case anyone else out there is having trouble with heartworm meds. We have found a clinical trial that supports using a very low dose of milbemycin to prevent heartworms:

    “Milbemycin oxime, the active ingredient in Interceptor, has been approved by the FDA at one-fifth the regular dosage to kill heartworms only, without controlling intestinal parasites, including roundworms, whipworms and hookworms. Novartis received FDA approval for a product, “Safeheart”, with this lowered dosage of milbemycin, but it appears that they don’t intend to market it. (You can read the FDA approvals showing that milbemycin oxime will control heartworm at one-fifth the dosage found in Interceptor on the FDA’s web site; see “Resources” below).
    The actual recommended dosage of milbemycin oxime for heartworm prevention only is 0.05 mg per pound of body weight (0.1 mg per kg). Contrast this with the recommended dosage of Interceptor for control of heartworm and intestinal parasites: 0.23 mg milbemycin oxime per pound (0.5 mg/kg) of body weight. Heartworm can be prevented at a much lower dose than that needed to control intestinal parasites.”

    Please note that the author of the “dogaware” article no longer endorses this approach, because of the emergence of resistant strains of heartworm (a horrifying subject in itself)( Her reasoning is that you’d better use the full dose, just in case. I don’t think this makes sense: either a particular heartworm parasite is susceptible to a particular med, in which case the low dose used in this study should work, or it isn’t susceptible, in which case it wouldn’t matter if you gave a higher dose. (I know that ever-higher doses are used to overcome resistance in other meds e.g. TB, but that is a poor stop-gap).

    So far low-dose milbemycin (in Sentinel form) has not caused our dog to have blood in her stool. Because she has severe colon damage from an unknown cause (she has gastric IBD, but no signs of colon IBD other than the actual damage), this is very important to us (we fear that the Ivermectin may have been an ongoing cause).

  42. Audrey says:

    what are your thoughts on Trifexis?

  43. skeptvet says:

    The data in support of efficacy come from FDA labelling studies. These are pretty good quality, but they are conducted by the company producing the product (with extensive regulatory oversight), so there is some potential for bias. However, that is true for the overwhelming majority of the medicines we use, and independent replication of these studies isn’t a realistic proposition. I use the product for one of my own dogs and recommend it to clients, and I have seen no reason to doubt its safety or efficacy. I will say, though, that a lot of dogs appear to hate the taste. 🙂

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  45. Shawna says:

    I wonder if they plan to do more research with alcohols of ginger. This could give vets an alternative for those insisting on it if continued research shows the same benefit as this research.


    Dogs, naturally infected with Dirofilaria immitis, were treated with the residues of the alcoholic extracts of the rhizomes of Zingiber officinale (ginger). Twelve subcutaneous injections of the extract given at 100 mg/kg reduced microfilarial concentration in blood by a maximum of 98%. Fifty five days after the last injection there was 83% reduction in microfilarial concentration suggesting partial destruction of adult worms. Half of the treated dogs showed some lethargy at the beginning of treatment possibly due to the mass annihilation of microfilariae in blood.”

  46. skeptvet says:

    An intriguing study, but I do have to wonder why, if this is a useful approach, nothing else has appeared on it since 1987. Also, as the study noted there were some side effects, and the biggest risks for treatment of heartworm disease come from the dying off of the worms, not toxicity from the treatment medications. Any effective product that kills worms will have the same risks, so it’s not clear this would be better in any way than the current effective treatments.

  47. Brady says:

    Hello, thank you for this helpful article. I am shocked by the articles you posted and read them one by one. While most of them are written by laypeople, in particular the 10th article caught my attention. The person posted claims to be a Dr. to be precise a a veterinarian. How can one verify if this person is a real vet and other people claiming to be vets in general? I see his articles posted in many places, and I then stumbled on this post where he was giving ill advice to purchase human vitamin K for a dog with rodenticide poisoning and claiming that it is the same thing as the veterinary version! Then saw another person (not a vet!) posting oodles of proof that they are not the same thing. Here is the post in question:
    Now, wouldn’t a real vet know that vitamin K for humans is different? Could this vet be a crook? How can one determine the real credentials of somebody? Isn’t giving veterinary advice online lie this in breach of practicing veterinary medicine? I feel very vulnerable when I see posts like this as I feel it’s a form of fraud.

  48. skeptvet says:

    Every state licenses vets separately, so you can confirm if a veterinarian is currently licensed by checking the database for the state in which they are licensed. However, some vets who sell products or give advice on the internet don’t see regular patients and so don’t maintain an active license. And plenty of licensed vets belief nonsense and give bad medical advice, so it often doesn’t matter if they are licensed or not.

  49. v.t. says:


    The “vet” in question claims on one or more sites that he used to practice in the US (midwest), although now lives in Brazil. I’m guessing he is no longer in practice and possibly does not maintain his US license.

    Many of his hubpages articles seem wishy-washy, in other words, he’s ok with telling pet-owners to do one thing but claims many things also do not have evidence of efficacy. That’s akin to giving advice to someone but also telling them “it’s ok to try this but don’t blame me when it doesn’t work or causes harm”. He has some articles that seem to sway on the side of alternative (raw/paleo nutrition, heartworm preventatives, home remedies, blah blah blah), again, in that same wishy-washy fashion.

    His website does not provide any means to determine his real name or credentials, so, beware of websites that do not provide such information.

  50. Ann Weber says:

    I had a dog who had hallucinations and became depressed after taking heartguard. She eventually contracted canine carcinoma that killed her. I worried about giving heartworm meds to my next dog. A wholistic (fully certified) vet told me that giving her Sentinal 4 times a year was all I needed to do to prevent heartworms. She is now 4. Do you agree with his advice?

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