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  • #139164 Report Abuse
    Patricia A

    canineCanine heartworm disease is transmitted by infected mosquitoes.

    In the worst case scenario, it results in a fatal worm infestation in the heart and blood vessels of an infected dog.

    Fortunately, heartworm disease can be prevented. It can also be successfully treated when caught in time.

    The American Heartworm Society (AHS), an organization that studies the disease, its treatment and prevention, recommends yearly heartworm testing for all dogs. The AHS also recommends year-round chemical preventives for every dog over the age of eight weeks, regardless of where the dog lives.

    Dr. Becker’s Comments:
    The American Heartworm Society has three “platinum” sponsors and five “bronze” sponsors. All eight are major pharmaceutical manufacturers.

    It comes as no surprise, then, that the AHS recommends year-round, birth-to-death heartworm prevention drugs – no matter where you live, the time of year, the age of your dog, his size or health status.

    What’s Wrong with This Picture?
    Three things, specifically:

    Huge conflict of interest potential. Heartworm prevention through the overuse of potentially toxic medications sold by pharmaceutical giants like Bayer Healthcare, Merial and Pfizer, is a virtual money machine for drug manufacturers, online retailers, testing laboratories, veterinarians and any other entity that can find a way to cash in.

    When there’s money on the table – in this case billions of dollars – your pet’s health and quality of life can quickly become a secondary concern.

    Note also that the ASH recommendation for year-round dosing is not because your pet needs it year-round in every state, but because it’s assumed dog owners will forget to re-start the medication when the weather warms up.

    And by the way – heartworm “preventives” don’t actually prevent your pet from getting worms. What they do is poison the larvae at the microfilaria (L1-L2) stage of development, causing them to die.

    Relatively low actual incidence of life-threatening infection. Heartworm disease is more difficult to acquire – and less lethal – than the dire warnings and marketing claims for chemical preventives would have you believe.

    In order for heartworm disease to take hold, a precise sequence of events must occur involving the right climate, the right temperature for the right amount of time, the right species and sex of mosquito, and your dog’s less-than-optimal immune system function.

    This information is not intended to minimize the need to protect your dog, but only to point out the actual potential for heartworm disease is less than you’ve been led to believe by financially-motivated marketing campaigns designed to scare pet owners into buying 12 doses of preventive, year in and year out, regardless of where you live!

    The existence of less toxic recommendations. There are less harmful protocols to prevent heartworm in your dog than a lifetime of once-monthly, year-round doses of toxic drugs.
    How Heartworm Disease Happens
    Heartworms are a variety of roundworm with the clinical name dirofilaria immitis. They are spread by mosquitoes.

    Dogs can only get heartworm disease through infected mosquitoes. They can’t get it from other dogs or other types of animals, from dog feces, or from their mothers while in the womb or through nursing.

    Only certain mosquitoes can transmit heartworm to your dog. These mosquitoes must meet certain precise criteria, including:

    They must be female.
    They must be of a species that allows development of the worms in the cells of the body (not all species do).
    They must be of a species that feeds on mammals (not all do).
    They must have bitten an animal infected with stage 1 (L1) heartworms about two weeks prior, since approximately 14 days are necessary for the larvae from the other animal to develop to stage 3 (L3) inside the transmitting mosquito.
    This mosquito must then bite your dog. When the larvae reach stage L4-L5, which takes three to four months, under
    the right conditions they can travel via your dog’s bloodstream to the lungs and heart.

    If your dog’s immune system doesn’t destroy these invaders, they will reach maturity (L6), the adult stage, in which males can grow to six inches in length and females to 12.

    Two other critically important features in the transmission of heartworm are:

    The right temperature. During the time the heartworm larvae are developing from L1 to L3 inside an infected mosquito, which is approximately a two-week period, the temperature must not dip below 57°F at any point in time. If it does, the maturation cycle is halted. According to Washington State University heartworm report from 2006, full development of the larvae requires “the equivalent of a steady 24-hour daily temperature in excess of 64°F (18°C) for approximately one month.”
    Humidity and standing water. Mosquitoes are a rarity in dry climates.
    As you can see, in order for your dog to develop heartworm disease, a number of things have to happen with near-perfect timing under a precise set of circumstances.

    Information on how many cases of canine heartworm disease occur each year in the U.S. is scarce. The AHS provides a heartworm incidence map for the years 2001, 2004 and 2007 which you might find helpful. Keep in mind it is a very general guideline and shouldn’t be viewed as the only decision-making tool at your disposal.

    Assessing Your Dog’s Risk
    There are only a few areas in the U.S. in which giving a nine month to year-round heartworm preventive might be advisable – those areas are in south Texas, south Florida, and a few other locations along the Gulf coast. The rest of the U.S. ranges from three to seven months of high exposure risk. The majority of states are at six months or less.

    Given that heartworm preventives are insecticides designed to kill heartworm larvae inside your animal, and therefore have the potential for short and long-term side effects damaging to your pet’s health, the first bit of information you need is your dog’s actual risk of exposure to infected mosquitoes.

    • This topic was modified 4 years, 10 months ago by Patricia A.
    #139176 Report Abuse
    Patricia A

    Ooops..Forgot to write after I copied and pasted my questions. Which if any heart worm medication do you use. Has anyone experienced side effects with any of the medications? Never gave all year since I live in the North East so have cold weather starting in the fall. Have an appointment with my vet for blood work. I want to get a heart med that ONLY kills the heart worm larva if my dog gets infected and NOT the all in one flea/tick and other parasites which I gave last year.
    I just hate giving my two small dogs these poisons but I don’t want to take the chance .

    #139195 Report Abuse

    My roommates dog has been on bravecto and incepetor his whole life. Every month and three months. No issues. Every dog is different tho. So if you’re worried give half the chew one day then the rest the next day so they aren’t getting such a huge dose immediately .

    #139206 Report Abuse

    Quote “So if you’re worried give half the chew one day then the rest the next day so they aren’t getting such a huge dose immediately” .

    The full dose needs to be given at the same time for the drug to be effective. The combined ingredients work together and the drug is out of the dog’s system within 24 hours. They kill the mosquito larvae that may have developed the month prior, not the month ahead.


    “When splitting oral heartworm medication (especially soft chews), it is possible that you will not divide it evenly thereby resulting in one dog getting a smaller or larger dose. Additionally, oral heartworm medications have the active ingredients blended throughout and while theoretically the active ingredients are evenly distributed, there is no guarantee that there will be an equal concentration of the medication in each part. So, even if you’re able to split the chew exactly, one half could still have a higher or lower concentration of the active ingredients”

    #139214 Report Abuse

    Also, heartworm disease is difficult to treat, expensive and is very rough on the dog (diarrhea, lethargy).

    There are no guarantees the treatment will be successful. Therefore prevention via heartworm pills makes sense.

    #139215 Report Abuse

    Bravecto doesn’t work that way. It treats for three months out. It wouldn’t make any sense if it just treated for 24 hrs lol. And I would imagine heart worm is in the system longer than 24 hrs, seeing as how giving a heart worm preventative to an already infected dog can be deadly I doubt it has no long term preventative nature to it as this article states. But I was more referring to bravecto. As it has more medication in it and is in the system much longer.

    #139218 Report Abuse

    https://us.bravecto.com/pdfs/Bravecto-Chew-PI_9.11.pdf (excerpt below)

    Dosage and Administration: Bravecto should be administered orally as a single dose every 12 weeks according to the Dosage Schedule below to provide a minimum dose of 11.4 mg/lb (25 mg/kg) body weight. Bravecto may be administered every 8 weeks in case of potential exposure to Amblyomma americanum ticks (see Effectiveness). Bravecto should be administered with food.

    #139219 Report Abuse


    excerpts below (out of context)

    The heartworm life cycle is complex. The dog is infected by early stage larvae that are transmitted by a mosquito carrying infected blood. This larvae goes through multiple stages of development within body tissue before migrating to the heart and lungs as an adult heartworm.

    These adults produce microfilariae, the earliest life stage that circulates within the dog’s blood. Prevention kills only early stage larvae and microfilariae. This is why it is important to give your dog heartworm prevention every month. It kills the larvae before they develop into a stage that is immune to the medication in heartworm prevention.

    Most heartworm medications require monthly administration, while others work longer (up to six months with an injectible product called moxidectin or Proheart®). There are many choices of heartworm prevention available, from topical products to chewable oral medications; many come in both dog and cat versions.

    Monthly heartworm preventative medications do not stay in your dog’s bloodstream for 30 days. The active ingredients work to kill any larvae that have been in the system for the past 30 days, clearing the body each month. The medication is only needed once a month because it takes longer than a month for the larvae to develop to a stage where they reach the body tissues.

    Heartworm medications available today work to kill off the larval heartworms that made it into the dog’s body during the past month. The heartworms in dogs will die at certain stages of development, before they can become adult heartworms. However, heartworm preventives will not kill adult heartworms that are already present.

    #139220 Report Abuse

    Breaking it up into two doses in 18-20 hrs isn’t going to make a difference for a three month preventative. Sorry not gonna argue about this lol

    #139221 Report Abuse

    Well the thing that makes the most sense is for the OP to check with her vet.
    I hope that the OP returns to confirm what I have advised is true.

    ” Dosage and Administration: Bravecto should be administered orally as a single dose every 12 weeks according to the Dosage Schedule below to provide a minimum dose of 11.4 mg/lb (25 mg/kg) body weight. Bravecto may be administered every 8 weeks in case of potential exposure to Amblyomma americanum ticks (see Effectiveness). Bravecto should be administered with food”.

    It’s clear to me and to all other healthcare professionals what this means
    ” Bravecto should be administered orally as a single dose”

    #139222 Report Abuse

    If it’s your first time using a preventative that you don’t know how will effect your dog I see nothing wrong with splitting the dose the first time just to be sure. Seeing as how these meds have been reported to cause massive seizures and even death within 24 hrs of administering. It’s rare but it’s all fine and dandy until it’s you and your dog. I stand by what I said. Bye now. 🙂

    #139223 Report Abuse

    The ingredients are not evenly distributed within the pill/chew therefore you could cause a reaction rather than prevent one.
    If a nurse administered a medication in the manner you suggest, she would be written up for a medication error.

    “When splitting oral heartworm medication (especially soft chews), it is possible that you will not divide it evenly thereby resulting in one dog getting a smaller or larger dose. Additionally, oral heartworm medications have the active ingredients blended throughout and while theoretically the active ingredients are evenly distributed, there is no guarantee that there will be an equal concentration of the medication in each part. So, even if you’re able to split the chew exactly, one half could still have a higher or lower concentration of the active ingredients”

    #139225 Report Abuse
    Patricia A

    Going to speak to my vet about this alternative. Might not be too costly since I don’t have mosquitos year round.
    DNA Heartworm Testing: An Alternative
    Before giving your dog any kind of heartworm drugs, you can do DNA testing to see if there are any microfilariae in his system. This testing is different from the regular test your vet will do to find adult heartworms. It’s based on PCR (polymerase chain reaction) technology and it’s not only very accurate, it also tests for heartworm larvae (the regular test only tests for adult heartworms). This means you can find (and then treat) any larvae before they become a real problem!

    Heartworm DNA testing is available from HealthGene, a company that offers all kinds of DNA testing. Simply tell your vet to send your dog’s blood sample to HealthGene and the company will send back the results. Find them online here. If your dog tests positive, there are several natural, holistic options to treat the heartworm. If he tests negative, you’re good.

    [Related] 5 Natural Heartworm Treatment Alternatives. Find them here.

    How often do you need to test? Remember how I told you to keep that important number in mind? Here’s why it matters. Since it takes at least 5 ½ months for larvae to grow into adult heartworms, testing every 4 months will allow you to find those larvae before that happens and get rid of them. This means those adult heartworms, the ones that cause the problems, will never have a chance to fully develop. And testing every 4 months is only necessary in those areas where heartworms are a problem more than 8 months of the year. In those areas where the season lasts only 4 months, you really only need to test once a year, at the end of the season.

    #139227 Report Abuse

    Sounds like a scam!
    Good luck

    PS: Your information about mosquitoes/transmission is incorrect.
    PLEASE discuss with a veterinary healthcare professional (not the internet) before proceeding.

    #139231 Report Abuse

    Hope this helps http://skeptvet.com/Blog/2013/06/there-is-no-natural-or-holistic-heartworm-prevention-or-treatment-proven-to-be-safe-and-effective/ excerpt below, click on link for full article and comments

    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 mercola.com 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.

    #139234 Report Abuse

    ******** says:
    December 7, 2017 at 3:02 pm
    I agree that most natural/holistic remedies are snake oil.
    But… what do you think of testing the dog every 4 months for heart worms, and administering the medicine only after a positive (which presumably would be early enough that the dog could take the standard medication to eradicate the early-stage worms)?

    skeptvet says:
    December 7, 2017 at 8:25 pm
    Heartworm prevention has to be tailored to the local risk. In my locale, incidence is close to zero, so prevention is optional. In other places I’ve lived, risk is high year-round and I recommend year-round prophylaxis. The testing strategy you suggest wouldn’t work because the test identifies adult female worms, so it is not positive until there is already a patent infection. The preventative kills larval stage heartworms, so at that point it would be useless, and the adulticide treatment is much riskier than prevention.

    link to these comments is in my prior post

    #139235 Report Abuse
    Patricia A

    anon what exactly is incorrect in the article regarding transmission?

    A few days ago, one of my friends living in Vermont called me. She was wondering what I thought about heartworm prevention. She asked me to help her determine if the monthly administration of heartworm preventive medication is really necessary. The question threw me back to the 90s when heartworm prevention drug manufacturers decided to take North America by storm. I remember the drug reps visiting vet clinics on a regular basis telling us that it was only a matter of time and heartworm would be widespread in Canada. These visits were also accompanied by a subtle suggestion that selling heartworm tests and preventive drugs could be a significant source of income for the practice.
    As time progressed, the heartworm doom and gloom scenario didn’t happen and the risk of heartworm infection in my area was clearly exaggerated.

    On the basis of my findings, I made the decision not to recommend heartworm preventive drugs in the area of my practice because the risk was practically zero and administering any drugs is never optimal. In reality, no one can be absolutely certain if preventive medication doesn’t increase the tendency to chronic disease, organ failure or even cancer down the road.

    On the other hand, my friend’s situation is quite different because she lives in the eastern U.S., where heartworm is a real possibility. I saw her question as a great opportunity for me to review the lifecycle of heartworm once again to see if drug companies were honest about their recommendations for monthly prevention. To me, the monthly administration seemed to be kind of peculiar because, as far as I know, parasites do not carry an iPhone with a calendar and schedule.

    I decided to bring clarity to the current situation to see what frequency is needed for heartworm preventive drugs and also tell you more about the heartworm prevention alternatives that I use with my dog Skai. In order to do so, I need to give you answers to the following questions:

    What is the risk of heartworm disease in your area?

    What is the minimal frequency of administering preventive drugs?

    Are there any alternatives?


    The life cycle of heartworm is dependent on a temperature that remains above 57F (14C) for at least 45 days straight and at least two weeks of temperatures over 80F (26C). If these conditions are not fulfilled, the parasite cycle cannot be completed and your dog is safe.

    Based on the recommendations of Dr. David Knight and Dr. James Lok from the American Heartworm society, even with the most cautious conventional medical protocols, a year-round heartworm preventive schedule is exaggerated with the exception of Florida, some parts of Texas and Hawaii. According to their conventional opinion, preventive treatment is unnecessary in the winter months and definitely doesn’t need to be started before or after the months noted on the map in their paper.


    Before you succumb to the marketing pressure and fear and administer heartworm medicine monthly, I urge you to learn more about the heartworm life cycle. Heartworm development goes through several stages before reaching maturity and it takes two-and-a-half to four months before the tiny stage of microfilaria leaves the muscles and starts settling in the pulmonary artery. When heartworm reaches its final destination in the pulmonary artery near the heart, it takes about three to four months to reach maturity.

    One doesn’t need to have a degree in math to figure that it takes somewhere between five-and-a-half to eight months for microfilaria to mature into an adult worm and that your dog should be safe if you administer heartworm meds only once every three to four months if you live in an area where heartworm occurs.

    So why would the drug companies recommend monthly heartworm prevention? The reason is clearly identified in Drs. Knight and Lok’s study:

    “…given what is presently known, continued adherence to a policy of superfluous chemoprophylaxis is disquieting because financial expediency for the veterinarian conflicts with clinical objectivity and client consent is predicated on unrealistic expectations. Clients mistakenly believe that they are purchasing additional protection for their pets, but in reality they are not. If the truth was known to them, few clients would agree to unnecessarily double their expense for heartworm prevention.”

    In real language, most vets are too busy to question the recommendations that drug companies give them about heartworm prevention. I strongly believe that the main reason for over recommending heartworm prevention (chemoprophylaxis) dose frequency is that drug companies can double or triple their revenues.

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    My dog Skai and I travel to Hawaii approximately twice a year for two months and I had to face the dilemma of what to do about heartworm. I never felt totally comfortable about giving him any drugs because, in my mind, there is no such thing as a little bit of poison.

    Luckily, advances in heartworm testing brought about DNA testing on the basis of PCR technology, which allows me to test three times a year for any presence of heartworm. This test has virtually no false negatives, which is great news for your dog.

    I can see that these tests are a serious threat to the hefty profits of heartworm meds manufacturers because they are simply not needed if you follow this formula. The duration of the heartworm season can be found on the map on page 79 of the study.

    Season Duration Number of Tests Required
    (The last should be done at the end of the heartworm season)
    Less than four months 1 test
    Four – eight months 2 tests
    Eight – 12 months 3 tests
    Considering the facts above, in order to prevent heartworm and keep your dog safe, all you need to do is test your dog if you live in an affected area. If the results are positive (heartworm DNA is present) make sure that you consult your veterinarian before administering any heartworm meds. Heartworm preventive medication can be used only if adult heartworms are NOT present because using preventive drugs on adult heartworm can cause serious problems and a different treatment protocol must be used.


    I regret to say that similar to the vaccination scam, monthly heartworm prevention is yet another dishonest marketing plot. What I am confused about is why drug companies continuously try to trick us and frighten us, instead of making a living the honest way. No matter what they are planning to try next, I believe that eventually, they will have to become more honest in order to survive because it is much more difficult to hide the truth in the age of worldwide web.

    Wishing you a happy, more informed heartworm season.

    © Dr. Peter Dobias, DVM

    Did you enjoy this article?

    #139237 Report Abuse

    This is getting repetitive. My last post on this thread.

    Again, speak to a veterinary healthcare professional that has actually examined your dog and knows it’s history.

    PS: I no longer read anything from homeopathic vets, I consider them to be dangerous.
    Find out the hard way. Many of us have.

    #139241 Report Abuse

    It’s not just about the location, more and more heartworm infected dogs are being transported from down south to shelters here in the Northeast.
    My friend adopted a lab mix that came from down south he tested negative for heartworm prior to transport, 3 months later he tested positive (it doesn’t show up right away) and my friend spent at least $1000 and had to deal with a sick dog for over a month.
    If a mosquito bites an infected dog and then bites your dog…..
    You get the picture?

    Heartworm disease is more prevalent in dogs now. That’s a fact.

    #139242 Report Abuse

    I agree! And, I used to look at them. But, thankfully, now I know better!

    Seven Dog Pages You Need To Stop Linking To:

    #139243 Report Abuse

    Veterinarians in Colorado should no longer base heartworm testing and prevention recommendations on only historic heartworm risks and prevalence. Heartworm prevalence in Colorado rose 67.5% from 2013–2017. Veterinarians and pet owners in areas with historically low heartworm prevalence should reevaluate the increasing risks posed by heartworms and should follow the testing and prevention guidelines provided by organizations like the American Heartworm Society and the Companion Animal Parasite Council [26, 30]. While animal shelters and other animal welfare organizations provide important rescue and relocation services, relocated dogs may be introducing higher risks of parasitic diseases. Repeated heartworm testing and movement restrictions should be considered for dogs originating from states with a high prevalence of D. immitis in order to reduce the spread of parasitic diseases. Imported dogs initially testing negative for the presence of adult heartworms should be re-tested six months later as antigen tests are not reliable at detecting immature infections. Further research regarding the heartworm status of imported dogs could help confirm the association of increasing heartworm prevalence and dog importation.

    https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-019-3473-0#Comments excerpt above

    #139244 Report Abuse

    PETA may be extreme but I don’t include them in with the homeopathic crowd.

    Some of their information is helpful and they do a lot to help animals.

    #139383 Report Abuse

    Wow! Here are my thoughts regarding Peter Dobias’s recommendations…

    Heartworm DNA testing. Dobias wrote “This test has virtually no false negatives, which is great news for your dog.”

    PCR tests in general are very sensitive and so that statement may be technically true. But the manner in which he is applying the test I think false negatives will be the norm. The test is based on DNA which is in a cell’s nucleus. Heartworm larva migrate in the sub Q tissue. How is it that larva cells can get from the sub Q into the circulatory system? They are too big to cross vessel walls. The larva do leave the sub Q and enter the circulatory system and at that point I’d expect they can be detected. However the dog is now infected with young adult heartworms. The time frame to prevent infection has passed.

    Preventatives are effective against young larva, the older the migrating larva are the less effective the kill rate. Even if this test can pickup migrating larva, by only testing every 4months, the infection cold be four months old and difficult to arrest at that point.

    His temp data doesn’t look accurate. Heartworm development in the mosquito progresses with warmer temps. Units referred to as heartworm development units. need to accumulate. Sustained high temps are not required.

    The reason for extending prevention beyond exposure dates is that it is documented that one dose of preventatives doesn’t always prevent infection. In one study one does didn’t prevent infection and three doses a month apart from each other did.

    In my opinion the alternative program as outlined by Peter Dobias is reckless at best.

    #157093 Report Abuse
    Jason H

    There many side effects of different medications on different persons but I know some common side effects that are:

    1- Constipation.
    2- Skin rash or dermatitis.
    3- Diarrhea.
    4- Dizziness.
    5- Drowsiness.
    6- Dry mouth.
    7- Headache.
    8- Insomnia.

    By the way, I owned one of the best pest control companies in New York City, Queens, and Nassau County since 1970. For more information about any of this type of staff, you may visit :

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