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What options do I have in heartworm “prevention?”

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  1. Ian

    I specifically would APPRECIATE lists of companies or names ….and want to know who your favorites are…. so I don’t have to do the research 🙂 I have been giving my dogs monthly batches of Trifexis but noticed my older dog’s hind legs shaking and of course read online that some people were concerned this was a side effect of the spinosad. Of my two dogs she particularly has recently been throwing up the Trifexis (and then re-eating it) which seems like a clear signal that it is toxic to her. At a recent vet visit to inspect a lump on her hind leg I questioned him about his experience with Trifexis and he said 1) her hind leg weakness was likely the result of something else like a spinal issue 2) he did think that we overmedicate our dogs for fleas and parasites and he doesn’t think they really need monthly dosage year round. He said something about a Sentinel product he liked but I didn’t write it down. My dogs are mostly indoors but do have limited but occasionally contacts with fleas from feral cats and rats outside and some mosquito exposure when they are on the front porch or on walks.

    1. Cathy Alinovi

      Try Interceptor.

    2. Peter Anderson

      Spinosad is a neurotoxin. I use it to kill leafminer worms in tomato plants.
      It has the ability to penetrate the surface of the leaf.
      Wouldn’t dare to use it on my 3 big dogs.
      Do a search on Spinosad. It is sold in garden stores.
      I use IverhartMAX (ivermectin/pyrantel pamoate/praziquantal)-Kills all the worms -not the dogs.
      Use it once a month during the summer months and every other month otherwise.
      My vets say my dogs need it only once every 3 months but I live in South Louisiana-don’t want to take a chance.

      1. Gman

        Interesting. You use a known poison on your tomatoes (that you then eat, I assume), but “wouldn’t dare” to use it on your dogs.

    3. Karen Mitchell

      More than likely you are over doing it. You don’t need to use all those chemicals. Think about it, you give your pets these chemicals, then, you over-vaccinate, you probably give them tap water to drink, which has been treated, more than likely you use pesticides and chemical fertilisers, as well as these flea and worm treating chemicals. THEN, there’s the food you feed. If you’re not feeding a PMR or BARF diet (Prey Model or the Biologically Appropriate Raw Food Diet), then you’re feeding them toxins on top of toxins. Then you have things like cigarette smoke, environmental changes, anxiety and stress.

      So what does all this have to do with your pet? A LOT!
      You don’t say how old your pets are. I would certainly look into their immune system because with any toxins they compromise the immune, therefore heath problems persists.

      If your seeing a conventional vet, try seeing a holistic or homeopathy one instead and learn ways to keep their immune healthy.
      If you need help with this and your in Facebook, look up my group named As Nature Intended. If you have problems with finding it, feel free to message me in FB.

      1. Ian

        Hi Karen, thanks for your reply. My older dog with the sometimes shaky hind leg is a 12 year old Shiba Inu. I agree I think the level of Trifexis was overdoing it (beyond just the simple issue of Trifexis or no Trifexis). She is just over the weight divider between two dose levels and of course they tell you then you need to use the larger dose. However I think if I continue with that product at all I will switch her to the lower dose range. I am not on Facebook but will use a friend’s account to check out your group.

    4. john space

      as my Charlie (a parsons Russell) is getting older, 15, his hind legs started shaking. he was in the beginning of kidney failure. that can also show up as a weakness in the hind quarters. I changed his diet to a home cooked diet after going to a holistic vet for info on a diet and put him on GNC SUPERFOOD VITAMINS as well as starting him on AZODYL. he appears comfortable and some of his numbers have come way down. were still fighting his BUN reading but I think were holding off the inevitable very well. his comfort and happiness are important above all else.

  2. Sherrie Ashenbremer

    I use Sentinel

    1. Ian

      I imagine Sentinel has different products, I guess I need occasional flea prevention with heart worm treatment probably 8 months of the year…. do you recommend a specific Sentinel product line?

      1. Lori S.

        Sentinel has two products, Sentinel and Sentinel Spectrum. They both kill heart worms. The Spectrum kills more other worms that the regular formulation does. The flea control is kind of mixed. It is the old Program, which you may or may not be old enough to remember – it stops flea eggs from developing past the egg stage, but does not kill adult fleas. So if your dog gets an infestation of adult fleas, then Sentinel may not be all you want; you might want something additional to knock down the adult fleas Three other things. One is that Sentinel is a chewable, and in my limited experience, dogs with digestive problems have more reactions to chewables than to topicals (while dogs with skin problems have the reverse). But that is just my anecdotal evidence, not actual evidence. Second, it does not have Ivermectin, so it is considered safer for Collies, Border Collies, Aussies, etc., but always check with your vet if you have one of these dogs or a mix of this. Third, the label says you must use it for 6 months after any exposure to mosquitos, so you cannot go on and off it, it is basically year-round.

        1. Sarah

          Most heartworm preventative are not terribly safe for collies or aussies. Ivermectin is not alone. I know. I have a mdr1 positive dog (not just a Gen carrier).

  3. Sherrie Ashenbremer

    We also live on a lake and we have a big wet lands in our backyard. Which is protected so we can not touch the wet lands. We can’t even sit outside in the summer past dark, the mosquitos carry us away. SO I use Sentinel because I feel it will keep my dogs heart worm free.

  4. Renee

    I just bought Serestor — not inexpensive. New to me and my golden.

  5. Bill

    I use several botanicals for over a decade on hundreds of dogs & cats with no side effects and complete effectiveness … can help with message

    1. Mimi

      How do I message you?

    2. Ellen

      How cn I message you about natural control of heartworm

  6. Karen S.

    It is my understanding that due to overuse of ivermectin (monthly) heartworm usage, mosquitoes are becoming resistant and even dogs on monthly “prevention” are getting heartworm. It is a classic overuse scenario. Has anyone found this in their research?

    1. Sherrie Ashenbremer

      I have not heard of this, that is really scary

  7. Jane Eagle

    Trifexis has killed dogs; I would not use it. Ivermectin is available at feed stores for livestock; I have been using it for years. Although a bottle may last your lifetime, it DOES expire, and I wouldn’t trust it too far past expiration. Also, I think the dose is not that sensitive; dogs who have mange are treated with massive doses of ivermectin. And it bears repeating:

    1. Carol D.

      If you want to be sure if your dog can safely receive Ivermectin, there is a genetic test available to tell you if your dog has the mutant gene that makes them sensitive to it. I know Washington State University sells the kits, its very simple and not terribly sensitive (last time I hear it was like $60) and then you can be confident in what you do. The gene mutation affects other drugs too, such as anesthetics.

  8. Kathrynne Holden

    You state: “One other very strong warning: do not give ivermectin to Collie breeds. Collie dogs cannot process ivermectin.” We have a Border Collie mix, and have been giving Heartguard. Is the warning applicable to Border Collies as well as the big collies?

    1. Cathy Alinovi

      Just Collies

      1. Kathrynne Holden

        Thank you so much, that’s a huge relief!

      2. Debbie

        on the ivermectin….Actually it is working breeds like GSD, Cattle dogs etc. google the MDR1 gene and you will see breeds listed. They offer that info on the Washington state university website also.

      3. Dr. Laurie Coger

        And Australian Shepherds, Mini American Shepherds, Shelties, and others. A complete list of breeds carrying the gene mutation (MDR1) can be found at Wahington State’s Diagnostic Lab website. You can also test your dog for the gene.

  9. Megan

    I use Amber Technologies VibactraPlus. Amazing stuff.

  10. Marge

    I buy from Pet Shed based out of Canada…prices are far less than the U.S. I have used Revolution for several years. Takes care of fleas, heartworm, worms and ear mites.


  11. Darlena

    I have over 15 years in pharmaceuticals and cannot figure out why some people buy into giving their animals what are essentially “killer” drugs. STOP, do not give your dog anything! The industry WANTS YOU TO BELIEVE YOUR DOG NEEDS CHEMICALS to survive. THEY DO NOT. There are a plethora of holistic remedies that help with fleas, etc… diatamacieous earth, citrus, clove, garlic, etc.

    Having been in the industry, I basically killed my first dog that I loved dearly loading the pharmaceuticals, heartworm, immunozations on. Thought I was being a good pet parent. I was wrong and learned the hard way. The second dog I adopted lived to 19.5 years of age and he was a 45 pound dog. Never had any problems with him and once he got his initial immunozations, he never received another, ever. Healthiest dog I had, of course, I also fed him super high quality human food. Made all the difference.

    1. Sherrie Ashenbremer

      What do you feed your dogs, if you don’t mind my asking. I have five dogs, one of them (10 pound Shih Tzu named Bailey) is very sick with what the vet calls allergies. His skin is red, very dry, his skin is flaky like he has dandruff, (very bad) and he has a very strong smell. I have tried several foods, Stella & Chewey, Caru, Allprovide, Evermore, he is no better. He has been to a dog dermatologist for over a year. He gets two allergy shots a week, has been on steroids, Apaquel and a few other strong meds. I am at a loss.

      1. Ian

        Dear Sherrie, Dr Cathy and Susan have an excellent pet food cookbook that is now in second edition. I would try their recipes and give him real food, I think a lot of dog allergies are really allergies to adulterated/contaminated food not to the particular food itself (i.e. mycotoxins in spoiled grain used for pet food etc.)

        1. Sherrie Ashenbremer

          Ian, Do you know the name of the book or where I can buy a copy? I will give it a try

          1. Susan Thixton

            Thanks Ian – this second edition went through a publisher, Amazon is a great way to purchase.

          2. Sherrie Ashenbremer

            Thank you I will be ordering a copy of this book tomorrow

      2. Renee

        Sherrie: It sounds like a thyroid issue because of hair loss and dry skin. What do you feed your dog now? I’m just a dog mom. Fifteen years ago, my dog had allergy issues. The vet said to look for one unique protein (i.e., duck, salmon) and one unique carb (i.e., sweet potato). That seemed to do the trick. Today it’s easier to find such foods. I began reading labels from that point on.

        1. Ian

          Sherrie and Renee, I can share my experience which may not be true for your dog. I had an older female dog that tested as thyroid deficient and was started on thyroid supplements which I was informed she would need for life. She was on them for a couple of years with regular testing to determine the amount needed. After switching from commercial pet food to Cathy and Susan’s Dinner Pawsible recipes, I took the dog back in (as I recall it was about 4 months after the switch to real food) and had her tested again and the vet said she no longer needed supplementation and weaned her off it completely. She had normal thyroid levels from them on. He had no explanation. I did— real food. If you are considering trying real food for your Shih Tzu you are in luck that he is only a 10 pound dog, this makes it much simpler and affordable to feed real food. I wholeheartedly encourage you to make the switch and re-evaluate his health in 6 months.

        2. Sherrie Ashenbremer

          Do that, he has had rabbit, he has had kangaroo (before you couldn’t buy it) he has had pork, chicken, venison. Tried them all

      3. Cathy Alinovi

        You might consider having him tested for SIBO = small intestinal bacterial overgrowth. It is a blood test – the lab of choise is Texas A&M GI lab.

      4. Diane


        How much have you vaccinated your dog? Vaccines are the biggest cause of allergies, making them almost impossible to cure. A raw diet would be the best type of diet, I would avoid chicken and beef to see if that helps. Consider supplementing with anti-oxidants, especially Vit C, it’s a histamine scavenger. Other anti-oxidants are CoQ10, curcumin, Vit E Other things to calm down the immune system such as Transfer Factor, DMG (which supports glutathione – body’s anti-oxidant system). The skin is just a symptom of what is going on inside, which is immune dysfunction.

        Have you treated him homeopathically? Helping him detox would be something to consider, homotoxicology is a safe way to do that. Many times that smell is from a buildup of toxins, what I call doggie odor. As someone else mentioned having a full thyroid panel done would be wise. Consider a C-Reactive Protein test to see how much inflammation he’s dealing with, would also be a nice way to gauge how well the antioxidants are working too.

        1. Sherrie Ashenbremer

          where do I get these anti-oxidants?

          1. Diane

            Hi Sherrie,

            You can buy antioxidants in many places, I prefer to shop online, The Vitamin Shoppe or my local health food store. Almost all Vit C is made in China, from corn (GMO), I’ve been told the process eliminates the issue of GMO, but this was coming from the manufacturer. I buy primarily from The Vitamin C Foundation, made in the US, non-corn/GMO.

            Back to the issue of vaccines, ask your vet for a waiver for the rabies, he/she should be willing to do this, since your dog is not healthy and should never be vaccinated again.

            Here are a few sources for antioxidants:

            This Vit E contains selenium, also very important nutrient:

            I buy this Vit C too, this is sodium ascorbate, so it’s buffered, ascorbic acid is sour, our dogs don’t mind it, but our cats do. I would start with at least 2000mgs, 1000mgs AM & PM.

            This is the curcumin I use:

        2. Sherrie Ashenbremer

          Thank you, I had no idea Vitamin C was made in China??? I hate that, but I will get some of this going for him. Thank you so much for getting back to me.

      5. Lynne

        Be careful with the steroids and allergy shots. Made the mistake of using both on my precious Jack Russell and I’m sure it shortened his life.
        You get get homemade food recipes and information from Dr. Basko.
        His book has a wealth of information about the importance of feeding our pets a natural

      6. Bette

        Hi Sherrie,
        I too had a Shih Tzu with skin problems. He would scratch and chew himself raw all over. I tried every remedy my vet, health food store and pet food store had to offer, but none of them worked for long. By chance I read an article by a woman who had great success treating her Shih Tzu with olive oil. I started adding a few teaspoons daily to his food. Within a week his condition started improving.In a matter of a few weeks his dry skin condition subsided, the redness went away, he stopped scratching and chewing himself and his dry hair became soft and had a wonderful sheen. He also had a major personality change as he no longer was in constant discomfort. He became calm, very loving and friendly to all.
        This is definitely worth a try. Good luck.

        1. Sherrie Ashenbremer

          I will try that. About how much Olive Oil? I currently give Bailey Salmon oil in his food.

        2. Sherrie Ashenbremer

          I tried that tonight, I added a teaspoon of Olive Oil to his dinner. I used the same Olive Oil I use to cook with it that ok?

      7. Karen Mitchell

        Hi Sherrie,

        I’m not a vet, I’m an advocate of the Prey Model & Biologically Appropriate Raw Food Diets and run a Facebook Group As Nature Intended. I’ve had holistic vets, researchers, trainers, breeders, whisperers, nutritionists and, of course, carers from all over the world join the group.

        If you’re looking for ways to help heal your long life friend, then removing all harmful toxins from their body, making a few changes in and around the home while feeding them one of these diets is certainly a good start. Maybe you have tried without success, there are some techniques that you can try. Perhaps your after some advice on when and what to feed, or considering on making the transition, or you’re looking for guidance or hints and tips on how to make the transition. If you wish to learn the benefits of foods suitable, how to prevent and treat different ailments, alternative medicine in treating and prevention and much more, then this informative group is there for you and your pets, 24/7

        Search As Nature Intended in Facebook, or message me in FB.

        1. Ian

          Hi Karen, I’m pretty ignorant about raw food diets but I have the following opinions which I welcome your feedback on:

          small indoor dogs: best/easiest diet is cooked (whole human grade) foods due to small dogs difficulty chewing larger bones, messiness of feeding raw indoors

          larger outdoor or at least “fed outdoors” dogs: raw food diet since the larger dogs jaws/teeth are better at chewing up raw bones and the messiness of a dog chewing on a raw piece of meat and bone is mitigated by their being outside the house

          Your opinion?

        2. Sherrie Ashenbremer

          Karen Mitchell, I will contact you, or send you a message tomorrow about more information on this diet. Bailey looks so bad, he is beat red and has yellow (where the skin has died) skin flaking off of him. And he smells like, kind of like urine. Very strong, I am not complaining I am just trying to give details. Thank you everyone for all the good information.

        3. Erica

          Hello! in trying to look for you on FB i seen several groups called As Nature intended- They all appear to be human based. there is one that said give a dog a bone- Is this your group?

          Thank you!
          Erica Johnson

    2. JAN


    3. Linda Vick

      Good for you, Darlena! The more we speak up for our fur kids and learn from each other, the better.

    4. curvecrazy

      Are you saying to not even give anti heart worm meds? In my area the critical infection times would be June-august. We’re doing the standard immunizations and rabies upcoming. My standard poodle is about 14 weeks now.
      Vet seems to think I should be giving him “Interceptor” once a month forevermore…… It appears to me to be a monthly “vet visit” thing along with the $7.50 a dose charge. I read online that monthly isn’t necessary and those in the know give mess 6 weeks after fret mosquito appearance in their area. Then stop monthly med dose at first frost. We have somewhat high mosquito populations here and ticks/Lyme disease.
      I admit I’m kinda bothered that my vet plied me on the “Interceptor” tablet last week of January without a mosquito in sight and it will be months before the 57* temperatures provide suitable. And I can’t get the meds without an Rx which the online supplier sent my vet a request and was refused…….
      I was wholly uneducated but now read that monthly heartworm is unnecessary. I’m beginning to question the vet with her $1M fancy “facility” which on simple evaluation >>>> I’m paying for so much of the charges are paying for her EGO TRIP FACILITY vs actually doing my puppy any good and maybe toxifying the dog with excessive worm preventative causing possible harm?
      Opinions appreciated…………

  12. Linda H

    For the people worried about the effects of ivermectin on collie and collie type dogs, this is an excellent article with links for a genetic test is you are worried about giving your dog ivermectin.

    On another matter, it is very difficult to overdose a dog on ivermectin. The first vet that informed me of how to use ivermectin said someithing like, “It’s hard to overdose a dog on ivermectin.” when I called him in a panic because I accidently gave an 8 week old 5 lb puppy 1/2 cc of ivermectin instead of 1/2 of 1/10 cc. Puppy was fine and lived to 14 1/2.

    1. Debbie

      Linda H., Actually i am not sure that is correct. I myself have a pitbull/am bulldog mix. I gave her a dose of ivermectin and she had a severe allergic reaction to it and almost died. She does not have the MDR1 Gene. i had her tested. But allergic reactions can occur. so when giving, watch the dog for the first 12 hours for sure and up to 72 hours. its crucial when you give straight ivermection. I had given many doses to my other pitbull mix without ANY issues at all. And both also were treated for heartworms. One using straight ivermection and doxy and the other using doxy and heartgard only. both became negative at the same amount of time. Now that i have more knowledge, My dogs or any dog being treated by me for heartworms or rpevention will NEVER get ivermectin again. i will use only natural remedies. Also at Effective Pet Wellness, they have worm killers including heartworms. even treatments for lyme and a few other diseases. 100% guaranteed. There are so many options out there its off the charts. No need to ever use drugs again. I even can treat canine arthritis without drugs. you must do alot of research. thats how you find answers. read read read.

    2. Susan Beals

      It is not hard to overdose a dog on ivermectin. Even dogs that do not carry the MDR1 gene can become seriously ill (to the tune of days or weeks in intensive care and tens of thousands of dollars) from eating feces of livestock recently wormed with ivermectin products. Do a web search for Laura Liebenow and Bristol. I don’t know if Bristol carries the MDR1 gene, although it is prevalent in Aussies. I also know of a Jack Russell who became very ill eating manure from horses freshly wormed with ivermectin. JRTs do not carry the MDR1 gene.

  13. Johanna

    Excellent article, Susan! After learning about how dangerous topical flea meds were years ago, I decided to take my dogs off of their heartworm meds as well. The responses from my vets were horrific- they were incredibly rude and hateful and made a point to make a scene in front of other clients so that hopefully I would feel shamed into putting them back on it. I didn’t, and my dogs are just as healthy as ever. I had been wanting to do it for years- I hated the idea of feeding them a monthly dose of poison, but the vets make you feel so afraid for questioning them. The truth is, once I started researching heartworm, I learned a lot that vets never tell their clients. Firstly, dogs in the wild (wolves, coyotes, etc) hardly ever succumb to heartworm, and only do when they are very sick to begin with. Otherwise healthy wild dogs eventually overcome the heartworm and then become immune against re-infection. So why are so many pet dogs getting heartworm? Probably because they are so sick from all the vaccines, pet food, and prescription meds. I found up-to-date maps online that assess the heartworm risk for each state/region and determined that, because of my location (northern IL), the fact that my dogs are very healthy with a real food diet and no synthetic meds, and that they are at very low risk because they are indoor dogs, I knew that the best thing would be to get them off heartworm meds altogether. Of course, we take precautions by spraying them down with Cedar Oil Spray (I use Dr. Ben’s) before going anyplace “buggy”, and avoid being outside in the morning or evening when mosquitoes are most active. I’m also excited to have recently found out about a study using ginger to treat heartworm infection. Apparently its just as effective at killing the worms as the traditional arsenic treatment, but without any of the harmful side effects. Unfortunately the study was from the 80’s I believe, and no research (that I know of) has been done to determine if ginger can be used to “prevent” heartworm infection. (here’s the link to the study I wish vets were doing more to educate owners on the truth about heartworm and their options for prevention/treatment, thank you for bringing this to people’s attention!

  14. Laurie Matson

    Johanna, you are so correct in everything you say!! Do you follow Dr. Will Faulconer by chance, the wonderful Homeopathic Vet in Austin Texas? He has a website and Facebook page called The Vital Path. He specifically says that Dogs that are repeatedly Vaccinated, treated with Flea and Tick Preventatives and Fed Commercial Dog Food are not healthy and Vital and that they are the Dogs that get Heartworm Disease!!! And Cedar Oil is supposed to be very effective as a Repellent. I just bought some repellent spray with the Cedar oil made by the Wondercide Company. In fact, they were just on Shark Tank tonight!!! They sell there wonderful products on they’re website and on I just love Dr. Faulconers advice and I subscribe to all his posts. More info on using Ivermectin sold for pigs would be awesome. The strength to buy and how many mil or cc to administer per pound of dog. I have no problem injecting it but need to know the strength and amount.

    1. Johanna

      Thanks for the tip Laurie! I hadn’t heard of Dr. Faulconer, but his site looks very informative. I just signed up to receive his newsletters. 🙂

  15. Debbie

    ok you all, STAY AWAY FROM MEDICATIONS SOLD FROM VET. All are toxic!!! Use Nosodes. I wrote a protocol on heartworm prevention and treatment. I live in Texas and I use only Heartworm nosodes. You all can google this stuff instead of someone looking for the links for you. come on. dont be lazy.

    I have many options listed with my protocol. I want to share my website link to help you all out. I DID ALL the work for you. so all you lazybones…here ya on and look for links at the bottom of that page for natural solutions. No I dont sell this stuff. I only offer it for info so pet parents.

    and Diane is correct. Raw diet, FILTERED fluoride free water, rabies only every 3 yrs. Make sure it is thimerosol free rabies. Titer for others. no flea and tick medications. Use Diatomaceous Earth for flea and ticks in yard. use half and half water and unfiltered apple cider vinegar and spritz your dog several times throughout the day if they are outside hanging out.

    I also have a list on all natural flea and tick products on my website.

    PEEPS, stay away from DRUGS. they are high risk to our pets. And so is the crappy kibble. homemade diet is best with the correct supplements. Yep got a list for that too. Its as easy as pie to do all of these things.

    1. Karen Mitchell

      Running a Facebook group I’m always looking for trusting sites and articles. I have enjoyed learning from your site in the past. Thank you

    2. Diane

      Hi Debbie,

      I agree with the fluoride free water, but mineral water would be best. Depending on your filter you may not be getting all the fluoride out, mercury, aluminum, etc. If you’re buying filter water you have to trust it’s that, but having it tested would be a good idea.

      The rabies vaccine is the most reactive of all vaccines, thus, it causes the most damage. “TF” is not reassuring to me, vaccine manufacturers are anything but transparent. Vaccine manufacturing is a multi-step process, the first step in the process doesn’t have to report to the second step what is in their toxic brew. Currently our Gov’t has allowed Big Pharma to list vaccines “mercury free” if it’s not used as a preservative. Actually they never did take out the mercury because they can state mercury free if it falls below a certain level. Animal vaccines are more unregulated than human vaccines, so it’s anybody’s guess what’s in them, BTW, the vaccine manufacturers don’t know either, vaccines are extremely contaminated.

      Vaccines are about money, that’s it, they fall under The Germ Theory, which was disproven a long time ago. Conventional medicine is about sick care, not health care, vaccines are the primary tool for ensuring a pipeline of chronically sick individuals, good for profit, not good for the individual.

  16. Erica

    Hello Dr. Cathy Alinov.
    What are your thoughts on testing for heart worm 2x year and treating only if necessary rather then giving a monthly “treatment” and exposing them to unnecessary chemicals on a monthly basis?

    Thank you
    Erica J.

  17. Dr Cathy

    Hi Erica
    Your question is well timed – someone just asked me essentially the same thing off-line!
    Heartworm tests don’t detect infection until the infection has been present over 6 months. The heartworm tests detect heartworm infection once the adult worms have started breeding in your dog. This means if you test your dog every 6 months, and do all the other awesome, healthy pet things discussed above, and your dog tests heartworm positive, the infection is likely to be 6-11 months established. This means adult worms will have been causing heart damage for 6-11 months.
    I do think minimal heartworm prevention and testing twice a year is a great idea. Those who live in low-risk areas might give a heartworm preventative twice – half-way through the summer and again after hard frost. Then test in the fall and spring. HOWEVER – this is not FDA approved. 🙂
    For those who live in high-risk areas, there is enough anecdotal evidence that the preventatives work if given every other month. (In fact, Advantage Multi has a new advertising campaign telling pet owners it’s ok if you miss a month – just apply and get back on schedule!)
    One note about cats: they get heartworm infections too. Because they rarely have multiple adults, the heartworm test is quite poor at detecting infection. Any of the above discussions would relate to cats as well. Just be sure NOT to give dog medication to cats – not all are the same – without asking an expert first.
    Hope that helps with your question.

  18. Mary Blemler

    What are your thoughts on the 6 month heart worm shot? My malshi has been gettin this for a few years.
    Thank you,

  19. Dr Cathy

    Proheart 6 is wonderfully convenient (it is licensed for 12 months over-seas thus called Proheart 12). Dogs were having side effects – lethargy, not eating, seizures and some deaths. The side effect rate was high enough it was actually pulled off the market for re-evaluation in the United States. The side effects were worse for little dogs and worse when the injection was given at the same time as vaccinations. When Proheart 6 returned to the market, it was with conditional approval – dogs had to have bloodwork performed before the injection and it could not be given near vaccines. Makes you wonder what the real problem was: vaccines or a chemical that lasts in the body for 6-12 months? I’m not a fan.

  20. Trouble

    I’m not sure if this was already addressed at some point within the comments… And I know my question here is a bit delayed (about a month-ish delayed, actually, given when this post was made, lol), but… I’ve worked in the pet industry a long time, and used to work sort-of with a vet’s office (worked in a pet store that also had a vet’s office in it – I’m sure the list of businesses like that is small, so probably not hard to narrow down, lol), and I was always asking the vet’s there questions, trying to learn as much as I could about procedures, medications, diseases, disorders, treatments, preventatives, etc. etc. You get the idea. Aaaaaanyways… I was told that with Heartworm… If your dog does have heartworm (meaning would produce a positive heartworm test result), that giving them the “preventative” heartworm medications would actually be harmful to your dog, and could potentially kill your dog. I was told that the heartworm, at this stage in their life-cycle, releases a toxin into the …heart valves, I think it is?, when they die off this way (from the preventative meds), and that’s why the treatments they do instead, once your dog tests positive for heartworm, are different than the preventative, and probably why they’re so costly too, I’d imagine. I’m not sure what the actual treatment is that vet’s do, if a dog tests positive for heartworm, but… I’ve always been told that it’s different than just giving them the heartworm preventative. Which is why they want your dog tested every year, before you get more heartworm preventative stuff.

    Please let me know if I’ve been misinformed about any of this, or correct any of it that may be inaccurate in some way… I’m actually needing to get something for heartworm “preventative” for my dog… She’s due for a yearly heartworm test, and with summer coming up, I’d feel more comfortable with her having some form of protection. But, would like to know which “preventative” product is best. Is there any product that only does heartworm, and not all that other crap – the intestinal parasites and whatnot?

    I also was told by the vet there, where I used to work, that teeeechnically, you could get away with every other month, but they don’t advise it, and they didn’t want me advising that to customers (of course… would cut into their profits, lol), and could be risky if people push the envelope on it, I’d imagine.

    1. Dr Cathy

      You ask some great questions!
      I learned the same thing when I graduated veterinary school: it’s not safe to put heartworm positive dogs on heartworm prevention without treatment. But, for the dog owner who cannot afford the treatment, veterinarians will put the dog on year-round preventatives and wait for the adults to die. It’s contradictory.
      And, yes, even Advantage Multi is now saying if you miss a month, it’s ok – restart the medication. This essentially means every other month seems to work.

  21. Jane

    ” Do not give ivermectin to Collie breeds. Collie dogs cannot process ivermectin.” I heard this statement many years ago, and thought that nowadays this was a myth that was debunked. Yes, it can be toxic but from what my vet told me ivermectin dosage in preventatives are very, very low, like 20 times lower or something along this range. The problem is mostly when ivermectin is given in high doses as when to treat demodex or sarcoptic mange. Is this article taking an excessively cautious approach or is my vet being negligent in prescribing it for my collies? She said it is safe at such a low dose and I even found a study stating that!

    1. Dr Cathy

      It is not a myth – Collies cannot breakdown ivermectin. The heartworm prevention manufacturers feel their product is low enough concentration to be safe to most Collies. Who wants to have the one Collie for which it isn’t safe? Why risk it?

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