• Testing for Heartworm Disease and When It’s Necessary

  • Testing for Heartworm Disease and When It’s Necessary
  • By: Dr. Clayton Greenway, B.Sc., DVM | Nov 2, 2016

  • Dr. Greenway discusses the benefits of testing for heartworm disease in dogs and when it is necessary. Other topics covered in this video include medication failure, prevalence, adverse reactions, cost, risks, blood tests and heartworm disease.


    I’m Dr. Clayton Greenway with healthcareforpets.com. I wanted to talk about testing for heartworm disease. I actually get a lot of questions about this and a lot of clients wonder if it’s necessary or not, particularly the clients that are already preventing that disease with medication.

    So heartworm disease can be contracted through here in Toronto, Canada the summer months but in warmer climates it could be contracted at any time of year.

    So if you’re using the prevention, why is it that you have to test to see if they have heartworm disease or not? Well here’s the answer, we tend to give out this medication, this preventative medication for heartworm disease but we have to make sure that that dog is negative for heartworm disease first, that it doesn’t have the disease because if you give that medication, it could cause either an allergic reaction as it kills some of the worms that that dog may have or it could kill them fast to the point that they could cause blockages in the vessels where they live.

    Now some of this medication is safer than others and you’re going to want to talk to your veterinarian about that but if you use the medication the year before or through the year, then your risk of having heartworm disease in your dog is extremely, extremely low and you may consider declining the test. At our practice we always have people sign a waiver for that because we are effectively giving a medication that may harm their dog if it has heartworm disease.

    Now keep in mind you may not have applied all the doses of the heartworm medication, some may have washed off if you’re using a transdermal form of it that you put on the skin. It may not even have been formulated right at the company so there’s multiple reasons why there could have been failure of that medication and your dog could have contracted heartworm disease even though you were giving it or thought you were giving it so keep that in mind, it’s all about risk. So if you think that you effectively used it, maybe you look at declining that test. My recommendation would be to always do the test because it doesn’t interfere with your dog’s health to do the test, it’s a blood collection and that’s really not a significant enough reason not to do a test that may have a major impact on your dog’s health.

    The other aspect is the cost of it and you’ll have to judge that for yourself as to whether you want to pay for that test based on the risk of them getting that disease and how well you prevented it in the past. This is something that I think a lot of clients have difficulty deciding about, about what level of care they want to implement based on cost for things like heartworm disease. It’s important that you work with your veterinarian about how you feel about that and make sure that they’re recommending the right thing for you and your pet.

    There’s only one last point I would mention, here in Toronto, Canada we’re seeing a real increase in a problem with ticks and ticks carry Lyme disease and in fact, when we do a heartworm test we also test for Lyme disease and your vet may do the same and that’s something I’d really want to mention about heartworm testing. It’s very easy to perform that test as well and you’ll find more information about ticks and Lyme disease on our website.

    Testing for Heartworm Disease and When It's Necessary
    Testing for Heartworm Disease and When It's Necessary

    Dr. Clayton Greenway discusses the benefits of testing for heartworm disease in dogs and when it is necessary.

    Disclaimer: healthcareforpets.com and its team of veterinarians and clinicians do not endorse any products, services, or recommended advice. All advice presented by our veterinarians, clinicians, tools, resources, etc is not meant to replace a regular physical exam and consultation with your primary veterinarian or other clinicians. We always encourage you to seek medical advice from your regular veterinarian.

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