Heartworm Disease – Deadly to Dogs

We have diagnosed 6 cases of heartworm disease in the past 6 weeks. All of these dogs looked normal but a simple ten minute blood test told a different story. Left untreated, these dogs could develop heart disease. The heartworms cause damage to the heart which can lead to heart failure and death.

Heartworm is spread by mosquitoes and initially causes no symptoms at all. So if you are late giving prevention and your dog gets bitten by an infected mosquito, there may be no clinical signs until it is too late.

Luckily testing and prevention is easy. If your dog is not receiving any heartworm prevention OR if you have EVER been late giving a monthly preventative, then a heartworm test is required. It takes 2 drops of blood and ten minutes of time.

There are many different prevention products on the market. These can be divided into 2 groups:

  1. A yearly preventative injection.
  2. Monthly options (tablets, chews, spot ons)

The monthly options MUST be given on time. Even a few days late can open up a window in which your dog can become infected with deadly heartworm. 40% of heartworm positive dogs are on owner given monthly preventions. This isn’t because the preventions don’t work, but because we are human and can easily forget a dose.

For this reason we recommend the yearly heartworm preventative injection. One trip to the vet once a year and you never have to worry about heartworm again. It is then our job to remind you when your pet is due for the next dose.

Does your dog need a check for heartworm? If in doubt get them tested TODAY.

Heartworm, or Dirofilaria immitis, is a parasite that is spread by mosquitoes, so your pet does not even need to be in contact with other pets to become infected!


Heartworm has a complicated life cycle.  Infected dogs have microfilaria, an immature form of heartworm, circulating in their bloodstream.  Microfilariae are sucked up by mosquitoes when feeding on the blood of infected dogs. The immature parasite develops into a heartworm larva inside the mosquito, then a single bite from a carrier mosquito can infect your pet (dog or cat). As the worms mature in the heart they can cause a physical blockage as well as thickening of the heart and associated blood vessels.  In the early stages of infection there may be no visible signs, however, infection may eventually lead to signs of heart failure (reluctance to exercise, lethargy,coughing) and even death. Heartworm is present throughout most of Australia (except Tasmania and arid areas).

Thankfully, heartworm is very easy to prevent and should form part of your pet health care routine. We have very effective preventative treatment options available including tablets, chews, spot-on's, and even an annual injection for dogs administered by one of our vets. If your pet has not been on heartworm prevention we strongly recommend a heartworm test prior to starting a prevention program, followed by a repeat test 9 months after commencing prevention.

Please call us to discuss the best heartworm prevention for your pet.



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