Heartworm dog symptoms

There are two broad categories of worms that may affect our pet dogs and cats, heartworm and intestinal worms.  Please see our intestinal worm page for more information. This page addresses heartworm dog symptoms only.

About heartworm

Heartworm, or Dirofilaria immitis, is a parasite that is spread by mosquitoes, so you 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 earlystages 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).

Heartworm dog symptoms

Pay attention to the following heartworm dog symptoms:

  • Persistent cough (not a strong cough like kennel cough, more a dry and persistent cough)
  • Difficult or laboured breathing
  • Lethargy
  • Weightloss
  • Enlarged chest with bulging ribs

The heartworm lifecycle in dogs

This image shows the stages of heartworm in dogs:

Heartworm dog symptoms

Treating heartworm in dogs

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, the most convenient and easily administered being an annual injection called Proheart 12.

Proheart is the recommended treatment of Heartworm, as it ensures that no monthly prevention is missed, unnessarily exposing your dog to heartworm and potential death.

There are also monthly tablets, chews, spot-on's available. If your pet has not been on heartworm prevention we strongly recommend a heartworm test prior to starting a prevention program - starting any heartworm prevention without this test may result in fatality.

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

"Heartworm dog symptoms", written by Jenny M.