Phone:02 9527 2604
'Compassionate care for you and your pet'
41 The Kingsway Cronulla NSW 2230

Heartworm, is it still a problem?

Pet dog recovering from heartwormWherever there are mozzies, there is the risk of heartworm infection in our pets.
Here at Cronulla Veterinary Clinic, we can protect your furry family member against the dreaded heartworm disease and other parasite infections.

What is heartworm?

Heartworms are long worms (up to 30 cm long!), living in the heart and large blood vessels around the heart. They are transmitted through mosquitoes. They live in mosquitoes as larvae, and when the mozzie feeds on our dog or cat, it injects the larvae under the skin. The larvae then make a track through the tissues to the heart where they mature to adult larvae. The adult worms mate and produce larval offspring, called “microfilaria”. The microfilaria circulates in the bloodstream of the infected pet. Mosquitoes biting an infected animal ingest the microfilaria, inside the mozzie the larvae mature, and the larvae are once again injected into a new pet as the mozzie feeds again.

What can be some of the symptoms of heartworm disease?

As heartworms damage the heart, lungs and blood vessels around the heart, common signs can include:

  • Coughing
  • Inability to exercise as usual
  • Weight loss
  • Listlessness
  • Laboured breathing


Cats can have symptoms that mimic cat asthma. Cats are not as good a host as dogs when it comes to heartworms, but if the heartworm larvae do manage to develop into adult worm(s) the diagnosis can be more difficult, and the treatment has more risk of complications. Heartworm disease can be deadly, especially for cats!

Some important heartworm facts:

Treatment needs to be given all year round, because infection by mosquitoes is possible all year round, not just in the warmer months. This is true even for pets who don’t go outside or socialise with other animals.

In other heartworm regions of the world, such as the USA, where the 12 monthly heartworm injection is not available, routine yearly heartworm testing is a must, even for pets already on heartworm prevention. This highlights the serious nature of potential heartworm infection.

Even in Australia, the best standard of care is yearly preventatives and yearly testing for heartworm.

Wildlife, such as foxes, and stray/feral animals are susceptible to heartworm as well, so even in a perfect world where all our pets are on constant prevention, we never lose the sources of the infection completely!

How common is heartworm?

Surveillance programs in Australia have noted a rise in heartworm infections in recent years, with over 1350 positive cases reported to one program since 2014! Shockingly, over 40 % of these cases recently diagnosed with heartworm disease were on a monthly heartworm prevention, which means somehow they didn’t get all their heartworm prevention doses on time, possibly due to the pet not taking the tablet or chewable properly, or vomiting it up, or the medication being given too late.

Here at Cronulla Veterinary Clinic, we can take the worry out of remembering to dose your pet monthly for protection against this potentially deadly disease, by offering a yearly slow release heartworm injection and reminder system. Ask our friendly staff about this easy injection. Remember to also ask us about our special “Paw Club Care” program for a more affordable way to parasite treat your furry child☺