Many dog owners know very little about canine heartworm. So, as pet professionals, it’s important to help pet parents to understand the risks, common signs and preventative steps.

Certainly, the prevalence of canine heartworm in Australia appears poorly understood. At one time, it was thought to be endemic to South Australia. However, more recent surveys on canine heartworm suggest this isn’t the case any longer.

The facts about heartworm

While most people have heard of heartworm, very few really understand the basics, let alone every thing there is to know about it. As such, sharing a few facts about canine heartworm can be really helpful.

Indeed, I have a dog myself (Chewie, the border terrier) but I didn’t realise that heartworm is spread by mosquitoes, until recently.

In fact, a survey of Australian pet owners revealed that 1 in 3 dog owners believe that canine heartworm is spread by birds and through food!

In reality, just like malaria, canine heartworm is transmitted by mosquito bites. The infected mosquito will bite a dog and, in doing so, infect them with heartworm larvae.

The larvae remain in the tissue for a few days before travelling to the heart to mature. As the adult heartworm develop (this can take approximately six months), they impact the free flow of blood between the heart and lungs, causing serious damage.

The negative affects of heartworm include lung disease, heart failure, organ damage and even death.

Given the nature of mosquitoes, certain environments and areas of Australia may pose a higher risk. This includes:

  • Areas/states were there are high temperatures and high humidity (such as Northern Queensland and WA, for example)
  • In times of very high rainfall, flooding and storms
  • Once rural areas that have recently been developed for urban expansion

cute brown dog lying on blanket, canine heartworm symptoms

Image source: Ruby Schmank on Unsplash

Canine heartworm symptoms

It’s likely that infected dogs will show no clinical signs of heartworm during the first few months as the worms are still growing and reproducing. However, once the disease progresses various symptoms can appear. Vet Voice notes he following common signs of canine heartworm disease:

  • Intolerance to exercise
  • Lethargy and weakness
  • Dry, persistent cough
  • Weight loss

Heartworm prevention

Heartworm doesn’t discriminate, it doesn’t matter what size or breed the dog – prevention is the key.

What’s more, ‘timely’ preventative treatment is important! Findings from the Heartworm Surveillance Project a few years ago revealed that 64% of Australian dog owners admitted administering monthly prevention after it was due and 5% administered monthly prevention more than one month after it was due.

The Project also found that 40% of reported heartworm cases were in dogs on monthly heartworm tablets or spot-ons.

In cases where the dog is not currently on any heartworm prevention, the best action is to suggest an initial heartworm test. Following this, preventative measures can be decided on and put into action.

There are various preventative treatments available to pet owners. Aside from the annual heartworm prevention injection, there are monthly preventatives that come as a tablet or spot-on treatment.

However, it’s imperative to advise owners that one missed monthly dose can put their dog at risk of heartworm.

TIP: A comparison table of the parasite treatments available (which includes heartworm) in Australia can be found here.

black and grey curly-haired dog

Image source: Gary Samaha on Unsplash

Trusted information for owners

As a pet professional you’re a great source of trusted information and advice for pet owners on a wide range of issues and topics. Having the know-how on a wide range of health issues is a great conversation starter.

Without a doubt, selecting an appropriate heartworm treatment can be tricky. Not only are there quite a few preventative products on the market, many treat other parasites too. What’s more, some need to be taken daily, while others are monthly.

Forgetful pet owners may benefit from the annual injection. You can suggest they combine this with their dog’s yearly vet check-up. For daily and monthly treatments, pet owners may like to set a reminder or alarm on their phone.

Particularly for daily dosing, you can suggest they leave the treatment somewhere where they will be reminded to administer it on time; for example, next to the kettle if they make themselves a coffee or tea every morning.

There’s really no one-size-fits-all approach to heartworm prevention. However, talking through the different products and alternative regimens may help pet owners decide which method works best for them and their canine chum.


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Leanne Philpott

Leanne is a professional freelance writer at contentchameleon.com.au. She works alongside her fur pal Chewie (a border terrier) to deliver information that is accurate and relevant to our readers.