Five heartworm prevention products are approved for dogs in Australia in 2026, and the right pick depends on your dog's tick exposure, temperament, and how reliably you can stick to a dosing schedule.
Best overall: Simparica Trio. Best for zero-dosing compliance: Proheart SR-12. Best budget option: Heartgard30.
- Simparica Trio is the best heartworm prevention for dogs in Australia 2026 for one chew covering heartworm, fleas, ticks and worms.
- Proheart SR-12 removes at-home dosing with a single vet-administered injection lasting 12 months.
- NexGard Spectra adds stronger paralysis tick cover for dogs walking bushland trails on the Northern Beaches.
- Heartgard30 is the budget monthly tablet for low-exposure dogs needing heartworm-only cover.
- Advocate suits dogs that refuse tablets, applied monthly as a topical spot-on.
Why this matters
Heartworm (Dirofilaria immitis) spreads through a single mosquito bite, and the larvae take roughly six months to mature into adult worms living in the heart and lungs. Untreated heartworm disease is fatal, and treatment for an established infection is far harder on a dog than any prevention product.
Sydney's humid climate keeps mosquitoes active for most of the year, which is why the vets at Two by Two Vet in Balgowlah recommend continuous, year-round heartworm prevention rather than seasonal dosing. Skip a dose for a month or two and most vets will want a heartworm blood test before restarting — giving a monthly product to a dog that's already infected doesn't clear the infection and can trigger a dangerous reaction as the worms die off.
What makes the best heartworm prevention
- Protection window and compliance risk — a 12-month injection removes the chance of a forgotten dose; a monthly chew or topical doesn't.
- Spectrum of cover — heartworm-only versus combined flea, tick and intestinal worm treatment in one product.
- Regional tick relevance — paralysis tick exposure is real for dogs walking bushland reserves around Manly and Balgowlah.
- Administration method — chewable, topical, or injection needs to match the dog's temperament and your routine.
- Vet oversight — a heartworm test is required before starting most products, and several are prescription-only.
- Breed safety — some actives need extra caution in MDR1-mutation breeds like Collies and Border Collies; a vet should confirm dosing.
Heartworm prevention for dogs in Australia: at a glance
| Product | Best for | Standout feature | Key limitation |
|---|---|---|---|
| Simparica Trio | All-in-one monthly cover | Heartworm + fleas + ticks + worms in one chew | Strict monthly timing required |
| Proheart SR-12 | Zero-dosing compliance | 12-month protection from one injection | No flea or tick cover |
| NexGard Spectra | Bushland or tick-heavy dogs | Broad tick spectrum alongside heartworm | Monthly chewable, same compliance risk |
| Advocate | Tablet-refusing dogs | Topical spot-on, no swallowing | No tick cover, weakened by swimming |
| Heartgard30 | Budget, low-exposure dogs | Heartworm + roundworm/hookworm only | No flea or tick protection |
1. Simparica Trio: best heartworm prevention for dogs needing all-in-one parasite cover
Simparica Trio is a monthly chewable combining sarolaner, moxidectin and pyrantel to cover heartworm prevention, fleas, ticks (including paralysis tick) and intestinal worms in a single dose.
Simparica Trio pros:
- One chew covers four parasite groups instead of juggling separate products
- Palatable formulation improves owner compliance
- Covers paralysis tick, relevant for dogs walking bushland trails on the Northern Beaches
Simparica Trio cons:
- Monthly dosing means a missed month opens a gap in heartworm cover
- Not suitable below the label's minimum age or weight — check with your vet
Simparica Trio is a prescription product dispensed through your vet.
Best for: owners who want heartworm, flea, tick and worm cover handled in one product. Verdict: Buy.
2. Proheart SR-12: best heartworm prevention for dogs needing zero-dosing-risk protection
Proheart SR-12 is a single injection, administered by a vet, delivering 12 months of continuous heartworm prevention through extended-release moxidectin. There's no at-home dosing at all.
Proheart SR-12 pros:
- Removes the risk of a missed dose for a full year
- One vet visit replaces 12 separate monthly treatments
- Suits owners who travel or struggle to remember monthly doses
Proheart SR-12 cons:
- Covers heartworm only — fleas, ticks and intestinal worms still need separate treatment
- Requires a confirmed negative heartworm test before the first injection, plus an annual vet visit
Proheart SR-12 is vet-administered only and not available over the counter.
Best for: dogs whose owners want heartworm prevention locked in for 12 months without remembering a single dose. Verdict: Buy.
3. NexGard Spectra: best heartworm prevention for dogs in tick-heavy bushland areas
NexGard Spectra is a monthly beef-flavoured chewable pairing afoxolaner and milbemycin oxime, covering heartworm prevention alongside a broad tick spectrum, fleas, and roundworm, hookworm and whipworm treatment.
NexGard Spectra pros:
- Strong tick spectrum suits dogs regularly walked through bushland reserves
- Most dogs take the chew readily
- Covers four intestinal worm types alongside heartworm
NexGard Spectra cons:
- Monthly dosing carries the same compliance risk as any chewable
- Not a substitute for manual tick searches after bushwalks in high-risk seasons
NexGard Spectra is a prescription product dispensed by your vet.
Best for: dogs with regular bushland or off-leash exposure where paralysis tick risk is high. Verdict: Buy.
4. Advocate: best heartworm prevention for dogs that refuse tablets
Advocate is a monthly topical spot-on combining imidacloprid and moxidectin, applied to the skin at the back of the neck. It covers heartworm prevention, fleas, some intestinal worms and sarcoptic mange mites.
Advocate pros:
- No swallowing required, useful for dogs that spit out chewables
- Covers mange mites alongside heartworm and fleas
- Simple monthly application
Advocate cons:
- No tick cover — a separate flea and tick prevention product is still needed in tick-prone areas
- Effectiveness can drop if the dog swims or is bathed soon after application
Advocate is a prescription product available through your vet.
Best for: dogs that fight chewable tablets or have a history of mange. Verdict: Buy for tablet-refusing dogs, Skip if tick cover is the priority.
5. Heartgard30: best heartworm prevention for budget-conscious owners of low-exposure dogs
Heartgard30 is a monthly chewable tablet built on ivermectin and pyrantel, delivering heartworm prevention plus roundworm and hookworm treatment. It's a narrower-spectrum, long-established formulation.
Heartgard30 pros:
- Narrower spectrum keeps the chew simple for dogs with sensitive stomachs
- Long-documented safety record
- Straightforward when fleas and ticks are already covered by a separate product
Heartgard30 cons:
- No flea or tick protection, so it only suits dogs already covered elsewhere for those parasites
- Ivermectin-based actives need vet confirmation of safe dosing in MDR1-sensitive breeds like Collies
Heartgard30 is a prescription product through your vet.
Best for: low-exposure indoor dogs already using a separate flea/tick treatment. Verdict: Hold — fine for low-risk dogs, but most Northern Beaches dogs need tick cover too.
How we ranked these
Ranking weighs compliance risk first, since a missed monthly dose is the most common reason heartworm prevention fails in practice, followed by parasite spectrum, regional tick relevance, and how well the administration method fits the dog. Heartworm-only products dropped in rank once tick exposure entered the picture, because most Northern Beaches dogs need both.
“A missed month of chewable heartworm prevention is the most common reason it fails — a 12-month injection removes that risk entirely.”
Which heartworm prevention should you choose?
For most dogs on the Northern Beaches, Simparica Trio is the default pick because it covers paralysis tick alongside heartworm prevention in one monthly chew. If remembering a monthly dose is the real barrier in your household, Proheart SR-12 removes that problem completely with one injection a year. Budget-focused owners with a genuinely low-exposure, indoor dog can stick with Heartgard30, but pair it with a separate tick product if there's any bushland exposure at all.
Book a heartworm check
Confirm your dog is heartworm-negative before starting or restarting prevention.
FAQ
What is the best heartworm prevention for dogs in Australia in 2026?
Simparica Trio is the best all-round pick for 2026 because it covers heartworm, fleas, ticks and intestinal worms in one monthly chew. Dogs needing zero-dosing-risk protection do better with the 12-month Proheart SR-12 injection.
Is a heartworm injection better than a monthly tablet?
An injection like Proheart SR-12 removes the compliance risk of a monthly dose but covers heartworm only, while monthly chews like Simparica Trio or NexGard Spectra add flea, tick and worm cover. The better option depends on whether missed doses or parasite spectrum is your bigger risk.
How much does heartworm prevention cost for dogs in Australia?
Pricing varies by product, dog weight and your vet clinic, so check current pricing directly with your vet rather than relying on a fixed figure.
Do I need a heartworm test before starting prevention?
Yes, most vets require a negative heartworm blood test before starting or restarting prevention, especially after a gap of a month or more. Starting a product on an already-infected dog doesn't clear the infection and can cause a dangerous reaction.
Can heartworm prevention products also cover fleas and ticks?
Yes — Simparica Trio and NexGard Spectra combine heartworm prevention with flea and tick cover in one dose, while Proheart SR-12 and Heartgard30 cover heartworm only.
Is heartworm a real risk for dogs in Sydney and on the Northern Beaches?
Sydney's humid climate keeps mosquitoes active for most of the year, which is why continuous, year-round prevention is recommended rather than seasonal dosing.
What happens if my dog misses a monthly heartworm dose?
A single missed dose rarely causes infection outright since larvae take about six months to mature, but repeated gaps raise the risk and most vets will want a heartworm test before restarting.
One last thing
The six-month gap between infective mosquito bite and mature adult heartworm is why a single missed dose rarely means disaster — but it's also why vets treat repeated gaps seriously rather than shrugging them off. If your dog has gone more than a couple of months without a dose, book a heartworm test before restarting any product; it's a five-minute blood draw that avoids a dangerous reaction down the line.
