What is the best heartworm treatment for dogs? [2020]

LAST UPDATED 6 JANUARY 2020

This article is written by Pet Circle veterinarian, Dr Carla Paszkowski

Heartworm prevention is one of the most confusing topics surrounding dog ownership. Not too long ago, dog owners had only one choice to protect their dog against heartworm: a daily tablet.

Nowadays, thanks to advances in veterinary medicine, there are a whole variety of ways to protect your dog for heartworm. Monthly chewables, a yearly injection, and even topical treatments are all available for you to choose from. The topic has become somewhat like contraception for humans - do you want to take a pill, get a long lasting injection, or take your chances with nothing? Except please don't 'do nothing' for heartworm... heartworm is much more deadly than an accidental pregnancy...

But, which heartworm prevention method is the best? Is the yearly heartworm injection more effective than monthly chewables? Which is the best value, and most importantly - which is the safest?

The truth is, there is no 'one size fits all' best treatment. Different regimes work better for different households. As a guide, we've taken you through all options available, listed the pro's and cons, and outlined the general costs of each so you can make up your own mind.

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1. The yearly heartworm injection

2. Oral monthly prevention

3. Topical monthly prevention

4. Daily prevention

SUMMARY - a complete comparison table of all options


Shop Our Top Selling Heartworm Preventatives:

Not sure what heartworm actually is, or how the disease and prevention works? See our other article Everything you need to know about Heartworm.

Whichever heartworm prevention you choose, it's important you remember to give it on time. If your dog's prevention has lapsed and is more than 3 months overdue, you will need to test them for heartworm before giving it again. Likewise, if you adopt an adult dog with an unknown history of parasite prevention, you should test before treating. Giving heartworm prevention to a heartworm-positive dog can be deadly.


1. The yearly heartworm injection

Cost per year: depending on your vet clinic, anywhere from $60 (toy breeds) to $250 (giant breeds) per dog, per year.

Hidden costs: because the heartworm injection has no coverage for fleas, ticks, or intestinal worms, you will need to buy extra intestinal worming and flea and tick products throughout the year (anywhere from $100-250 per year, per dog). Depending on your vet, you may also need to pay for a consultation ($60-90) when you have the needle administered.

Facts: The yearly heartworm injection (Proheart SR12) is an annual needle that lasts for a full twelve months. In growing puppies, a couple of boosters are required (one at 12 weeks of age, another at 6 months, and then again around 12 months of age) but after this, the injection is yearly. The heartworm injection is only available for dogs; currently there is no injection for cats.

How does the yearly heartworm injection work? Many people refer to this injection as a 'heartworm vaccine'. However, technically it doesn't actually work like a vaccine. Vaccines work by exposing your dog's immune system to a small sample (killed or live) of an antigen, which causes the creation of antibodies; if the disease is then encountered in the future, your dog's body will know what to do. The heartworm injection, however, is not a vaccine. Instead, it uses microspheres which contain an anti-heartworm compound. (Yes - that liquid injected under your dog's skin actually contains thousands of microscopic balls! This is also why a large-gage needle is required, as the liquid is very thick.) Over time, the microspheres gradually dissolve and release their compoud, keeping your dog protected for 12 months. Technically this means that even anti-vaxxers should be fine with the heartworm injection, as it doesn't involve injecting antigen into your dog - instead it is more similar to implant technology.

Myths about the heartworm injection - keep in mind that the heartworm injection only covers for heartworm. Many pet owners get confused about the 'parasite injection' that 'covers for fleas and ticks too' - but this kind of thing doesn't exist. The only anti-parasite injection on the market for dogs is for heartworm only. You will still need to give extra products for intestinal worms and fleas.

What we recommend pairing it with: Drontal for intestinal worming, and Bravecto for flea and tick prevention. Drontal covers for intestinal worms, but has no heartworm coverage so you won't be doubling up with the injection. Both of these are given every 3 months, or once per season, which lines up conveniently.

Pros of the heartworm injection

  • Peace of mind knowing that your dog has heartworm protection for a full year (- ie good if you are forgetful!)
  • Generally 100% effective if injected correctly
  • No tableting required

Cons of the heartworm injection

  • Can be costly in larger dogs
  • Requires a visit to the vet and large-gage needle injection (can be stressful for some dogs)
  • Hidden costs are high - as there is no coverage for intestinal worms or fleas and ticks, so you will have to buy these on top (we recommend Drontal for intestinal worming, and Bravecto for flea and tick prevention.


2. An oral monthly heartworm product

Products in this category:

For the purpose of this comparison, we are only going to discuss the first two options. Combination products which include at least intestinal worms as well are always recommended over heartworm-only products, for your own convenience. If you select a heartworm-only monthly product, you will need to pair it with both an intestinal wormer like Drontal, as well as a flea product like Simparica. (Save yourself the hassle of having to give three separate products - go for a combination product from the start!)

Cost per year: depending on the product and the size of your dog, anywhere from $66-100 per year for a worm/heartworm-combination product, up to $114-200 per year for a complete worm/heartworm/flea/tick combination product per year.

Hidden costs: none, if you select a comprehensive product like Nexgard Spectra, as your parasite prevention will be complete (apart from the hydatid tapeworm).

However If you choose a worm/heartworm-combination product like Interceptor or Milbemax, you will need to buy another product for fleas (and ticks, if this is a risk in your area).

Facts: Monthly oral heartworm prevention usually contains a drug such as milbemicin or ivermectin, which belong to the macrocyclic lactone family (this is the same family of drugs used for oral prevention). Just like with oral prevention, the intention of monthly heartworm prevention is to kill any 'baby' heartworm larvae before they mature into adults. Due to the lifecycle of heartworm, monthly administration is sufficient to prevent this maturation stage from occurring.

What we recommend pairing it with: If you choose a monthly oral combination product like Nexgard Spectra, you shouldn't need to pair with any other products at all (unless your vet recommends a small tapewormer tablet such as Droncit).

However if you choose a worm-heartworm only combination product, we recommend pairing it with a monthly flea and tick preventative like Simparica or Nexgard (not to be confused with Nexgard Spectra). These are both monthly, which means all your preventatives will line up monthly.

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Pros of oral monthly heartworm prevention

  • Generally 100% effective if given on time
  • Tasty chewables available (no needle required!)
  • Combinations available for convenient all-in-one parasite prevention
  • Affordable long term, due to minimal (if any) extra purchases required

Cons of oral monthly heartworm prevention

  • Must be remembered on time - not ideal for forgetful dog owners
  • More frequent administration than a yearly injection
  • Difficult in fussy dogs who won't take worming chews

Best Oral Monthly Heartworm Products



3. A topical monthly heartworm product

Products in this category: Revolution (a topical flea / mite / heartworm combination) and Advocate (a topical flea / mite / heartworm / intestinal worm combination).

Cost: depending on the product and size of your dog, both Revolution and Advocate are approximately $150-195 per year, if the best value packs are purchased.

Hidden costs: You may need to buy an intestinal wormer and an extra product for tick prevention, if you live in a tick area.

Facts: Topical heartworm prevention usually contains a drug from the macrocyclic lactone family, such as selamectin or moxidectin. Macrocyclic lactones work similar to the oral preventatives, by killing baby heartworm larvae. The intention of monthly heartworm prevention is to kill any 'baby' heartworm larvae before they mature into adults. Due to the lifecycle of heartworm, giving monthly is sufficient to prevent this maturation stage from occurring.

What we recommend pairing it with: Advocate and Revolution cover for fleas, mites, and heartworm. Ticks and tapeworm are not covered - and while Advocate covers for intestinal worms, Revolution does not. If you are in a tick area - which includes the entire East Coast of Australia - we recommend pairing with a reliable tick preventative like Seresto, Bravecto, Simparica or Nexgard (not to be confused with Nexgard Spectra). With Revolution, we recommend also pairing with a broad spectrum wormer such as Drontal.

Pro's of topical monthly heartworm prevention

  • Generally 100% effective if given correctly and on time
  • Topical administration - great for fussy dogs who won't eat chews
  • Combinations available for fleas and worms

Cons of topical monthly heartworm prevention

  • Must be remembered on time - not ideal for forgetful dog owners
  • More frequent administration than a yearly injection
  • Hidden cost: You may need to purchase extra tick prevention depending on your area

Best Topical Heartworm Products



4. A daily heartworm tablet

Products in this category: This type of medication is mostly phased out these days, but Aristopet and Dimmitrol are both still available for daily administration.

Cost: $30 - $45 per year depending on your dog's size.

Hidden costs: You will need to purchase a separate product for fleas and ticks and another product for intestinal worming. It is also recommended that dogs treated with daily heartworm medication undergo a heartworm test every 6 months. This appointment will cost you between $100-350 per year depending on your vet's prices.

Facts: Once the only option available for heartworm prevention in dogs, daily medication was originally commonplace but is now mostly phased out. It has completely disappeared from overseas markets but is still available in Australia. Containing the drug diethylcarbamazine, these tablets need to be given daily; even missing just two days can put your dog at risk of contracting heartworm. (ie: monthly prevention is much more convenient and safe!)

What we recommend pairing it with: To be honest, we don't recommend daily heartworm medication at all, as there are so many monthly options available nowadays. But if you do choose to use a diethylcarbamazine-containing product, we suggest pairing it with Drontal for intestinal worming, and Bravecto for fleas and ticks. Both these medications are given every three months.

Pros of daily heartworm prevention

  • Affordable at face value (but other costs are involved... see below)

Cons of oral monthly heartworm prevention

  • Must be given every day - even two missed days can put your dog at risk.
  • Costly in the long run - as extra products need to be purchased for intestinal worming and fleas, and heartworm tests are required every 6 months.
  • Difficult in fussy dogs who won't take tablets

Still confused? See our table below for a complete summary.

Product Coverage Frequency Method Cost per year Hidden Costs Recommend to pair with
Yearly Heartworm Injection Heartworm Once per year Needle $60-250 Consult fee (in some clinics) + flea prevention + intestinal worming + tick prevention (in tick areas) Bravecto for fleas and ticks + Drontal for intestinal worming.

Nexgard Spectra

Ticks + fleas + mites + intestinal worms + heartworm Every month Tasty chew $165-200 None (or tapewormer if your vet recommends) None required (or Droncit for tapeworm if your vet recommends)

Sentinel

Fleas + intestinal worms + heartworm Every month Tasty chew $135-185 Tick prevention (for tick areas) Nexgard for ticks

Comfortis Plus

Fleas + intestinal worms + heartworm Every month Flavoured Tablet $134-174 Tick prevention (for tick areas) + tapewormer Nexgard for ticks, (Droncit for tapeworm if your vet recommends)

Interceptor

Intestinal worms + heartworm Every month Tasty chew $67-102 Flea prevention + tick prevention (for tick areas) Simparica for fleas and ticks

Milbemax

Intestinal worms + heartworm Every month Tablet $30-400* Flea prevention + tick prevention (for tick areas) Simparica for fleas and ticks

Advocate

Fleas + mites + intestinal worms + heartworm Every month Topical spot-on $142-200 Tick prevention (for tick areas) + tapeworm (if your vet recommends) Nexgard for ticks

Revolution

Fleas + mites + heartworm Every month Topical spot-on $150-182 Tick prevention (for tick areas) + intestinal worming + tapeworm (if your vet recommends) Drontal for intestinal worming + Nexgard for ticks

Dimmitrol

Heartworm Daily Tablet $30-45 Flea prevention + tick prevention (for tick areas) + intestinal worming + 6 monthly heartworm test at your vet Bravecto for fleas and ticks + Drontal for intestinal worming

Prices may vary - please check individual product links for current prices

What do our vets recommend?

After a straight-forward recommendation? We asked our in-house veterinarians what they personally recommend.

Dr Carla - for heartworm prevention, I usually recommend Nexgard Spectra. It has complete parasite coverage (apart from tapeworm), and most people find that once monthly dosing is easy to remember. If you are especially forgetful, it might be best to go for the yearly heartworm injection and use the Bravecto / Drontal combination for all your other parasites.

Dr Kim - For dogs, I personally recommend Nexgard Spectra. It's a monthly chewable that covers the four major parasites - paralysis ticks, fleas, heartworm and the most important intestinal worms. Just remember to give your dog a tapewormer about every 3 months for complete coverage.

Dr Teagan - I prefer the annual heart worm injection for most dogs as it offers effective coverage year long without owners having to remember monthly medication. I like to pair it with quarterly Drontal and Bravecto so that oral treatments are only needed 4 times a year!


Still not sure what is best? Why not ask our vets any questions you have and what they recommend for your pet.

Further Reading

New puppy guide

Premium pet food: Is it worth it?

Teach your puppy to walk on a lead

Boredom busters for dogs

Your guide to fleas, ticks and worms

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