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Top 4 Best Heartworm Medicines for Dogs (2020 Review)

Looking for the best dog medicines and heart worm prevention for your dog?

You're in the right place! 🙂

In this guide you'll learn:

  • What heartworms are and how most dogs get them in the first place
  • How the process of treating heartworms works
  • What to expect during the whole process
  • Our top 4 recommended products for your dog
best dog heartworm prevention and medicine

Let's get into the guide!

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4 Best Heartworm Medicines For Dogs

Short on time?  Take a look below for the top 4 in our list. Otherwise, check out our buying guide and learn how to defend your dogs from heartworms!

​Dogs are indeed a man's best friend. In fact, most of us consider these adorable pets of ours as actual members of our families. They are naturally close to our hearts and it's only fitting that we take good care of theirs.

Whether we like it or not, dogs can be hosts to a wide variety of parasitic worms. Some don't pose a serious threat the pet's health but most of them are quite dangerous especially if left untreated such as the notorious heartworms.

​Once a dog is diagnosed with heartworm infection, the veterinarian would recommend a series of treatment procedures. In more serious cases, the whole treatment process can last for several months and can be quite costly. For pet owners, the most practical solution for such a problem would be prevention.

Read on to learn effective solutions to help your canine friends avoid getting infected with heartworm parasites.

What are dog heartworms?

Judging by its name, it seems pretty easy to understand what the disease is all about. A dog suffers from heartworm once it gets infected by a specific type of parasitic - Dirofilaria immitis. The heartworm disease has been known as the silent killer among dogs.


This is simply because symptoms of the said disease maybe observed only after the worm Dirofilaria immitis has reached maturity which is roughly around five to six months.

The heartworm is a foot-long nematode that resides inside the pet's significant blood vessels, especially the heart. If untreated, the disease may lead to lung infection, heart failure, and other cardiovascular complications. 

Surprisingly, all nematodes aren't bad. Checkout this guide where we review nematodes and how they can actually help you with other pests.

About The Infection

​Dog lovers and pet owners alike, especially those with minimal knowledge about heartworms may have a huge question as to how their best friends get infected by Dirofilaria immitis.

There is only one known and confirmed way dogs get the disease. And that is through the bite of an infected mosquito. If a mosquito sucks blood from a cat or dog suffering from heartworm disease, offsprings of Dirofilaria immitis get carried by the insect. It only takes two weeks or less for these microscopic younglings to develop into its larval stage. ​And when that same infected mosquito gets to feed again from its new victim, the larvae gets to enter into the bloodstream through the open wound of the mosquito bite.

It takes only about six to seven months for the larvae to reach full maturity. These nematodes can grow to about a foot in length and can linger around your dog's heart and lungs for up to seven long years. Serious cases of heartworm disease can yield to as much as 250 worms.

What Are The Symptoms For Heartworm?

​In most cases, heartworm disease infection goes undetected. In fact, it's quite challenging to detect the disease in its early stage because the victim will show minimal or no symptoms at all. It is very critical for the disease to be discovered as soon as possible to avoid the development of serious complications. Common symptoms of heartworm disease among dogs are dry stubborn cough, fatigue or fainting even on mild exercises, tardiness, weight loss due to loss of appetite, rapid heavy breathing, and swollen chest or abdomen because of fluid build-up as a direct manifestation of the infection.

What Happens If Heart Worm Goes Untreated?

​If left undetected and untreated, adult female heartworms continuously give birth to new baby nematodes. With an average lifespan of 7 years, more and more heartworms accumulate in various blood vessels of the infected dog. In most cases, these worms crowd the lungs which will result to your pet's labored breathing. Because of this, the lungs become ineffective in sufficiently oxygenating the blood which will leave a significant damage on the canine's vital organs - heart, brain, and liver. Furthermore, heartworms crowd the heart organ resulting to the so called caval syndrome or cardiovascular collapse which will require immediate surgical treatment.

mosquitoes cause heartworm in dogs

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How to fight heartworm disease? 

Just the same with other types of diseases, overcoming the nasty heartworm infection requires a three-tier solution: prevention, detection, and treatment/medication. 

What Can You Do To Prevent Heartworm?

Prevention has always been better than cure especially in the case of a heartworm infection. As discussed earlier, this disease can lead to serious complications that require months long treatment and medication. So instead of having your canine friend go through the painstaking process of medication, it's a whole lot better to consider precautionary measures.

Your pet's first line of defense will be comprised of prescription oral pills. This can be administered either monthly or once every six months depending on the type and formulation of your preferred preventive. This medication works by killing heartworms in their larval stage thus, preventing the nematodes from ever reaching its full adult and breeding phase. And considering that heartworm infection happens through mosquito bites, it is also imperative to use repellents that can effectively diminish your pet's risk to mosquito exposure.

What Can You Do To Detect Heartworm?

Considering the symptoms mentioned above, you may think that detecting a heartworm infection is quite easy. But detecting the said infection requires more than just the changes in the behaviour and physical appearance of your pet. One sure way of doing so is through regular visits to your local vet for a blood test. This way, the doctor can make accurate diagnosis and treatment recommendations if your pet dog is indeed infected by heartworms. If you don't have a local veterinary clinic or hospital nearby, you can simply buy DIY blood test kits wherein you can conveniently collect a sample from your canine and send it to a particular laboratory for interpretations. 

What Medication is There?

Medication is the most challenging part of fighting the infection. Basically, there are two types of treatment options depending on the severity of the case. The first type is through intravenous administration of trypanocidal agent melarsomine. This drug is intended to kill adult worms. A second set of medicine is then given to kill young heartworms. Lastly, an antibiotic is administered for the infection. In more severe situations, the vet may recommend immediate surgical operations to physically and directly remove all heartworms from the system of the dog.

Pro Tip - Defend You (and Your Pets) From Mosquitoes  

Mosquitoes are one of the main reasons dogs get heartworm. We recommend checking out our mosquito elimination guides to help defend you, your family, and your pets from mosquitoes.

What can you expect during and after treatment?

The entire duration of heartworm treatment for dogs can last around 5 to 7 months. During this period, it is crucial to strictly impose exercise restriction on the dog.


The first type of medication that will be provided is intended to kill the adult heartworms. When these nematodes die, they disintegrate inside the system of your canine pet. Exercise restriction and keeping your pet quiet can help prevent blockage along the pulmonary vessels. A number of dogs have already died especially after treatment simply because their owners didn't impose exercise restriction on their pets.

Make Sure To Provide Monthly Preventative Care

​Monthly preventatives are a critical component in the entire maintainance  for dogs to avoid heartworm infestation. Compared to the actual medication in treating the disease, these preventatives are a measly 3% to 5%. And since most of the time, heartworm medication can reach around a thousand dollars, some pet owners opt to preventatives. However, monthly preventatives are only effective in killing off young heartworms. The adult ones linger and continue doing severe and permanent damage on the organs of the dog.   

After treatment, it is important to continue providing monthly preventatives to your dog. Even if your pet has just been treated from heartworm disease, there is still a big chance for the said disease to be contracted again. It is essential for every responsible pet owner to observe various precautionary measures all the time and this includes the monthly oral preventatives and various topical solutions.

Our Top 4 Recommendations 

In the below section we break down each of our product recommendations in a little more detail.​

​As their name implies, heartworms attack the heart of your pet. Nutrition Strength can help keep your canine's heart health at optimum condition through its cardio support supplement.

It's formulated to be 100% natural without any trace of harmful additives. It can be used on all breeds and sizes of pet dogs. Each tablet offers L-carnitine, L-taurine, Coenzyme Q-10, Selenimu, Magnesium, and Vitamin E to enhance heart muscle development and improve its overall health and functions.


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    ​All natural formulation
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    ​Tasty chewable tablets
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    120 tablets per bottle


  • ​May require quite some time to observe significant improvement
  • ​Some dogs may dislike the flavor/taste
  • Can be quite expensive for large dogs

Prevention is always better than cure. And since you already know by now that mosquitoes are the only vectors of the nasty heartworm disease, it is important to keep these notorious blood suckers away from your beloved pet at all times.

K9 Advantix II is an effective repellant against mosquitoes, ticks, and fleas. It is a contact type solutions and can work in as fast as ten minutes upon application. It is specially formulated to be waterproof so it works just the same even when your dog gets wet.

Click here to learn more specifically about dog tick medicines.


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    ​Fast action
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    Contact type: no biting needed


  • ​Itchy in the first few weeks
  • Can make pets quite lazy in the first few days
  • Can make your dog quite sick in the first hours of application

Our canine friends could also use some protection against mosquitoes especially now that we know that it only takes a single mosquito bite for dogs to get infected with heartworm.

A little spraying here and there from Pet Pleasant Pet Spray could just be the perfect tool to jump start your dog's day. It's a deodorizer and insect repellent in one convenient spray bottle. It is specially formulated to be safe for use on all pets and comes with pleasant citronella scent. 


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    2-in-1 insect repellent and grooming spray
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    ​Fresh citronella scent
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    ​All natural essentials for safety


  • Ineffective on heavy sand flea population
  • ​Sprayer gets easily jammed
  • ​Not so effective against mites

There's probably no better way to stop heartworm than to prevent it through the user of supplements.

One such supplement is milk thistle.

Safebay for Canines provides kidney and liver support as well as a detox specially formulated for all our canine friends.

It's formulated to remove damaging free radicals from your pet helping improve your dogs health.


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    Natural detox
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    ​Single pressed high potency formulation
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    ​Made strictly of high quality herbs


  • Not specifically for heartworm issues

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Our Top Pick: Nutrition Strength Cardio Support

Like us, our dogs also need their hearts well taken care of. Heartworms are very nasty parasites and are quite stubborn as well.

With the list above, I'd most recommend Nutrition Strength Cardio Support Plus Antioxidants for Dogs. Each tablet is packed with all the needed vitamins and minerals to keep your dog's heart healthy.

They also offer one full year money back guarantee which means that they are downright confident on the supplement's effectiveness. It's made of all natural ingredients so it's safe to use.

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2 thoughts on “Top 4 Best Heartworm Medicines for Dogs (2020 Review)”

  1. Maybe I am missing something here…. Your article says the nematodes you’re referring to are round worms. I thought that was odd as I have had to “worm” my dogs in the past and I am pretty sure it was round worms–so I looked it up; here is what I found:
    The adult roundworms live in the dog’s intestines. Their eggs are shed in the
    dog’s stool and develop into larvae. The life-cycle is repeated. Symptoms of
    roundworm infection include diarrhea, vomiting, pot-bellied appearance,
    coughing (dogs may cough up or vomit worms), weight loss and dull hair coat.
    from (link removed)

    Needless to say I am CONFUSED!

    • Hey Debi!

      You are right, we should not have referenced “round worm” in the article as it is confusing and we have removed it.

      Dog heartworms are not roundworms per se, they are a type of nematode as mentioned above.

      In general the term, “round worm” is used interchangeably quite a bit as a label for many types of worms.

      Hopefully this cleared up the confusion!


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