The Best Heartworm Prevention for Dogs

Written by Opal
Updated: January 20, 2023
© iStock.com/Wild spirit shoot

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Key Points

  • The #1 Best Overall heartworm prevention for dogs is the Heartgard Plus Chew for Dogs.
  • It is extremely dangerous for dogs to have heartworm illness, which can be fatal. These infections can lead to dogs needing to be hospitalized and treated immediately. It is for this reason that proactive measures are so important with regard to heartworm prevention. 
  • Our research focused on finding the best heartworm prevention for dogs using top-rated picks and reviews. Several different factors were considered, including the type and cost of the medicine, as well as possible side effects.

Did you know that heartworm disease can be incredibly dangerous for dogs? In fact, when left untreated, it can be fatal. Heartworm disease can be prevented, however,  and we found the best heartworm prevention medicines available.

Heartworm is a parasite that may dwell in a dog’s or cat’s heart and pulmonary artery. The worms can grow up to one foot long and resemble very thin spaghetti noodles. By eating the tissue, they inflict harmful effects on the heart and vascular tissue. Heartworms can also obstruct the pulmonary artery, reducing blood supply to the heart and lungs and causing severe harm. 

In order to keep your dog healthy, you must administer heartworm medication regularly, regardless of the form in which it is administered. The most common types of supplements are oral and injectable. It is fairly common for these medications to contain similar ingredients. 

If you are trying to prevent heartworms, you may wonder why it is so important to do your research. Well, for starters, some of the ingredients in the medicine can interfere with other medications. Prescriptions for dogs come with potential side effects, just like prescriptions for humans. Having conducted extensive research, our team has identified the most reliable and trusted options. Our in-depth reviews and buyer’s guide will help you make an informed buying decision.

  1. Heartgard Plus Chew for Dogs
  2. Heartgard Plus Chew for Dogs
    • Popular choice of veterinarians
    • Safe for puppies over six weeks old
    • Delectable meat flavor
    • Reasonably priced
    Check Chewy
  3. Tri-Heart Plus Chewable Tablet for Dogs
  4. Tri-Heart Plus Chewable Tablet for Dogs
    • Effective against heartworm larvae
    • Great for smaller dogs as well as larger dogs
    • Side effects are rare
    • Budget-friendly option
    Check Chewy
  5. Advantage Multi Topical Solution for Dogs
  6. Advantage Multi Topical Solution for Dogs
    • Active for up to 30 days
    • Prevents heartworm, sarcoptic mange, hookworm, roundworm, and whipworm
    • Requires a veterinary prescription
    • The product box comes with either six or twelve dose options
    Check Chewy
  7. Sentry HC WormX Plus 7 Way Dewormer
  8. Sentry HC WormX Plus 7 Way Dewormer
    • Kills seven strains of hookworm, tapeworm, and ringworm
    • Active ingredients are pyrantel pamoate and praziquantel
    • Comes in a tasty chewable
    • Can be administered for prevention
    Check Chewy Check Amazon

Top Picks: The Best Heartworm Prevention for Dogs Today

#1. Best Overall: Heartgard Plus Chew for Dogs

As one of the most popular choices from veterinarians, the Heartgard Plus Chew for Dogs is also one of our favorites. These tasty beef-flavored chews are designed to prevent heartworms before they start. In addition, Heartgard controls roundworms and hookworms. 

Pet parents are expected to give dogs these chews once a month. While they are safe for puppies over six weeks old and pregnant dogs, collies tend to be sensitive to heartworm medications that have Ivermectin. It is possible for certain breeds of dogs, such as collies, to be allergic to this active ingredient. These chews are not recommended for such breeds. 

We also want to mention that there are side effects with Heartgard just like any other heartworm medication. The most common with beef-flavored chews is diarrhea and vomiting. Side effects usually occur within the first 24 hours of eating it. Please contact your vet if your pooch is experiencing these or any other side effects. 

Because of its proven effective mix and tasty meat flavor, Heartgard Plus Chew for Dogs is the best overall heartworm treatment for dogs. It’s also incredibly easy to give to your pup and is reasonably priced in comparison to its competitors.

Pros and Cons of the Heartgard Plus Chew for Dogs

ProsCons
With its tasty beefy flavor, the chew is easy to administer.Due to their sensitivity to Ivermectin, collies are not suitable for this medication.
In addition to preventing heartworms, it will also prevent roundworms and hookworms.
Suitable for puppies aged six weeks and older.
As it lasts up to 30 days, you only need to administer it once a month.
Overall Best
Heartgard Plus Chew for Dogs
  • Popular choice of veterinarians
  • Safe for puppies over six weeks old
  • Delectable meat flavor
  • Reasonably priced
Check Chewy

2. Best Budget: Tri-Heart Plus Chewable Tablet for Dogs

Consider the Tri-Heart Plus Chewable Tablet for Dogs if you’re looking for a budget-friendly option that will protect your pet. As pet parents, we all know how expensive it can be to keep your dog in good health. Thankfully, with Tri-Heart Plus Chewable Tablets you don’t have to skimp on your pooch’s health just to save a buck. 

The Tri-Heart chews are designed with an enjoyable formula that dogs love. It’s effective against heartworm larvae. Just like our top pick, this chew also helps control and treat hookworms and roundworms. 

These are great for smaller dogs because the chew comes in a small size that’s easy to consume. The delicious beef flavoring encourages canines to eat them with ease. Another great feature about this option is that side effects are rare, making this a great choice for dogs with sensitive tummies. 

Both Tri-Heart Plus and Heartgard Plus contain the active ingredient ivermectin, so if you own a border collie this is not the best option for them. Otherwise, if you’re looking for a medication that won’t break the bank, consider the Tri-Heart Plus chews!

Pros and Cons of the Tri-Heart Plus Chewable Tablet for Dogs

ProsCons
A cost-effective pet care option.Herding dogs such as collies are sensitive to ivermectin. Consult your veterinarian about alternative options.
It protects against three types of parasites: heartworms, roundworms, and hookworms.
The chewable tablet has a delicious taste and is easy to feed to your dog.
It is safe for dogs with sensitive stomachs since side effects are rare.
Best Budget
Tri-Heart Plus Chewable Tablet for Dogs
  • Effective against heartworm larvae
  • Great for smaller dogs as well as larger dogs
  • Side effects are rare
  • Budget-friendly option
Check Chewy

3. Best Longterm Injectable: Advantage Multi Topical Solution for Dogs

Try out the Advantage Multi Topical Solution for Dogs instead of chewable tablets if your pet won’t take them down.

Is your furry friend picky about what they’ll eat? Then you’ll love being able to topically apply their heartworm prevention medication topically. What makes Advantage Multi so great is that this medication treats adult fleas, hookworms, whipworms, roundworms, sarcoptic mange, and ear mites in cats and prevents heartworms. This product lasts for 30 days, which is the industry standard. However, you can still treat your cat or dog if you go over a couple of days.

Puppies can be treated with this medication as early as seven weeks of age. A great feature of this medication option is that it comes in a product box with either six or twelve doses. In addition, it begins to work within 24 hours. Having more than one pet, however, requires extra caution. You must separate your pets before giving them this medicine to prevent them from licking the treated area. It can be very dangerous for them to lick the treated areas. You should apply this to an area of your dog where they cannot lick it.

Pros and Cons of the Advantage Multi Topical Solution for Dogs

ProsCons
If your dog is picky about chewables, this is the perfect option for them.You need to separate your pets if you have multiple animals so that they don’t lick the medication.
The medication prevents heartworm as well as fleas, sarcoptic mange, roundworms, hookworms, and whipworms.
The product box comes with either six or twelve doses.
Best Longterm Injectable
Advantage Multi Topical Solution for Dogs
  • Active for up to 30 days
  • Prevents heartworm, sarcoptic mange, hookworm, roundworm, and whipworm
  • Requires a veterinary prescription
  • The product box comes with either six or twelve dose options
Check Chewy

4. Best for Medium to Large Dogs: Sentry HC WormX Plus 7 Way Dewormer

Dogs of medium to large sizes can safely be treated with Sentry HC WormX Plus 7 Way Dewormer. Sentry Pet Care offers an effective seven-way dewormer for dogs in the medium to large size range. The product kills seven strains of hookworms, tapeworms, and ringworms. 

It has two active ingredients, pyrantel pamoate, and praziquantel, that are found in expensive veterinary-specific brands. This specific option is designed for dogs that weigh more than 25 pounds, but Sentry does have a dewormer for smaller breeds as well. Though it is a dewormer, it can also be administered for prevention. Since there is no prescription requirement, everyone can access the medicine at any time and anywhere.

Like other options, we mentioned earlier, Sentry comes in a tasty chewable that your dog will enjoy. The chewable should be administered according to your pup’s weight and is effective for up to 30 days. However, it is important to note that some reviewers noted that it makes digestion difficult for their dogs. So if your dog has a sensitive stomach then this may not be the best option for them.

Pros and Cons of the Sentry HC WormX Plus 7 Way De-Wormer

ProsCons
It treats seven types of worms, including tapeworms, roundworms, and hookworms.For those with sensitive stomachs, this medicine can be harsh.
There is no need for a prescription, so the medicine is easily accessible when you might need it.
A perfect option for medium to large-sized dogs.
Best for Medium to Large Dogs
Sentry HC WormX Plus 7 Way Dewormer
  • Kills seven strains of hookworm, tapeworm, and ringworm
  • Active ingredients are pyrantel pamoate and praziquantel
  • Comes in a tasty chewable
  • Can be administered for prevention
Check Chewy Check Amazon

How to Choose the Best Heartworm Prevention for Dogs

Heartworm prevention is important for the health of your dog. Heartworms infest the heart and the vessels surrounding it in your dog. The most common means of spreading them between dogs is by mosquitoes. If heartworms get too big and numerous, they can stop the heart from pumping blood properly. There is a possibility of heart failure as a result. This is why it is so important to choose an effective and safe heartworm prevention option for your pup. If you’re still unsure about which heartworm treatment is right for your dog, we’ve got you covered.

There are three main factors you need to consider when choosing the best heartworm prevention for your pup:

  • Type of medicine 
  • Cost 
  • Side effects 

In the following sections, we will explore each of these factors in greater detail:

Type of Medicine

Combination heartworm treatments come in a variety of formats, including pills and topically applied solutions, for added convenience. A wide range of administration options makes it easier and more convenient to choose the best one for your pet.

If heartworm prophylaxis is applied topically to pets that don’t take pills well, they are more likely to cooperate. Chews come in delicious flavors that pets enjoy and will easily digest. While injections are the most convenient for pet owners, you need to be extra careful to make sure that they are not ingested by your pets.

Cost

Just like anything else with your furry friend, the cost can play a part. Not all heartworm medicines come at the same price point and this is something you’ll want to consider. There are many great options that do come at an affordable price.

Side Effects

Most dogs will not experience side effects from heartworm prevention medications. We are, however, mentioning it because it is not impossible, so you know what to expect. In the first 24 hours after taking the medication, diarrhea and vomiting are the most common side effects.

Active Ingredients in Heartworm Medication

Heartworm medications use several typical active compounds. Because dogs might have allergies or other sensitivities, it’s critical to be knowledgeable about these components. Some of these chemicals have potentially dangerous negative effects. You’ll almost certainly come across the following substances when looking for heartworm treatment for dogs.

Milbemycin Oxime

Milbemycin oxime is another common heartworm and other internal parasites preventative ingredient. It’s also frequently mixed with flea medicine to create a broad-spectrum dog treatment. This substance is often given to dogs orally. You can give it with or without food. If your dog has an upset stomach, try giving it some food to eat. Some medications and supplements may also be affected by milbemycin oxime.

Ivermectin

One of the most popular active components in heartworm treatment is ivermectin. It is also used to treat various parasites and vermin in the intestine. When given to your dogs in the right amounts, this substance seldom causes any negative effects. An unsettled stomach is the most typical adverse effect.  It’s vital to keep in mind that herding breeds, such as collies, might be sensitive to ivermectin owing to a genetic mutation. Be sure to talk to your vet if you have any concerns about the ingredients on this list.

Moxidectin

It is also possible to apply moxidectin externally in addition to taking it orally. This antiparasitic is used to treat intestinal parasites, mange, and heartworms. To treat fleas, it’s frequently used with imidacloprid. Check when you can safely wash your dog next without interfering with the medication if your dog has received topical treatment.

There are very few side effects. Moxidectin, on the other hand, can cause deadly symptoms in certain dogs with milbemycin sensitivity. As a result, it’s critical to get advice from a veterinarian before utilizing moxidectin. There aren’t any reports that moxidectin interferes with any drugs. If your dog is taking a benzodiazepine prescription, you should give it with caution.

Pyrantel

The majority of heartworm drugs aren’t only for heartworms. The use of dewormers is also common for treating other internal parasites. A common active component of ivermectin is pyrantel. In addition to treating roundworms, hookworms, and other kinds of stomach worms, it is also a dewormer.

Vomiting, nausea, loss of appetite, and constipation are some of the less typical side effects. Because vomiting can occur if you take this medication on an empty stomach, it’s best to take it with food. The elimination of parasites from the body can cause vomiting, diarrhea, and a loss of appetite.

Pyrantel is generally safe for pregnant or nursing dogs. However, you must administer the correct dosage. It is also possible that some canines are allergic to it. It interacts with levamisole, morantel, piperazine, and organophosphates, among other medications.

The 2 Different Types of Heartworm Prevention for Dogs

You now know that there are two main types of heartworm prevention medications available for our four-legged friends. Taking a look at these two options, let’s compare their pros and cons.

  • Chewable tablets — This option is easy to consume and often comes in a flavor that dogs enjoy. They can be administered at home. However, dogs who are picky about what they’ll eat may refuse to consume them.
  • Injectable — This option is great for dogs who are picky eaters or who have sensitive stomachs. You must be careful to make sure that the medication is not ingested by your dog or other pets.

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About the Author

When she's not busy playing with her several guinea pigs or her cat Finlay Kirstin is writing articles to help other pet owners. She's also a REALTOR® in the Twin Cities and is passionate about social justice. There's nothing that beats a rainy day with a warm cup of tea and Frank Sinatra on vinyl for this millennial.

The Best Heartworm Prevention for Dogs FAQs (Frequently Asked Questions) 

Is heartworm treatment really necessary for dogs?

One of the most frequent questions that veterinarians hear during an annual wellness visit has to do with heartworm medication. Simply said, the answer is yes! All cats and dogs, even if they are deemed as indoors-only pets, should be on heartworm preventive medicine.

How frequently do dogs need to be treated for heartworm?

Considering heartworms must be eradicated before they mature into adults, it is critical that heartworm preventives are used on a regular basis. This is often monthly for oral and topical medications.

Is it possible for a dog to go without heartworm medication for an extended period of time? 

If a dosage is missed, most monthly heartworm treatments provide a safety margin of around 15 days of protection. This implies that even if you’re just a week or two late, your pet is most likely still protected and unlikely to become sick at that period.

What happens if your dog is given two heartworm tablets in a month? 

There is no need to be concerned if it was Heartgard. It’s a fairly safe substance that’s tough to overdose on. If it was something like ivermectin formulation, a double dosage might not be a problem unless your dog is allergic to it or has the MDR1 gene. In either instance, please reach out to your veterinarian.

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