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Heartgard vs. Heartgard Plus: What Are the Differences?

Written by: Brooke Billingsley

Last Updated on June 26, 2024 by Dogster Team

Heartgard vs Heartgard Plus featured image

Heartgard vs. Heartgard Plus: What Are the Differences?


Dr. Chyrle Bonk Photo


Dr. Chyrle Bonk

DVM (Veterinarian)

The information is current and up-to-date in accordance with the latest veterinarian research.

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Review Summary

Heartworm is a deadly parasite that can impact dogs just about anywhere in the United States. They are most prevalent in the Southeastern US, but anywhere that has mosquitoes has the potential for heartworm disease. These parasites invade the heart and the vessels of the heart and lungs, potentially leading to permanent damage, heart failure, blood clots, and death.

Keeping your dog on regular heartworm prevention prescriptions from your vet is the best way to protect your dog against these awful parasites. Heartgard and Heartgard Plus are two of the most popular heartworm products on the market, but what’s the difference between them?

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At a Glance

Let’s look at the key points of each product.

  • Ivermectin is the active ingredient
  • Protects against heartworm
  • Safe for dogs 6 weeks and older
  • Kills heartworm in the larval stage
  • Discontinued
Heartgard Plus
  • Ivermectin and pyrantel are the active ingredients
  • Protects against heartworm, roundworm and hookworm
  • Safe for dogs 6 weeks and older
  • Kills heartworm in the larval stage and paralyzes hookworms and roundworms
  • More commonly used

Overview of Heartgard

Heartgard is a heartworm prevention medication with ivermectin as the primary ingredient. Ivermectin is capable of killing heartworms in their larval stage, preventing them from growing to adulthood in the blood vessels. Heartworms are spread through the bite of mosquitoes, which leave larva (microfilaria) behind in your dog’s blood after the bite. Without passing through a mosquito, a heartworm cannot complete its life cycle.

This medication is safe for dogs 6 weeks of age and older, although you should talk to your vet before giving Heartgard to a pregnant dog. It’s necessary to administer this medication as directed every 30 days. Late administration of Heartgard can allow your dog to be unprotected against heartworms. Once the worms pass their larval stage, Heartgard can no longer protect them.

Keep in mind that regular Heartgard has recently been discontinued, although some sites still have minimal inventory for sale. Your vet will only be offering Heartgard Plus. Unfortunately, we couldn’t find an exact statement from the company as to why they made the change, but we trust it was for good reason and that they’re now offering the best product to pet parents that they can.

  • Prevents heartworm larva from maturing
  • Safe for dogs 6 weeks and older
  • Slightly less expensive than Heartgard Plus
  • Does not kill heartworms past the larval stage
  • Must be administered every 30 days
  • Has been discontinued

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Overview of Heartgard Plus

Heartgard Plus Chew for Dogs

Like Heartgard, Heartgard Plus uses ivermectin as its primary ingredient to protect against heartworm. However, Heartworm Plus also contains pyrantel, which is an antiparasitic medication that is effective against roundworms and hookworms. Roundworms and hookworms are both transmissible to humans. They are transmitted through contact with infected feces or ground or grass where infected feces has been. By administering Heartgard Plus every month, you will protect your dog against heartworms, hookworms, and roundworms.

Heartgard Plus is also safe for dogs aged 6 weeks and over, but the same considerations should be made for pregnant bitches as Heartgard. This medication must be administered every 30 days for maximum heartworm protection. Hookworms and roundworms are much easier to treat and are overall less dangerous than heartworms.

  • Prevents heartworm larva from maturing
  • Protects against hookworms and roundworms
  • Safe for dogs 6 weeks and older
  • Does not kill heartworms past the larval stage
  • Must be administered every 30 days

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What Are the Differences Between Them?

Efficacy Against Heartworms

Edge: Tie

Heartgard and Heartgard Plus use the same doses of ivermectin to protect against heartworms. They are equal in their functionality for killing heartworms in the larval stage.

heartworm removed from dog
Image Credit: vitrolphoto, Shutterstock

Efficacy Against Intestinal Parasites

Edge: Heartgard Plus

Out of the two, only Heartgard Plus contains pyrantel, a medication that kills hookworms and roundworms. Because of this, only Heartgard Plus protects against these intestinal parasites.

Availability and Price

Edge: Heartgard Plus

While there is a rare handful of sites still carrying leftover stock of Heartgard, it has been discontinued, so Heartgard Plus is what you’re most likely to find available and what your vet would prescribe and recommend.

Ease of Use

Edge: Tie

These medications both come in a flavored chewable that most dogs find appetizing and will eat without fuss. Although they’re both extremely easy to administer for most dogs, these medications must be given every 30 days. If given late, then there is an increased risk for your dog to get heartworms.

person feeding poodle pet dog with preventive heart worms chewable
Image Credit: ThamKC, Shutterstock

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What the Users Say

We’ve gone ahead and done research to see what other dog owners have to say about using Heartgard and Heartgard Plus.

With Heartgard, they loved the simplicity of the medication and the efficacy against heartworms. For Heartgard Plus, dog owners love the fact that this medication protects against heartworms and some intestinal parasites. Since Heartgard is now discontinued, Heartgard Plus is easier to find in pet pharmacies and vet clinics.

Some people note that counterfeit products have ended up on the market, especially with unscrupulous online pharmacies. To keep your dog safe, it’s best to purchase these medications directly from your veterinarian, and that means you’ll be purchasing Heartgard Plus.

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When it comes down to it, Heartgard Plus is a better option than Heartgard. It provides greater protection for your dog against parasites, and since hookworms and roundworms can be contagious to humans, it also helps protect you and your family. Of course, regular Heartgard is no longer available since it has been discontinued, so you’ll have to purchase Heartgard Plus from your vet if you’ve always used and trusted this brand, although your vet will be able to provide you with all the options available to you.

Related Read: 

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