Heartgard Plus Chewable Tablets for Dogs, 51-100 lbs, 6 treatments

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Heartgard Plus is a heartworm preventative that kills heartworms and helps to control and treat hookworms for dogs 51 to 100 lbs. Given monthly, it comes in a chewable tablet that you can feed to your pal as a tasty, beef-flavored treat. Head back to the dog park, reassured that your dog is protected from nasty parasites.


To prevent heartworm disease by eliminating the tissue stage of heartworm larvae (Dirofilaria immitis) for one month (30 days) after infection.

Possible Side Effects

Please contact your veterinarian if your pet is suffering from the following: depression/lethargy, vomiting, anorexia, diarrhea, mydriasis, ataxia, staggering, convulsions, and hypersalivation.

Drug & Food Interactions

Heartgard Plus has shown a wide margin of safety at the recommended dose level, including pregnant or breeding females, male dogs and puppies aged six or more weeks. In clinical trials, many commonly used flea collars, dips, shampoos, anthelmintics (anti-parasitic drugs), antibiotics, vaccines and steroid preparations have been administered with this medication in a heartworm disease preventive program.


All pets should be tested for existing heartworm infection before starting treatment with this medication, which is not effective against adult heartworm. Keep this and all drugs out of the reach of children. In case of ingestion by humans, clients should be advised to contact a physician immediately. Physicians may contact a Poison Control Center for advice concerning cases of ingestion by humans.

  1. Prescribing Information

See all items by Heartgard

  • Item Number
  • Common Brand Name(s)

    Heartgard Plus, Tri-Heart Plus

  • Dosage Measure

    Use according to your veterinarian's instructions.

  • For Use With

    Dogs - 6 weeks or older

  • Generic Name

    Ivermectin, Pyrantel Pamoate

  • Brand

    Merial, Boehringer Ingelheim

  • Breed Size

    Medium Breeds, Large Breeds

  • Product Form

    Chewable Tablet

  • Health Condition

    Heartworms, Roundworms, Hookworms

  • Drug Type




Recommended Dosage

This medication should be administered orally at monthly intervals. Consult your veterinarian for proper dosing instructions.

Storage Instructions

Store between 68° - 77°F. Protect product from light.

Dosing Chart

Heartgard Chewables should be administered orally at monthly intervals at the recommended minimum dose level of 6.0 mcg of ivermectin per kilogram (2.72 mcg/lb) of body weight. The recommended dosage schedule for prevention of canine heartworm disease is as follows:

Dog Weight HEARTGARD for Dog per Month Ivermectin content Color Coding on Foil Backing and Carton
Up to 25 lbs 1 chewable 68 mcg Blue
26 to 50 lbs 1 chewable 136 mcg Green
51 to 100 lbs 1 chewable 272 mcg Brown

Give dogs over 100 lbs the appropriate combination of these chewables. HEARTGARD Chewables are recommended for use in dogs 6 weeks of age and older.


What is heartworm disease?

Heartworm disease in dogs (dirofilariasis) is a serious and potentially fatal disease. Heartworms spend their adult lives in the pulmonary arteries. The adult worms can cause lasting damage to the heart, lungs and arteries.

How do dogs get heartworms?

Heartworms are transmitted from one dog to another by mosquitoes, which pick up tiny immature heartworms, called microfilariae, when they bite an infected dog. Larvae develop and are then transmitted to another dog when that dog is bitten by the infected mosquito.

Where are dogs at risk for heartworm infection?

All dogs are at risk for heartworm disease, no matter where they live—heartworms don't discriminate based on geography. In the past, heartworm disease in the United States was primarily limited to the South and Southeast regions. However, it is now found in all 50 states, in Canada, and is spreading to new areas each year. The American Heartworm Society notes that uncared-for dogs and certain wildlife can be carriers of heartworms. Mosquitoes blown great distances by the wind and the transportation of infected pets to different geographic locations can all contribute to the spread of heartworm disease.

What are the signs of heartworm infection?

Signs of heartworm disease can be subtle and difficult to detect until its later stages. As the disease progresses, signs begin to appear. Contact your veterinarian immediately if you notice coughing, difficulty breathing, sluggishness and less energy for exercise in your dog. Adult heartworms cause serious harm to your dog's heart, lungs and certain internal organs. Left untreated, heartworm disease can result in loss of consciousness and death.

How are dogs tested for heartworm infection?

The most common method for heartworm testing is for a veterinarian to collect a small blood sample from a dog and evaluate the sample using a specialized test kit to detect the presence of adult heartworms.

How can heartworm disease in dogs be prevented?

Pet owners can use Heartgard Plus (ivermectin/pyrantel), the #1 veterinarian-recommended preventive on the market to help prevent heartworm disease. Heartgard Plus kills tissue larval stages of heartworms and helps prevent them from developing into adults and causing heartworm disease. In an unprotected dog, heartworm larvae mature into adults and ultimately migrate to the arteries of the lungs.

How long do I have to give my dog Heartgard Plus?

Monthly use of Heartgard Plus is essential because it cannot be determined with certainty when the threat of mosquitoes has passed. Talk to your veterinarian for dose and regimen recommendations.

Can heartworm disease be treated?

Although it is possible to treat heartworm disease if a dog becomes infected, it is difficult, expensive and risky, particularly in dogs that have begun to exhibit clinical signs of infection.

What if my dog becomes infected with heartworms?

There are treatment options available to kill adult heartworms in dogs that have become infected. Treating dogs with heartworm disease starts with a thorough physical examination by the veterinarian. The veterinarian will then discuss treatment options with you. Typically, the dog is hospitalized during the treatment period. Because there is a risk of blood clots or worm debris blocking blood vessels from adult heartworm treatment, the dog must then remain quiet in close confinement for another 4 to 6 weeks after treatment. A second round of treatment may be required for some dogs. The veterinarian may also give your dog a treatment to rid it of the immature larvae that are circulating through the blood stream.

Is Heartgard Plus safe to use in any breed of dog?

Heartgard Plus is safe and effective in any breed of dog when used as directed.

Can my dog "get" heartworm disease directly from an infected dog?

No, the way dogs become infected is via a bite from a mosquito that is carrying heartworm larvae.

Are nursing puppies immune to heartworm disease if the mother is receiving Heartgard Plus?

No. Puppies that are nursing may become infected. Heartgard Plus can be used in puppies as young as 6 weeks of age—and puppies benefit from the ability of Heartgard Plus to treat and control roundworms and hookworms.

Customer Reviews
42 Reviews 42 Reviews 4.9 out of 5 Stars

98% Recommend

98% of reviewersrecommend this product

4.9 / 5

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  • Heartgard Feedback

    By on

    We have been using this product for several years. We have never experienced any side effects and both of our dogs are extremely healthy. We did save quite a bit of dollars from the difference in price from our vet to the pricing of the same product from Chewy. We do sincerely THANK YOU Chewy!!!

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  • Price and Rebate

    By on

    Because I use Chewy for prescription dog food auto delivery I decided to try them for Heart Worm and Flea and Tick Preventative. When I bought it elsewhere I paid approx. the same amount but bought without a prescription (one was required by Chewy)and received a rebate which I did not receive from Chewy.

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  • Very Easy to Order

    By on

    This is the first time I have ordered a Veterinary prescribed item on line. The whole process was painless. I ordered on line because it was $26.00 less from Chewy than my vet. That's a significant savings. Chewy contacted my vet and everything went very smoothly. Thanks Chewy

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  • Heartworm Meds

    By on

    My Dog has been on this medicine for years. The is the first time I ordered from Chewy, they contacted my vet for me and then shipped the order. I had to pay shipping cost but the meds were still about $10.00 cheaper than my vet's.

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  • Heartguard

    By on

    At first I didn't realize they had to get hold of my vet. They did but it was my vets doctor that drug his feet. As soon as he responded you filled my order & it was on it's way..Thank you !! She's (Jinxy) now set for the next 6 months.

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  • Heartgard Love!

    By on

    Thank you so much - Bailey loves her Chewy orders! We appreciate the prices and quick delivery! When Bailey became family over 5 years ago she had heartworm and was very sick. We always make sure she has her Heartgard! We get everything from here! Thank you! Bailey's mom and dad

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  • Heartguard Plus

    By on

    This product has the potential to save your dog suffering and the cost for treating heartworm is very expensive. I love that Chewy contacts my vet right away and the product is at my door less than 10 days later!

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  • My dogs think they're treats

    By on Top 50 Contributor

    My dogs love these chews. They start drooling when I open the package because they think they're getting a treat. Super easy to administer and chewy has the best price I can find.

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  • Tried and True

    By on

    Heartguard is the only product we would consider using on our dogs. They seem to enjoy the taste and in four dogs over twenty seven years we have never had one get heartworms.

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  • Great Recommendation from Vet

    By on

    Have been using heartgard since having our two boys since they were pups and able to use heartgard. Recommended by our veterinarian and it has done what it is suppose to do ad we have had a clean bill of health.

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