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Dog Heartgard Chewables

Rx Info
1. We'll ask for your vet's info during checkout.
2. We verify your prescription and ship your order!
Starts $44.99 $32.29 
Ships in one business day or less
Select Pet's Weight:
01-25 lbs
26-50 lbs
51-100 lbs
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6 pack
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Starts $44.99 $32.29 
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Product Info
How to Use
Customer Reviews
Product Info
What is Dog Heartgard Chewables?

Heartgard Chewables are a flavored treatment for dogs given once a month to prevent heartworms. Heartgard Chewables require a prescription from your veterinarian.

Looking to also control and treat roundworms and hookworms? Use Heartgard Plus Chewables.


Dogs (6 weeks of age or older and no weight requirement)

  • Highly effective in preventing heartworms
  • A convenient and tasty chewable for easy administration
  • Mess-free Smart Shield applicator simplifies application
  • Delicious beef flavor that most dogs will eat
How It Works:

Heartgard prevents heartworm disease by eliminating the tissue stage of heartworm larvae for a month after infection.

Studies have indicated that certain dogs of the herding breeds are more sensitive to the effects of ivermectin administered at elevated dose levels due to the MDR1 gene. For a full list of dog breeds that may be affected, click here.


Can cause sensitivities in herding dog breeds. It is important that you give your pet this preventative every month. If you miss more than two monthly doses, we recommend calling your vet before continuing the medication. Also, note that side effects are rare at the recommended heartworm prevention dose. Higher doses in dogs may cause tremors, dilated pupils, loss of body weight, and death. Side effects in cats include agitation, loss of appetite, staggering, dilated pupils, tremors, blindness and disorientation.

Brand Name:

Heartgard Chewable (Merial)

Generic Name:


What is the most important information I should know about Heartgard Chewables:

Heartgard Chewable is a prescription medication available for dogs as beef flavored chewable tablets. The usual dose of Heartgard Chewable for dogs up to 25 pounds is 68mcg (blue box), for dogs 26-50 pounds is 136mcg (green box) and for dogs 51-100 pounds is 272mcg (brown box). The chewable tablets must be chewed and should not be swallowed whole. For dogs that normally swallow whole, the chewable tablets can be broken into pieces.

What is Heartgard Chewables:

Heartgard chewable is given once a month for the prevention of heartworm disease in dogs. It is recommended by the American Heartworm Society that heartworm prevention be used year round. Heartgard may also be used for purposes other than those listed in this guide.

What should I discuss with my veterinarian before giving Heartgard to my pet:

Tell your veterinarian if your pet has ever had an allergic reaction to Heartgard, ivermectin, or to beef.

How should this medication be given:

Give Heartgard exactly as directed by the veterinarian. If you do not understand the directions ask the pharmacist or veterinarian to explain them to you. Heartgard chewable tablets must be chewed. They should not be swallowed whole. Use with caution, Collies and other herding dog breeds have been known to have adverse reactions to ivermectin administered at elevated dose levels. Heartworm testing should be performed prior to the start of prevention therapy. If the animal is off Heartgard Chewables for 6 months or less, start the medication and test after 6 months since microfilaria, that take 6 months to mature, will result in a positive test result. Store Heartgard chewable at room temperature. Do not remove the chew from its wrapper until ready to give the medicine. Keep this medication away from children and pets. In addition, Dog Heartgard Chewables has shown a wide margin of safety at the recommended dose level in dogs including pregnant or breeding bitches, stud dogs and puppies aged 6 or more weeks.

What happens if I miss giving a dose:

Give the missed dose as soon as you remember. Do not give a double dose of the medication.

What happens if I overdose the pet:

Seek emergency veterinary medical treatment. Symptoms of overdose may include vomiting, diarrhea and lack of coordination in dogs.

What should I avoid while giving Heartgard to my pet:

To help with compliance and not missing a monthly dose, use the handy red heart reminder stickers included with the medication.

What are the possible side effects of Heartgard:

Side effects of Heartgard are rare at the recommended heartworm prevention dose. Higher doses in dogs may cause tremors, dilated pupils, and loss of body weight and death.

What other drugs will affect Heartgard:

Do not give Heartgard to your pet if already taking another heartworm medication.

Where can I get more information:

Your pharmacist has additional information about Heartgard written for health professionals that you may read.

How to Use
  • Dog Heartgard Chewables are a once-a-month chewable tablet available by prescription for the prevention of heartworm disease in dogs.
  • It is recommended by the American Heartworm Society that heartworm prevention be given year-round.

Do not remove the chew from its wrapper until ready to give. Dog Heartgard Chewables must be chewed. They should not be swallowed whole. For dogs that normally swallow whole, the chewable tablet can be broken into pieces. Do not give a double dose of the medication.

Dogs Up to 25 lbs
Give 1 chewable tablet (68mcg-blue box) once a month
26-50 lbs
Give 1 chewable tablet (136mcg-green box) once a month
51-100 lbs
Give 1 chewable tablet (272mcg-brown box) once a month
Over 100 lbs
Give the appropriate combination of chewable tablets once a month
Do not use!
Do not use!

Store this product at room temperature. Keep out of reach of children.

Heartgard Blue Chewables (for Dogs 1-25 lbs):
Active Ingredient (per tablet)
68 mcg
Heartgard Green Chewables (for Dogs 26-50 lbs):
Active Ingredient (per tablet)
136 mcg
Heartgard Brown Chewables (for Dogs 51-100 lbs):
Active Ingredient (per tablet)
272 mcg
Customer Reviews
Dog Heartgard Chewables is rated 4.8 out of 5 by 96.
Rated 5 out of 5 by from Slow-kill for heart worms. We had a German Shepherd wander onto our property about a year ago who was starving and showed clear signs of abuse. He was petrified of everything and would melt into the floor with any movement or sound, loud or not. After working with him for a few months, we were finally able to get a vet to check him out. Unfortunately, he tested positive for heart worms. He was too unhealthy to use the fast-kill method of injections, (but I would never put an animal through that horrible treatment anyway), so my vet suggested the slow-kill method of a very specific antibiotic, steroids and Heartgard (brand only). You do that for one month, then just use the Heartgard once per month, like usual. He was a strong Stage 3 out of four a year ago and now he's a weak positive (Stage 1). Vet said this could take several years, which is better for the dog - especially if they aren't healthy to begin with. The worms die off slowly, naturally, so the dog's system doesn't have a bunch of worms dying off at once and clogging up the lungs, causing the dog to die. My vet said only the Heartgard brand will work for this and so far I am very pleased. That stray dog has now become part of our pack; we love him! He is the sweetest boy I've ever known. He is so incredibly loving and so very gentle - I just can't imagine anyone wanting to hurt him. He learns quickly and is eager to please. And, (sounding like a commercial), thanks to Heartgard, he has a much better chance at a long and happy life.
Date published: 2017-03-19
Rated 5 out of 5 by from Best Chewable Heartworm Protection! Ms. Miley is fussy, these are the only Heartworm Chewables she'll chew with no problem. So Mommy is very happy and Thank You 1-800-PETMEDS for selling these.
Date published: 2017-03-16
Rated 5 out of 5 by from they love them Very happy with the product and the prices are great the site is very easy to use and it works perfectly with your veterinarian
Date published: 2017-02-18
Rated 5 out of 5 by from HEARTGARD Annie loves the chewables, the taste and I don't need to use cheese or peanut butter.
Date published: 2016-11-18
Rated 5 out of 5 by from heart gard thanks pet meds, you all are a great company. my dog blackie thanks u and me.
Date published: 2016-08-23
Rated 5 out of 5 by from My dog won't usually eat any kind of chews for heartworm or behaviour, etc., but he gobbled this one right down. He used to be on the other multi heartworm-flea combo Trifexis, which was supposed to be a chewable but was hard and he would keep spitting it out. I had to grind it down to powder in a mortar & pestle and mix in with his food to get him to take it. The Heartgard he loves !!! Will continue to use this for the heartworm protection.
Date published: 2016-07-31
Rated 5 out of 5 by from 1800PETMEDS IS THE BEST! I am so happy with the fantastic customer service at 1800 PET MEDS, you have a loyal customer. I got my order much sooner than expected and am very grateful. I am really rating 1800PET MEDS not this product. Frankly I wish I didn't need to give this to my dog!
Date published: 2016-06-22
Rated 5 out of 5 by from Great for my pup! We have used heartgard since Wylie was born. He is doing great and loves the way Heartgard tastes!
Date published: 2016-03-08
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if my dog already has heartworms can I still give him the heartguard chewables

Asked by: Anonymous
Yes. It will kill the microfilaria (heartworm babies) so they don't turn into more adult heartworms. My dog had such a bad infestation, vets wouldn't treat and recommended surgical removal. That was five years ago, and my Little Rascal is still kicking, after only love and heartguard.
Answered by: Jonathan
Date published: 2017-02-20

Our dog tested positive several month ago. We have been giving her Heartgard plus . Will this medication cure the heartworm or is it only to prevent it? If it is not a cure do you have another medication or recommend what to do.

Asked by: GRamon
Heartgard is only used to prevent heartworms. Treating dogs with heartworm disease starts with a thorough physical examination by the veterinarian. The veterinarian will then discuss treatment options with you.
Answered by: Christine
Date published: 2016-10-13

What do I do if my dog is over 100 pounds

Asked by: Kdavis3663
If your dog is over 100 lbs, you would need to give him two pills; one from the brown box (51-100 lbs) and one from the corresponding box to equal the remaining weight. For example, the second pill would be from the blue box (1-25 lbs) if he weighs anywhere from 101-125 lbs. If he weighs 126-150 lbs, you would give him one pill from the brown box (51-100 lbs) and one pill from the green box (26-50 lbs).
Answered by: Christine
Date published: 2016-10-11

I was using trifexis and was only able to get my dog to take half of a pill. The other half disintegrated and I  have no more.  I want to switch to hartgard, which my vet ok'd but I  don't know when to give it to my dog

Asked by: KimP
Wait at least 2 weeks after giving Trifexis to start the new HeartGard medication.
Answered by: Christine
Date published: 2016-10-04

Is heart gard safe to use with nexgard?

Asked by: Goldens
Yes you can use these together.
Answered by: paulpharmacistintern
Date published: 2016-08-04

My dog is in between weight recommendations?

My dog is 25.4 lbs. Do I go with the up to 25 lb. size or 26-50 size. I'd rather not overmedicate if not necessary.
Asked by: Anonymous
I would check with your vet to find out his/her recommendation depending upon your dog's individual status. My vet would consider a dog's environment and risk of infection, age, and any other medical conditions in determining which strength Heartgard a dog should take when they are borderline.
Answered by: Anonymous
Date published: 2017-01-27

Will nexguard plus kill mosquito

Asked by: Anonymous
Nexguard is not labeled as killing mosquitoes. If you are thinking of using it instead of a heartworm prevention, even if it DID kill mosquitoes, the mosquito will still need to bite the dog, therefore is still able to transmit the heartworm larva. Heartworm preventions actually kill the larval stage of the heartworm after the mosquito has bitten.
Answered by: Anonymous
Date published: 2015-08-29

My dog's weight goes between 49-52 lbs, depending on the day. Which pack should I get him?

Asked by: Anonymous
The dose will ultimately be up to your veterinarian. It really depends on his current weight and how often he tends to go over 50 pounds. If he is borderline, at 50 pounds, some vets will go with the higher dose just to be on the safe side.
Answered by: Anonymous
Date published: 2015-07-14
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