Heartgard® (ivermectin) Chewable for Cats

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Product Details

Heartgard® Chewables for Cats

Product Information

Heartgard® is a chewable, beef-flavored tablet administered once a month to protect your cat from the threat of potentially deadly heartworm disease when given every month.

It is recommended that cats be tested for existing heartworm infections prior to starting treatment with Heartgard®.


Cats (at least 6 weeks of age)

Product Flavoring

Heartgard® is a natural beef flavored chewable.


  • Once a month beef flavored chewable treat that is highly palatable
  • When given at the recommended dose and regimen, Heartgard® is effective against the tissue larval stage of heartworm larvae for a month after infection resulting in the prevention of adult heartworms
  • Treats and controls hookworms (A. tubaeforme, A. braziliense) once monthly when given routinely
  • Approved for cats 6+ weeks of age, with no weight requirements

Active Ingredients



Heartgard® should be given orally as directed by your veterinarian. This medicaton should be administered at monthly (every 30 day) interals, year-round to guarantee protection from heartworms.  For cats over 15 lbs, use the appropriate comination of chewables to ensure complete protection agains heartworms.

Remove only 1 chewable at a time from the foil-backed blister card and return the card to the box to protect from light. Do not remove chewable from foil wrapper until you are ready to give it to your cat. Offer to the cat as a treat by hand or in a small amount of cat food. Heartgard® should be chewed and not swallowed whole. For pets that consume treats whole without chewing it is advised to break up chewable and give in small pieces. Make sure entire tablet is consumed. Do not use if chewable is too hard to chew or break apart.

Missed Doses

Give the dose as soon as you remember, unless it is time for the next dose. Do not double dose.  If your cat has missed a dose please consult with your veterinarian as testing may be recommended sooner than usual.

Side Effects

Heartgard® is generally well tolerated in cats. There are very few side effects when the drug is given at the usual dose. The following side effects have been reported with the use of Heartgard®: depression, lethargy, vomiting, anorexia, diarrhea, mydriasis, ataxia, staggering, convulsions, and hypersalivation.  

Other side effects may occur. If you notice anything unusual, contact your veterinarian.

Drug & Food Interactions

There are no known drug interactions with ivermectin. Contact your veterinarian if your pet experiences any unusual reactions when different medications are given together. Make sure to tell your veterinarian what other medication you are giving to your pet. Quite often your veterinarian may prescribe two different medications, and a drug interaction may be anticipated. In this case, your veterinarian may vary the dose and/or monitor your pet more closely.


Heartworm testing should be performed prior to the start of prevention therapy. If the animal is off Heartgard® 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.

Allergic reactions to medications may occur. Be sure to inform VetSource and your veterinarian if your pet has any known drug sensitivities or allergies. If your pet displays symptoms of an allergic reaction, call your veterinarian immediately or go to a veterinary emergency clinic. Symptoms may include but are not limited to: swollen lips, tongue, face, airways; difficulty breathing; agitation; profuse salivation; vomiting; widespread hives and itching.

Adverse Reaction

If you are concerned that your pet has experienced an adverse reaction to this medication or you have concerns about the product, please contact the manufacturer, Merial, at 888-637-4251 or contact Vetsource customer service at 877-738-4443.


Store long term at 68-77 degrees F. Excursion between 59-86 degrees F are permitted. Store in original packaging to protect from light.  Keep out of reach of children and pets.