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Heargard for Dogs - Heartworm Treatment Guide

How Ivermectin Prevents Heartworms in Dogs

By Team PetCareRx. May 22, 2013

Heartgard Box - Chewable

indications for Heartgard for Dogs

Ivermectin, the active ingredient in Heartgard for dogs, is used to prevent heartworms in dogs. Ivermectin attacks the central nervous system of juvenile heartworms, killing them, and preventing any serious affects of heartworms for your dog. The low doses of Ivermectin in heartworm prevention medications cannot treat heartworms once your dog already has them, but they are completely effective in prevention.


Certain dogs cannot handle Ivermectin and can experience Ivermectin toxicity. While the doses of Ivermectin are extremely low in preventative heartworm medications like Heartgard, certain breeds are predisposed to Ivermectin toxicity and should be under strict veterinary supervision if they do take Heartgard. Susceptible breeds include: Collie, Australian Shepherd, Shetland Sheepdog, English Sheepdog, Old English Sheepdog, German Shepherd, Longhaired Whippet, Silken Windhound, and Skye Terrier.


Heartgard for Dogs comes in chewable tablets. There are a number of dosage sizes; your vet can determine an appropriate size based upon your dog's weight. One chewable tablet is administered once a month.

Side Effects

Most dogs do not experience negative side effects from the low levels of Ivermectin in Heartgard; with higher doses of Ivermectin, however, the symptoms become more likely. Possible negative side effects include: vomiting, dilated pupils, muscle tremors, blindness, uncoordination, lethargy, lack of appetite, and dehydration.

Brand/Generic equivalents

Generic name of Heartgard for Dogs : Ivermectin

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Heartgard for Dogs at a glance

  • 1For dogs
  • 2A heartworm preventative
  • 3An oral medication
  • 4Treats intestinal worms and prevents heartworm
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